# Dado cutters - Please, what is so dangerous about them



## Sawdust (21 Jun 2006)

Hi,

I am trying to find out why it is that so many people on here are against dado cutters. I’ve searched the forum and have found loads of topics talking about them and while most people seem to agree they are the spawn of the devil, no-one actually gives any reasons why. I am seriously thinking about buying one but would like to know what the real dangers are and how the compare to other potentially dangerous machines.

If I do buy one, it would initially be for use on a radial arm saw, but if and when I acquire a table saw, I would also like to use the dado on it.

I appreciate that on most saws they have to be used without a guard in place but is that the main reason for people not liking them and if so, surely it’s possible to devise some sort of guard for them. I can also see that a riving knife is not practical with them but given that in most cases they will be making very shallow cuts and I presume would never be used to cut all the way through the stock, is there much of a risk of kickback?

I also understand that the HSE don’t like them, but then they also told me I can’t use Tipex or a craft knife at work and haven’t they banned ladders? I also can’t understand why they are not considered so dangerous in the States, surely our American friends are every bit as keen to remain attached to their fingers as we are?

So am I missing something; do they explode unexpectedly, come undone and fly across the workshop, give off radiation or maybe fire bullets at the operator?

Finally, how do people think they compare with other dangerous activities, for example using a spindle moulder, a chainsaw, a 9inch angle grinder or driving on the M1?

I am not trying to sound flippant, and if I am missing something vital then I would be grateful for finding out but to me they don’t look any more dangerous if used carefully than quite a few other machines which don’t seem to attract the same criticism.

I would really appreciate people’s thoughts on this, particularly people who use them and are still alive and also from anyone with any bad experiences (assuming they can still type!)

Thanks
Mike


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## prawnking (21 Jun 2006)

one thing i do know is you r not supposed to use a dado cutter on a table saw that has a brake to slow the blade down when it sturned off. i belive this is a feature of more modern table saws and thats 1 of the reasons why u cant use them, also because of the gaurd thing. but i maybe wrong feel free to correct me.

cheers

shaun


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## Sawdust (21 Jun 2006)

prawnking":w7zr4uwp said:


> one thing i do know is you r not supposed to use a dado cutter on a table saw that has a brake to slow the blade down when it sturned off. i belive this is a feature of more modern table saws and thats 1 of the reasons why u cant use them, also because of the gaurd thing. but i maybe wrong feel free to correct me.
> 
> cheers
> 
> shaun



Thanks Shaun,

That is a good point, I understand that it could be possible for them to come undone while the saw is braking, but I suspect that the same applies to a large 'standard' blade with the same momentum. My RAS is old and unbraked, so it wouldn't be a problem there, but I wonder if there is some kind of locking mechanism on modern braked table saws to prevent blades coming undone?

Cheers
Mike


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## SketchUp Guru (21 Jun 2006)

Mike, I've used a dado set many times. Never had any problems. No kickback, no worries about a lack of blade guard (the blade is buried anyway so it's _almost_ like having the guard in place.

In the US, a dado set with a tablesaw is almost as common as windshield wipers on a car. If you've got one, you've got the other.

A dado set does have more inertia that a single blade and depending on how the arbor nut is locked, I could see the validity of worries about it coming loose during breaking. I don't know about breaking on tablesaws--we aren't that sophisticated here--but on other tools that have the breaking action, they essentially try to reverse the motor while it is spinning. The circuit cuts out at some lower RPM. There might be some concern about the electronics because it would take longer to slow the motor to the "cut out" RPM. I suppose that could let the magic smoke out.


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## Sawdust (21 Jun 2006)

Dave R":rjc7g9wn said:


> Mike, I've used a dado set many times. Never had any problems. No kickback, no worries about a lack of blade guard (the blade is buried anyway so it's _almost_ like having the guard in place.
> 
> In the US, a dado set with a tablesaw is almost as common as windshield wipers on a car. If you've got one, you've got the other.
> 
> A dado set does have more inertia that a single blade and depending on how the arbor nut is locked, I could see the validity of worries about it coming loose during breaking. I don't know about breaking on tablesaws--we aren't that sophisticated here--but on other tools that have the breaking action, they essentially try to reverse the motor while it is spinning. The circuit cuts out at some lower RPM. There might be some concern about the electronics because it would take longer to slow the motor to the "cut out" RPM. I suppose that could let the magic smoke out.



Thanks Dave,

The only concerns expressed so far are to do with braked motors - not a problem on my RAS as it's old and possibly a good reason for finding a nice old table saw without a brake!

Cheers
Mike


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## engineer one (21 Jun 2006)

mike,
i do not think people here as users have a down against dado cutters,
it is purely an HSE thing. the manufacturers here cannot sell a 
saw without the guard and riving knife. should they seel the
accessories, then they would be liable for any accidents due
to bad fitting of the product.

it used to be possible to buy cutters for cabinet hinges, i.e. 35 mm
ones to use in the drill press. now however the same product without
any changes has to be sold for use in a router. HSE again.

because of space limitations, we in england tend to make more use
of router tables, and cut dado's there, or freehand with a guide.

finally i think the major complaint from hse is that people tend not 
to remove the blade from there saw whilst not in use, and in a 
production shop mistakes could be made.

paul :wink:


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## Alf (21 Jun 2006)

Scrit summed up the important bits pretty well here. 

Cheers, Alf


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## Sawdust (21 Jun 2006)

Alf":1ivtkk72 said:


> Scrit summed up the important bits pretty well here.
> 
> Cheers, Alf



Alf,

I've read the post by Scrit that you pointed me at and it seems the salient points are:

They are OK on a RAS - that's great as I have one! We will ignore for the moment the fact that I removed the lower blade guard from it because it was a pain in the bum and just got in the way. (my personal feeling only of course - not a recomendation to others)

Manufacturers are scared of supplying them in case they get sued. Well that applies to everything now, I'm sure lawn mowers will be banned soon.

Same comments as others have made about braking, although I fail to see why, if a wheels can stay on a car under heavy braking (eg emergency stop with the wheels locked up), manufacturers can't make a blade stay on a saw where the braking is pathetic anyway. 

They are dangerous on table saws because they are difficult to guard. I suppose this opens up another question; are they difficult or impossible? I can see that guards attached to the splitter won't work but a lot of those, especially on cheap saws are rubbish and I wouldn't trust one to protect me from anything. How about one of the overarm guards, or something attached to the fence?

Cheers
Mike


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## wrightclan (21 Jun 2006)

:-$ [-( :-# 

Brad


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## Sawdust (21 Jun 2006)

wrightclan":car60i2n said:


> :-$ [-( :-#
> 
> Brad



eh?


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## wrightclan (21 Jun 2006)

Those emoticons mean 'shh,' 'I'm not talking,' and 'silenced.' Last time, I brought up a common American woodworking practice, that is little used here, I got beat down pretty heavily. So:

:-$ [-( :-# 

Brad


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## Sawdust (21 Jun 2006)

wrightclan":2e97v460 said:


> Those emoticons mean 'shh,' 'I'm not talking,' and 'silenced.' Last time, I brought up a common American woodworking practice, that is little used here, I got beat down pretty heavily. So:
> 
> :-$ [-( :-#
> 
> Brad



Thanks for the explanation Brad, I've never really managed to understand the emoticons!

I was expecting to get a hammering over the question as well, it does seem to attract a lot of replies although most of the ones I've seen in the past are along the lines of "dados are bad because they are". 

Cheers
Mike


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## Adam (21 Jun 2006)

Sawdust":33jvtobd said:


> Hi, I am trying to find out why it is that so many people on here are against dado cutters.



I don't think people are against them as such. Its just they are so easily done with a router and a guide. I for one, take the crownguard off my Scheppach table saw but at least the riving knife stays in place. Each person has their own limits I guess. As to braking, remember saws have a single nut on a central spindle, not at all like the multipoint bolts used to secure a car wheel. Additionally, tablesaws run at pretty significant RPM. A dado is heavier, to if it does catch its got more momentum to launch something towards you.

I think spindle moulders also have a reputation (perhaps unfairly - see Scrits post recently) as being dangerous, so its not just the dad thats being singled out.

Adam


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## johnelliott (21 Jun 2006)

I think it is one of those situations where if people can't see for themselves what is wrong with having a unguarded dado blade in a tablesaw then there is no way that anyone else (even Scrit) is going to be able to explain it to them. That is why there have to be laws about this kind of thing.
Similar situation to when the helmet law for motor cyclists was passed. All kinds of protests, most of which were along the lines of "I've been riding motor bikes for twenty years and never needed a helmet"

All the above IMHO, of course

John


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## Jake (21 Jun 2006)

It seems safe to say that someone who removes the guard from a RAS is unlikely to be convinced that other safety precautions are worthwhile or of much importance. Given that, this thread is pointless.

This debate has been done to death and the danger or lack of real danger has been discussed at length. No-one is likely to swap sides, so why bother talking about it?


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## Sawdust (21 Jun 2006)

Jake":144inoye said:


> It seems safe to say that someone who removes the guard from a RAS is unlikely to be convinced that other safety precautions are worthwhile or of much importance. Given that, this thread is pointless.



Pointless eh?

Please read my post before misquoting me!

I have asked the question in order to find out WHY the dado is considered so dangerous, I was hoping the experts here would be able to help.

I did not remove the whole guard; that would dangerous as well as pointless. I removed the lower part of it because, in my opinion, it made the saw more dangerous to use. Granted it may be a badly designed guard. I consider safety to be of utmost importance and after careful consideration I removed the lower part of the guard because I felt safer using the saw when I could see the blade.

If you read some of my other points, one of the things I am asking is how can a dado be guarded. If I was not concerned about safety, I would not of started the original post would I?

Cheers
Mike


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## Jake (21 Jun 2006)

Yes, it is pointless - as has been proven in a million threads before this one. It has all been discussed before, including guarding, as you'll have seen from the archive if you've read it all.


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## Sawdust (21 Jun 2006)

Adam":1e9nefpj said:


> Sawdust":1e9nefpj said:
> 
> 
> > Hi, I am trying to find out why it is that so many people on here are against dado cutters.
> ...



Fair point, although car wheels turn pretty fast too and are a lot heavier than a dado cutter!



Adam":1e9nefpj said:


> A dado is heavier, to if it does catch its got more momentum to launch something towards you.


Also a good point, although I still feel a dado cutting a shallow groove part way through a board is less likely to bind in the cut than a standard blade cutting right through. I'm happy to be corrected though.



Adam":1e9nefpj said:


> I think spindle moulders also have a reputation (perhaps unfairly - see Scrits post recently) as being dangerous, so its not just the dad thats being singled out.
> 
> Adam


We all have our own danger thresholds and I wouldn't go near a spindle moulder !!

Cheers
Mike


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## Sawdust (21 Jun 2006)

Jake":khlt3s5b said:


> Yes, it is pointless - as has been proven in a million threads before this one. It has all been discussed before, including guarding, as you'll have seen from the archive if you've read it all.



What has been proven?

As I also stated at the start, I did search and read the threads and didn't find the answer to my question so I asked it. I stand by my comments that most answers are along the llines of they are dangerous because they are!

All I wanted to know was why.

Cheers
Mike

Modedit Newbie_Neil


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## johnelliott (21 Jun 2006)

johnelliott":11gqz2ji said:


> I think it is one of those situations where if people can't see for themselves what is wrong with having a unguarded dado blade in a tablesaw then there is no way that anyone else (even Scrit) is going to be able to explain it to them. That is why there have to be laws about this kind of thing.
> Similar situation to when the helmet law for motor cyclists was passed. All kinds of protests, most of which were along the lines of "I've been riding motor bikes for twenty years and never needed a helmet"
> 
> All the above IMHO, of course
> ...


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## Jake (21 Jun 2006)

Sawdust":1q87h2cq said:


> What has been proven?



The pointlessness of discussing the safety of dados



> As I also stated at the start, I did search and read the threads and didn't find the answer to my question so I asked it. ... Your replies have not helped in any way, unlike others that have at least provided valuable information.



As no-one has said anything that hasn't been said before, my replies, however pointless, have added as much to sum of knowledge as anyone else's.

Cheers - this isn't personal. It just all gets a bit tedious after the tenth time it flares up yet again and round and round we go. I'll step away and ignore the thread!

Jake


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## Newbie_Neil (21 Jun 2006)

Gentlemen

If there is any more personal abuse posted this thread will be locked down.

PLEASE don't make me do that.

Thanks
Neil


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## Jake (21 Jun 2006)

There hasn't been any personal abuse.


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## Sawdust (21 Jun 2006)

johnelliott":1knswn0c said:


> I think it is one of those situations where if people can't see for themselves what is wrong with having a unguarded dado blade in a tablesaw then there is no way that anyone else (even Scrit) is going to be able to explain it to them. That is why there have to be laws about this kind of thing.
> Similar situation to when the helmet law for motor cyclists was passed. All kinds of protests, most of which were along the lines of "I've been riding motor bikes for twenty years and never needed a helmet"
> 
> All the above IMHO, of course
> ...



I did ask at the beginning, that if the major concern was the lack of guarding then was there a satisfactory way of guarding the cutter. I was also asking if there was anything else I had failed to think of that added an unexpected danger to the operation.

suppose I attached a steel plate to the fence that completely covered the blade and prevented my hands from getting anywhere near the cutter, would you then consider the operation to be safe?

Mike


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## Sawdust (21 Jun 2006)

Jake":1ei81vc6 said:


> There hasn't been any personal abuse.



Thanks Jake,


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## engineer one (21 Jun 2006)

jake
sorry have to agree with neil it appears to be personal.  

the big problem with any forum is that questions will come around 
again as people join, or forget how to get the old links.

when so many people now watch norm ( :lol: )
and see the dado head in use on a table saw it is bound to 
raise questions.

safety is also a thing which will always be contentious, not least
because so many hse decisions these days appear to be restrictive
on the qualified, but as scrit has said before few get the proper 
qualifications these days so better to find a way round than to lose
bits of your body because you did not think things through.

mike as i said at the beginning, with dadoes being banned over 50 years
ago in the uk, many myths have arisen, kind of like the constant
suggestion from many "qualified" people over here i meet who tell
me on a regular basis that mdf is banned in the usa.
as anyone reading american woodworker, pop wood, or fww will know
this is untrue, but the myth has grown up.

guards on almost all machines could be improved dramatically 
by building your own. and for instance the so called cross cut sled 
favourite in many american programmes and magazines
offers great opportunities for making safer guarding.

personally i think you are wrong about the dado blade catching and
slinging back the panels, because it is only cutting half the 
wood for instance, but since in many cases people cut dadoes
in panel goods, there are better chances of catching due to what is 
in the panel goods. the other thing to think about is without some form
of downward pressure, the dado will vary in depth as
you move a long board over the blades.

this will of course not be true with an RAS.

i know it is hot, and our football team did not play well last
night, but lets at least cool this off a bit :lol: 

paul :wink:


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## StevieB (21 Jun 2006)

Its a fair question, and one which comes up alot. It receives different answers depending on which side of the debate you are on. My understanding is as follows:

Dados are not banned in the UK, if you have a saw that is designed to take one then they are perfectly fine. However, such a saw is usually imported. David Free covered this topic quite well when the Great British Woodshop was first aired. The HSE legislates for business, not the home user / hobbyist. Whether the above is true in an industrial setting I wouldn't know, but the HSE website is a mine of information - some of it may even be relevant!

The original question is why are they more dangerous. Simply put, they are unable to take standard guarding, requiring a fence mounted guard or overhead guard. These are not as protective as a crown guard and do not have a riving knife. They also have a greater mass, more inertia and therefore do more damage if the worst should happen. Finally, a Dado is only one way of doing something. There are other, safer ways. Risk assessment suggests that the most safe option should be used to accomplish a task. 

My understanding is that if your RAS is designed to accommodate a Dado, and you are not in an industrial setting, you are free to do so. That is my understanding rather than carte blanche to go ahead though!

Steve.


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## Sawdust (21 Jun 2006)

engineer one":2tzxh7kq said:


> jake
> sorry have to agree with neil it appears to be personal.



Actually Neill chopped my message to Jake because I was a little offended that he misquoted me!

I genuinely didn't think I was being offensive but if others did, then I apologise.



engineer one":2tzxh7kq said:


> i know it is hot, and our football team did not play well last night, but lets at least cool this off a bit



I was in the workshop last night, keeping as far away from the telly as possible !!



Cheers
Mike


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## Newbie_Neil (21 Jun 2006)

Sawdust":1mnlb7rs said:


> Jake":1mnlb7rs said:
> 
> 
> > There hasn't been any personal abuse.
> ...



Personal abuse _*has*_ been posted posted in this thread, I have removed it.

Neil


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## Jake (21 Jun 2006)

I saw it, and I wasn't offended.

I didn't misquote you - I didn't quote you at all - but I should have said "part of" before guard. My point stands, though. It wasn't meant as an insult, though, it is just an observation about people's personal perceptions of risk.

Anyway, I'm out of here.


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## Anonymous (21 Jun 2006)

You must enter a message when posting


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## Sawdust (21 Jun 2006)

Mr_Grimsdale":1f8ul65f said:


> I use a wobble saw for slots, which is a variety of dado cutter. It's fast, clean-cutting, accurate, easily adjustable between 6 and 22 mm, dust free (compared to router), safe: it can't bind or snatch as it is cutting in a slot wider than itself. In one tool replaces dozens of router cutters and does a much better job at fraction of cost.
> Weight not an issue - it's no heavier than a typical saw blade. The only safety issue is the fact that the large widely spaced teeth become invisible at speed. Could be a prob in shared workshops if careless people left machine un-attended and still on - but that applies to most machines.
> I mentioned this on another group a year or so ago and it attracted mass hostility and horror - but entirely from people who had clearly never used one and probably never seen one.
> Was £50 (no brand name) from local saw doctor. Highly recommended!
> ...



I didn't know they were still available although I did see one in use a long time ago. It did cut very cleanly and I was told at the time it puts less strain on the motor than a dado cutter although I doubt this is an issue an anything other than the lightest of saws.

It did scare me because the edge of the blade was hard to see and rightly or wrongly, I like to see the blade cutting and exactly where it is going.

There was also some debate as to whether the bottom of the cut was flat or slightly curved. I thought it was flat but others disagreed.

I suppose if well guarded, it's pretty much the same as the dado cutter.

Thanks
Mike


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## Mike.C (21 Jun 2006)

> Jake,
> 
> It seems safe to say that someone who removes the guard from a RAS is unlikely to be convinced that other safety precautions are worthwhile or of much importance. Given that, this thread is pointless.
> 
> This debate has been done to death and the danger or lack of real danger has been discussed at length. No-one is likely to swap sides, so why bother talking about it?



Jake, no offence, but how can a thread about safety be pointless? Sawdust wants/wanted to know why we thought dado's were dangerous. Yes you may have discussed this topic before, but after reading past threads he obviously wanted to see if anyone could add something more.

Jake, do not forget that there are sure to be many hundreds of non members, who may have just come across Ukworkshop, and who may be new to woodworking and have no idea that dado's can be dangerous. In a case such as this, Sawdust's thread is far from pointless.

Would i be right in saying that although HSE have not banned dado head cutters, they have told manufacturers that to come inline with British Standards, they can only fit a small arbor to their saws, and that because of this a dado cannot be fitted to them.

Cheers

Mike


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## johnelliott (21 Jun 2006)

Sawdust":33pmh3nf said:


> johnelliott":33pmh3nf said:
> 
> 
> > I think it is one of those situations where if people can't see for themselves what is wrong with having a unguarded dado blade in a tablesaw then there is no way that anyone else (even Scrit) is going to be able to explain it to them. That is why there have to be laws about this kind of thing.
> ...



This is from Scrit's advice in the thread that Alf referred us to earlier
"Those who say they (dado heads) are safe without any training or length experience are living in a bit of a fools paradise - they've yet to encounter a knot, shake or crack in the middle of a cut. That's when it gets "interesting" as a dado head can smash a piece of timber pretty easily and having a piece of 1in oak literally explode as the dado head finds that thunder shake is the sort of experience which can ruin your composure (and your underwear, too)! -- Been there, done that and ruined the underwear into the bargain!!!!! "

John


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## Kane (21 Jun 2006)

What would happen if you hit such a defect with a router?


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## engineer one (21 Jun 2006)

the router would fly, more likely than the wood.

by its very design, you tend to stand behind the wood when using a 
table saw, on a router table or freehand you stand to one side
thus reducing the personal, but not the workshop risk.

paul :wink:


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## Sawdust (21 Jun 2006)

johnelliott":9gse6avs said:


> Sawdust":9gse6avs said:
> 
> 
> > johnelliott":9gse6avs said:
> ...



This does indeed sound scary and I would not want to be around when it happened.

However, would a big router cutter be any better in similar circumstances, or what if a planer hits the same shake or knot.

Mike


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## Adam (21 Jun 2006)

Sawdust":8qemfj8q said:


> However, would a big router cutter be any better in similar circumstances, or what if a planer hits the same shake or knot.
> Mike



Yes, it would be much better surely. A) The mass of the cutter is much less B) the rotational speed of the cutter is much less, especially if its a physically larger cutter C) the user is normally holding the router with two hands D) if its on a router table, then more than likely then holddowns are being used. (or are at least available). With only the depth of the router bit itself in the wood, once that is lifted (forced) ripped, or however it exits, it is doesn;t continue to exert any force on the router, and hence its safer. The user normally has access to the power switch, possibly quicker than getting a hand on the off button. The router cannot "pickup" and smash the wood into the user. Just a few reasons - not neccasarily all true, but all possibilities at least.

Adam

On a planer, the the infeed and outfeed tables are set to a different height, the wood cannot be dragged into the cutter as the tables prevent this, and the balde cannot normally be signficiantly exposed - so its only taking light cuts


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## Anonymous (21 Jun 2006)

You must enter a message when posting


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## dedee (21 Jun 2006)

From the Axminster Product Decsription 
*N.B. These wobble saws are intended for use on spindle moulders only. *

Andy


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## Sawdust (21 Jun 2006)

engineer one":2cz200df said:


> the router would fly, more likely than the wood.
> 
> by its very design, you tend to stand behind the wood when using a
> table saw, on a router table or freehand you stand to one side
> ...



Flying oak is dangerous, but a flying router, now that would be fun


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## Kane (21 Jun 2006)

I think I'll switch to hand tools!!!


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## Adam (21 Jun 2006)

Sawdust":kc7akorr said:


> Flying oak is dangerous, but a flying router, now that would be fun



I do not believe the momentum in a router bit, transfered to the weight of a router, could propel it to any degree. This is due to the (relatively) low weight, and close proximity of the cutting surfaces to the centre of the spin of the spindle, compared to the reasonably heavy weight of a router. The router bits are normally only weighing in the order of grams, they simply do not contain much energy. Even adding in the spinning weight of the motor of the router, they are still small and lightweight - they are designed to be "portable". The momentum of a dado is much greater, and the cutting edge acts at a much greater distance. The weight of wood is not to be ignored, and when launched at speed at you, will cause injury. Additionally, table saws have much much higher power motors, and the momentum in those, the spindle etc is much more significant, as they have to cope with deep rip cuts. Perhaps thats the best reason I can think of.... the amount of stored energy in a router at cutting speed compared to a tablesaw at cutting speed.

Adam


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## Sawdust (21 Jun 2006)

Adam":857ww0b0 said:


> Sawdust":857ww0b0 said:
> 
> 
> > However, would a big router cutter be any better in similar circumstances, or what if a planer hits the same shake or knot.
> ...



Adam,

To take things to extremes, compare a raised panel cutter in a router table to a dado cutter in a table saw taking a very thin and shallow cut, extreme yes, but which is the most scary/dangerous? Also a router on its slow setting is faster than a table saw.

As for a planer, according to the specs, mine can take a 3mm cut off a 10 inch wide board (sorry for mixing my units), that's a lot of wood and my opinion, the guard is not great (and no I haven't removed it). If that hit the same knot there would be wood everywhere. This hasn't happened to me but has to a friend and it had a similar effect on him to the one Scrit describes with the dado.

Mike


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## wrightclan (21 Jun 2006)

Adam":2v436ro6 said:


> Yes, it would be much better surely. A) The mass of the cutter is much less B) the rotational speed of the cutter is much less, especially if its a physically larger cutter C) the user is normally holding the router with two hands D) if its on a router table, then more than likely then holddowns are being used. (or are at least available). With only the depth of the router bit itself in the wood, once that is lifted (forced) ripped, or however it exits, it is doesn;t continue to exert any force on the router, and hence its safer. The user normally has access to the power switch, possibly quicker than getting a hand on the off button. The router cannot "pickup" and smash the wood into the user. Just a few reasons - not neccasarily all true, but all possibilities at least.
> 
> Adam
> 
> On a planer, the the infeed and outfeed tables are set to a different height, the wood cannot be dragged into the cutter as the tables prevent this, and the balde cannot normally be signficiantly exposed - so its only taking light cuts



I'm sorry, but I have to break my self-imposed silence on the issue. The rotational speed of a router is much higher than a sawblade. Most tablesaws go no higher than 4,000rpm. Most routers go no lower than 8,000 rpm. If you use appropriate pushers and hold-downs with the dado, it will not '"pickup" and smash the wood into the user.' Remember, as well, that in a dado blade most of the 'mass' that everyone is concerned about is in the form of two tooth chippers. The fewer the teeth (and the shallower the cut), the less resistance. That's why you don't use an 80 tooth blade for ripping. I *have* had some gnarly bits thrown at me from a router in a table. *Understanding how wood works and how forces of machinery work in relation to the wood, will keep you far safer than all the guards in the world.*

By the way, I do use a dado cutter, but not really that much--I just don't do a lot of work where it would be an advantage. Now and then, it is an advantage, and I use it.

Brad


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## Anonymous (21 Jun 2006)

You must enter a message when posting


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## Sawdust (21 Jun 2006)

wrightclan":24uj4eoq said:


> Adam":24uj4eoq said:
> 
> 
> > Yes, it would be much better surely. A) The mass of the cutter is much less B) the rotational speed of the cutter is much less, especially if its a physically larger cutter C) the user is normally holding the router with two hands D) if its on a router table, then more than likely then holddowns are being used. (or are at least available). With only the depth of the router bit itself in the wood, once that is lifted (forced) ripped, or however it exits, it is doesn;t continue to exert any force on the router, and hence its safer. The user normally has access to the power switch, possibly quicker than getting a hand on the off button. The router cannot "pickup" and smash the wood into the user. Just a few reasons - not neccasarily all true, but all possibilities at least.
> ...



Brad,

There's probably an emoticon for loud applause but I don't know it so I'll just say thanks.

Cheers
Mike


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## Adam (21 Jun 2006)

wrightclan":wiq9iac6 said:


> Most tablesaws go no higher than 4,000rpm. Most routers go no lower than 8,000 rpm.



OK, but rotation speed of the spindle has no relation to the speed of at the cutting tips. Thats a function of RPM but the RPM itself is no guide.

For example. Assuming a 250mm diameter table saw blade, that is operating at 4000 rpm as you indicate. That means its speed is 

66 revolutions per second, at (pi x 250mm) = 0.78meters per turn, 

So the speed of the dado blade is 51 meters per second with lots of momentum.

Lets assume a 1inch dado, and you are using a 1 inch diameter cutter (large I know). therefore, lets use 8000rpm

25 millimeters x pi = 0.0785398163 meters = 10meters per second with much less momentum.

So, as I said, the router goes a lot slower, with a lot less momentum.

Adam

If you use a more realistic 12mm cutter on the router, and wind it up to 12000rpm it drops to 7.53meters per second.


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## wrightclan (21 Jun 2006)

Adam":2yxhlzyn said:


> wrightclan":2yxhlzyn said:
> 
> 
> > Most tablesaws go no higher than 4,000rpm. Most routers go no lower than 8,000 rpm.
> ...



My router goes up to 32,000 rpm. You also won't find a 10 inch (250mm) dado blade anywhere--they're usually either 6inch or 8 inch. My tablesaw turns at 2800rpm that's 29.8 metres per second. A 1/2 inch bit at 32,000 (which is not unreasonable) travels at 20.9 metres per second--not that far off now. But they are turning in different planes, so the forces are different. 

But that still does not address the issue that each of the teeth of a dado cutter are taking relatively small individual cuts, with relatively little resistance. And further, it does not address my ultimate point: *Understanding how wood works and how forces of machinery work in relation to the wood, will keep you far safer than all the guards in the world. * Perhaps I should qualify this by saying it will keep you safer than just using guards without the aforementioned understanding.

Brad


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## johnelliott (21 Jun 2006)

Mr_Grimsdale":136h9ill said:


> Visiblity not an issue when in use as the blade is out of sight under the workpiece - which also makes it very safe.



There is the 'small' matter of when the blade is exposed at the start and end of the cut.

John


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## johnelliott (21 Jun 2006)

wrightclan":2lmqiaet said:


> ,
> 
> *Understanding how wood works and how forces of machinery work in relation to the wood, will keep you far safer than all the guards in the world. * Perhaps I should qualify this by saying it will keep you safer than just using guards without the aforementioned understanding.



Understanding that people sometimes slip, especially on sawdusty floors, and that sometimes people feel a little dizzy, without warning, or that they can be distracted, or that sometimes bad stuff happens, and* that therefore one should keep guards in place* will keep you much safer _than knowing how wood works and the how the forces of machinery work in relation to wood._
John


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## wrightclan (21 Jun 2006)

johnelliott":zur9chbw said:


> wrightclan":zur9chbw said:
> 
> 
> > ,
> ...



Did I ever advocate removing guards? OK, you need to remove factory-fitted guards to use a dado, but I did mention using appropriate pushers (not those silly plastic things that come with tablesaws) and hold-downs--these are in effect guards. As far as your **** happens, etc., this is an issue for knowing your limits and using a safe stance, etc., not relevant to whether dado's can be used safely.

Brad


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## Noel (21 Jun 2006)

Overhead guard works well.


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## matthew (21 Jun 2006)

I'm probably missing something 'cos I'm still relatively new to this, but I don't really see the attraction of a dado set?

Perhaps for those in production environments - but they don't have the option anyway, what with H& S regs.

For the amateurs among us, are you really cutting that many dados to make it worthwhile? The expense of the set, the time spent changing the blades? Can't it be done just as easily with a router and clamp guide, or by making multiple passes with the normal table saw blade?

Matthew


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## johnelliott (21 Jun 2006)

wrightclan":23qc0jon said:


> As far as your **** happens, etc., this is an issue for knowing your limits and using a safe stance, etc., not relevant to whether dado's can be used safely.



Well, there we will have to agree to disagree. 

I would be interested to know what the others who are reading this think about this, though. Do they think that _knowing their own limits _is going to save them in a **** happens scenario? 
I thought that **** happening was something that, in itself, couldn't be prevented. I thought that was what **** happening meant. 
The point I was trying to make was that one should strive to lessen the impact of the **** by chosing to avoid unsafe working methods.

John


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## JPEC (21 Jun 2006)

Refering to questions posed on Norm's site, the only reason dado cutters do not conform to European standards is that they take longer to come to a stop after the saw is switched off, than is permissable.

Julian


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## Sawdust (21 Jun 2006)

All,

This has been an interesting debate and I thank everyone who has contributed and I'm sorry if I've raked over old ground or touched a few nerves. I feel I know a lot more about dado safety than I did this morning and it seems to me that the major concerns are:

The saw's braking mechanism allowing the blade to come off, this would definitely put me off using one on a braked saw.

The inability to use the saw's standard guards, but I think this could be overcome with suitable overhead guarding.

It's not possible to use a riving knife. As far as I can see, there is no way round this and I'm unsure how much of a risk this is.

It appears that a RAS is much more suitable than a table saw for using a dado cutter and I'm still very tempted to get one and use it on the RAS and once I feel comfortable with how it cuts I will probably use it on a table saw with a good overhead guard and hold down.

Thanks again for all the advice and comments.

Mike


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## Anonymous (21 Jun 2006)

You must enter a message when posting


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## wrightclan (21 Jun 2006)

Mr_Grimsdale":2idot3f8 said:


> johnelliott":2idot3f8 said:
> 
> 
> > Mr_Grimsdale":2idot3f8 said:
> ...



You can solve the visibility issues by making a zero clearance insert for your saw, and get cleaner cuts, as well. If you think you need a riving knife, you can make your own wooden one that fits into the insert.

Brad


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## wrightclan (21 Jun 2006)

johnelliott":32z41sdm said:


> wrightclan":32z41sdm said:
> 
> 
> > As far as your **** happens, etc., this is an issue for knowing your limits and using a safe stance, etc., not relevant to whether dado's can be used safely.
> ...



No offense, but maybe you shouldn't drive a car, or even leave your own house. Or use powertools at all, if you want to keep yourself from all conceivable risks. 

I thought I just described how to 'avoid unsafe working methods' when using dado cutters.


Brad


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## SketchUp Guru (21 Jun 2006)

It is interesting to me that if Brad's post were made on a US woodworkers forum, the conversation would be related to which brand of dado set to buy and whether one should buy a 6" or an 8". There might be a little discussion about wobble blades but the majority of responses would be suggesting stacked sets.

I would love to see real riving knives on the common saws here in the US as you have there. they make much more sense than the splitters we have here. I wouldn't like to give up the longer arbor that I have now, though.

The only injury I've ever received from a tablesaw is while I was cleaning the anti rust gunk out of one of the mitre guarge slots. Two little slits in a fingertip covered with mineral spirits will get your attention. the thing wasn't plugged in nor was there even a blade installed. 

I use a dado set when that method of cutting dadoes or rabbets makes sense. I also make coves with the tablesaw which I guess would also get you killed in the UK. (he ducks. )

I'll use a router for daoes, too. It all depends upon which tool makes more sense in the specific application at the time and depending on which machine I want to set up. Sometimes I have the router table set up for something else. Sometimes its the tablesaw. Sometimes I use the router on the Rat. Sometimes the Legacy.

I've suffered more injuries from handsaws and chisels than all my power tools combined. Actually, the only power tool induced injury beside the aforementioned was pulling a muscle in my back lifting the planer (thicknesser) onto the stand. Oh and Scrit, cover your eyes.  I have never had a guard on my tablesaw blade. I use push blocks, featherboards, a ZCI and splitter as appropriate but no guard. _I'm not advocating this for anyone else so don't anyone get their small clothes in a knot._
You can look now. 

"And that's all I got to say 'bout that." Forest. Forest Gump


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## Alf (21 Jun 2006)

Dave R":3bqz6cd4 said:


> I've suffered more injuries from handsaws and chisels than all my power tools combined.


So have I. But so far I've always remembered to stop before I removed a whole finger... :wink:

Cheers, Alf


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## Sawdust (21 Jun 2006)

Dave R":38vx18x2 said:


> It is interesting to me that if Brad's post were made on a US woodworkers forum....



Dave

Your point about the US forum interests me because that is one of my biggest confusion about this whole debate. To listen to some people over here, dados are more dangerous than atomic bombs and the suggestion is that you guys the other side of the pond have no idea about safety.

But my feeling is that if you guys were routinely being dismembered on dado equipped table saws, you must might say, hang on a bit these Brits are right, they are dangerous and stop using them.

Surely Americans value their fingers just as much as we do.

Having said that, the last time I was in Texas my colleague had three guns in his car, guns all over his house and a bullet making machine in his spare room!!!

Mike


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## Mike.C (21 Jun 2006)

> Dave R,
> 
> It is interesting to me that if Brad's post were made on a US woodworkers forum, the conversation would be related to which brand of dado set to buy and whether one should buy a 6" or an 8". There might be a little discussion about wobble blades but the majority of responses would be suggesting stacked sets.



Thats really what this subject is all about, where you are live and what way of cutting dado's you feel happy with. Lets face it, if the HSE had never mentioned dado head cutters, and like our brothers on the other side of the pond we had always used them, this thread would not exist.

Cheers

Mike


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## wrightclan (21 Jun 2006)

Dave R":fo2bzsiw said:


> I
> 
> I would love to see real riving knives on the common saws here in the US as you have there. they make much more sense than the splitters we have here. I wouldn't like to give up the longer arbor that I have now, though.
> 
> I've suffered more injuries from handsaws and chisels than all my power tools combined. )



I'll second both of those sentiments. I slipped with a chisel once and it went right into the middle of my left palm. Fortunately with not enough force to cause real damage, but my hand was sore for days. 

Riving knives are the real deal, they have more to do with safe ripping than any guard.

By the way Dave,

I grew up in Elk River (actually Otsego, which I guess is a town now, but was only a township when I was growing up.)

Nice to hear from a fellow Minnesotan.

Brad


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## SketchUp Guru (21 Jun 2006)

Sawdust":ax7lomb5 said:


> Surely Americans value their fingers just as much as we do.



I've always been attached to mine. All eight of 'em...and my thumbs, too. 

Brad, glad to find another Minnesotan here. You know, there are some Wrights on my mother's side of the family. She was from southern Iowa. Hmm....


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## ivan (22 Jun 2006)

I gather that part of the attraction of mountain climbing comes from conquering risk - no risk means no fun, no sense of achievement. Personally, that's *not* why I go into the workshop....so it's is of interest to me then, when because of an analysis of accidents, HSE express concern about cutting dados on a sawbench and point out that other methods are less prone to serious accident.

Using a RAS has its problems. You risk the blades running on into the work (unless specifically designed for that purpose); the wider cut pulling in more strongly than a single blade, stalling the motor and probably knocking the saw out of alignment.


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## Paul Kierstead (22 Jun 2006)

Sawdust":3h6uyo95 said:


> Same comments as others have made about braking, although I fail to see why, if a wheels can stay on a car under heavy braking (eg emergency stop with the wheels locked up), manufacturers can't make a blade stay on a saw where the braking is pathetic anyway.



I am sure the manufacturers _could_ but unfortunately they _don't_, and the theory of what could be done has no bearing on the safety of what *is* done. In any case, the arbor would have to be redesigned and I suspect the taste for all new designs of sawblades is low.

I have used a Dado (3/4" wide) and a router (3/4") a fair bit. There is no comparison in forces pushed back at the operator; the saw exerts considerably more force and has a *lot* more inertia, and also tempts you to cut deeply if it is a powerful saw. That said, I am not sure it is unreasonably unsafe in the single-person shop, but it can be tricky to use, especially on the exit. I would think that an overhead guard which rides (or very nearly) on the top of the wood would greatly increase the safety, although kickback concerns would remain. Personally I would consider a tilted blade to be much more dangerous then a dado, but then my saw doesn't have a riving knife either.

Incidentally, like most canadians, my saw does not have a brake and a dado goes for a loooong time to stop.


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## MikeW (22 Jun 2006)

John Elliott":2g2gmt4q said:


> I would be interested to know what the others who are reading this think about this, though.


I realize I am taking this out of the context of the rest of John's questions...

Here's what I think. It's all pretty silly in one sense. Use one, avoid one. What does it really matter?

The one I used in my shop was a little shy of $300 US. I haven't used it in a few years and in all likelihood won't ever again. Heck, my table saw is in storage anyway. I don't use that either. So why haven't I used it for so long? Because the only time I did use it is when working plywood or MDF. Anything less than a foot wide and I'll use the WoodRat. Even when having a stack of parts to dado, a guided router is incredibly fast. Guided in the sense of a clamp system. 

For most solid wood, I make dados by hand, which I don't use on solid wood furniture that often anyway.

So why all the babling? Well, I was asked what I thought :lol: 

Really it was just to illustrate that most of my local cabinet shops where I know the owner, only use tablesaw dados cutters when also cutting sheet goods. They do use them mounted in a RAS for lumber or components less than 24" wide. Set up is faster as it cuts on the up-side.

If I were to use the dado cutters again, I too would simply get a RAS and use it. I doubt I'll use sheetgoods where I need to cut dados ever again. And if the need arises, I'll probably use a guided router as it isn't worth setting up a table saw for it to me.

As to the issue of this thread: Safety? There are inherent risk in everything woodworking related. My advice is if you are not cutting dados in sheetgoods on a consistent basis, use a RAS instead. If you will do so once in a while, use a guided router. If you do intend on cutting dados in sheetgoods consistently, look for a safer, commerical solution.

Take care, Mike


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## RogerS (22 Jun 2006)

Apart from the Xcalibur, which other table saws in a similar price range will take a Dado?


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## wrightclan (22 Jun 2006)

Roger Sinden":2m8vnt1m said:


> Apart from the Xcalibur, which other table saws in a similar price range will take a Dado?



For a fair bit less, you could buy a used _Startrite,_ it will take up to 5/8", at a push 11/32". (There's a reduction in arbor diameter between the smooth section and the threaded section, to keep you from going any farther.)

Brad


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## Freetochat (22 Jun 2006)

The Hammer and Felder range can be specified for a dado set!


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## RogerS (22 Jun 2006)

Freetochat":3qs4k3hi said:


> The Hammer and Felder range can be specified for a dado set!



and how much would that be ? :wink:


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## wrightclan (22 Jun 2006)

ivan":2xftuk7k said:


> I gather that part of the attraction of mountain climbing comes from conquering risk - no risk means no fun, no sense of achievement. Personally, that's *not* why I go into the workshop....so it's is of interest to me then, when because of an analysis of accidents, HSE express concern about cutting dados on a sawbench and point out that other methods are less prone to serious accident.
> 
> Using a RAS has its problems. You risk the blades running on into the work (unless specifically designed for that purpose); the wider cut pulling in more strongly than a single blade, stalling the motor and probably knocking the saw out of alignment.



What an absurd implication--that those of us who use dado cutters do it for some kind of danger-seeking thrill. Quite the contrary, as I've been saying all along it is a safe procedure, as long as you use it sensibly, no more dangerous than many other woodworking processes. And no more dangerous than many day-to-day activities. ](*,) 

Brad


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## Anonymous (22 Jun 2006)

sawdust

A more appropriate question is why do you want a dado cutter? 
They offer no _real_ advantage over a router other than cutter life

They are slower to set up and change than a router cutter, do not leave as flat a bottom to the cut as the router and often require you to play with shims.

I have owned and use a Freud dado cutter set and do not consider then dangerous IF USED PROPERLY and with due care. Many injuries seem to be down to stupidity such as running 8*4' sheets over one :roll: 

However, I sold my cutter set and find the router with a guide a *far superior *and quicker AND potentially safer method of cutting dados - I would not consider going back to a dado head cutter which takes far too much time to swap with the saw blade and set up (I would have routed them all and glued them up by the time the dado head was in the saw :lol: )


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## Adam (22 Jun 2006)

wrightclan":18k3gwoc said:


> But that still does not address the issue that each of the teeth of a dado cutter are taking relatively small individual cuts,



True, but what about the inherent energy in the blade/motor of a saw vs the momentum in a cutter/router? They are vastly different.

Furthermore, assuming you are cutting a 1/2 deep dado, from the point that the saw blade tooth prodtrudes above the table, to the point it returns is just over 10cm. So, if the workpiece catches, the blade has a full 10cm to accelerate the wood over. Assuming the same corner catch on a router bit, I think (may have a dodgy calculation), that its only going to catch for 2cm (e.g. half a revolution).

So as far as I can see if the blade tips are able to catch, they have far longer to accelerate the wood, and their is far more stored energy in the table, and the blade is travelling faster.

Would you agree?

Adam


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## wrightclan (22 Jun 2006)

Adam":1cubxbwo said:


> wrightclan":1cubxbwo said:
> 
> 
> > But that still does not address the issue that each of the teeth of a dado cutter are taking relatively small individual cuts,
> ...



Yes, that's why it's more efficient at cutting a groove. It is still possible to use safely and is used safely by thousands everyday. ](*,) 

I don't get your assumption that more energy behind a cutting edge makes it inherently more dangerous. If that were the case, why don't we all use 500 watt routers?

Brad


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## johnelliott (22 Jun 2006)

wrightclan":1zlv5913 said:


> It is still possible to use safely and is used safely by thousands everyday.



I had stopped posting on this thread, though I'm still reading the contributions. I felt I had to respond to this particular statement, especially when it was accompanied with that emoticon, which suggested that you were having difficulty explaining something that seemed obvious to you, to others.

That statement above probably illustrates as well as anything else that has been said just what this whole argument is about- the case of most pro dado blade in table saw users is that they and others uses these things without accident every day, and that therefore they are safe.

On the other hand, the case that I and many others are trying to make is that just because an accident hasn't happened doesn't mean that the activity is inherently safe. 

John


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## Adam (22 Jun 2006)

wrightclan":1ceh1v36 said:


> I don't get your assumption that more energy behind a cutting edge makes it inherently more dangerous. If that were the case, why don't we all use 500 watt routers? Brad



At its extreme, I can grab a dremel router and stop it without injury. I know of at least one horrific case of an accident at a saw mill on a large circular saw. With or without gaurds, a low energy item simply can't do as much damage. It applies to most things, a tack hammer vs a claw hammer. I'm not saying thousands can't use something safely every day. Its the one in a million chance where it applies. A bad piece of timber, a hidden nail, a knot, shake or other fault that could not be seen from the surface. 

OK, all your point taken. How about a different perspective.

Imagine you had a piece of timber that looked perfect, you had all the guards setup, and you start cutting. Today is your unfortunate day, the world over, a thousand people were doing the same cut and it went fine. You have done this same task, on the same saw, for the last 20 years. You are confident in your own ability. Something unusual happens, something falls in your shop, the board has a nail, the missus walks in and knocks the plank, twisting it, you have a heart attack, a blackout, a fainting fit. Whatever.

Which would you rather be using. A dado cutter or a router? 

As above, but its your child doing it.




Adam


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## Kane (22 Jun 2006)

Are there any figures for actual accidents available? I would say that there is a risk inherent in any activity, if you say hiking is dangerous because there's a risk of snakebite you would be right but if you calculate the odds of actually getting bitten you may not be too concerned. What I find odd is that the use of dado cutters in the US is so high - surely in the land of litigation if a tool was causing a lot of injuries because it's design was so inherently dangerous someone would have sued a manufacturer by now (maybe they have lol)


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## Paul Kierstead (22 Jun 2006)

wrightclan":2vd1s21w said:


> If that were the case, why don't we all use 500 watt routers?



Because it wouldn't be effective. Not all choices are made solely on the basis of safety; that does not mean there are not safety differences to consider, and considering them does not mean "don't do it". A person has a choice to make and ideally the choice would be informed.

I have never had a router throw a good sized of piece of plywood at me; I have seen one try, but the attempt was poor. I have had a tablesaw do so. The energy difference is extremely obvious in practice. It doesn't mean the tablesaw shouldn't be used, but it is part of the informed choice.


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## matthew (22 Jun 2006)

I can't really offer much opinion because I don't have a TS and have never used a Dado set, but there is some interesting reading here:

http://www.woodworking2.org/AccidentSurvey/search.htm

I did a search on:
Tool: Tablesaw
Accident type: Needed medical attention
Keyword: dado

One notable quote:



> The doctors told me that the most frequent injuries they see are from dado blades.



Anyway, the router works fine for me, and will continue to do so!


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## Kane (22 Jun 2006)

Good site 

interesting to see total of 31 hits for router accidents needing medical attention and 153 for tablesaws (20 involving dados) definately a tool to respect!


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## wrightclan (22 Jun 2006)

Adam":28nu44ws said:


> [
> 
> 
> Imagine you had a piece of timber that looked perfect, you had all the guards setup, and you start cutting. Today is your unfortunate day, the world over, a thousand people were doing the same cut and it went fine. You have done this same task, on the same saw, for the last 20 years. You are confident in your own ability. Something unusual happens, something falls in your shop, the board has a nail, the missus walks in and knocks the plank, twisting it, you have a heart attack, a blackout, a fainting fit. Whatever.
> ...



What if one of those things happened, while travelling. Which would you rather be doing, walking, cycling or driving? I think I'd rather be walking. But that doesn't keep me from driving when the journey calls for it. I'm sorry, but I don't (and neither do you) live your life by the million in one chance.

I don't want my child to live that way either. 

I really think that all this fear over dado cutters is a fear of the unknown. Other than Scrit, how many of you, who are so adamantly opposed to them, have actually used one more than once or twice?

Brad



Brad


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## Jake (22 Jun 2006)

Feeling any pointlessness yet?



wrightclan":2t1lmns3 said:


> really think that all this fear over dado cutters is a fear of the unknown.



Or to turn that around 180 degrees, your lack of fear could be attributed to the complacency of having used one a lot without incident.


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## wrightclan (22 Jun 2006)

Jake":3h6f6fml said:


> Feeling any pointlessness yet?
> 
> 
> 
> ...



Yes it is pointless. ](*,) 

But no, I don't think I'm complacent--I use appropriate methods to control my workpiece or my tools, no matter what the operation. 

Brad


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## wrightclan (22 Jun 2006)

Kane":3bumffcj said:


> Good site
> 
> interesting to see total of 31 hits for router accidents needing medical attention and 153 for tablesaws (20 involving dados) definately a tool to respect!



You can respect it, without being afraid of it.

Brad


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## engineer one (22 Jun 2006)

this is i think becoming a boys pissing contest.  

the fact is we all take risks every day. we have to take
responsibility for our own actions.

for whatever reason the dado on a table saw is not allowed
in professional shops, and by extension therefore the manufacturers
will not sell it for amateur use. so arguing about its safety or otherwise
here is a bit pointless.

of more concern is whether the insurance that you carry, either for 
building or contents or in the case of pro's covers you for an 
accident with a machine that is not to the specification of the manufacturer,
and the cee certificate issued with it. 

we all modify our machines to some extent in the expectation that
we will always be fit enough to cope with the machine in the way we 
normally use it. but having discovered recently that i need to care for
my heart and some of the old broken bones in my back, i 
make sure i do not lift unwieldy bits of wood, or assemble things i 
cannot easily handle. this is good practice to stop me being totally 
stupid.

so i think about what i am planning to do, then take actions that will
ensure that i am working within the known limitations of my skills
and machinery. why would i bother to add risks to my daily tasks???

yes daily we take risks, but they are known. when working on 
your own in your own workshop, what about your own physical
abilities?????

i do not remember many other threads that offer so little help, and so
many foolish comments. i thought we were better than that.
:twisted: 

paul :wink:


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## wrightclan (22 Jun 2006)

I'm truly sorry, if anyone feels that this has been a pissing contest. I did not intend any of my comments to be taken that way. 

Sawdust asked a question about the safety of dado cutters. I was trying to point out that (as with any endeavour) danger *almost* always comes when we (or someone else) are using something improperly. The danger is not really inherent in the tool itself. 

And that in those instances where danger comes from something completely outwith anyone's control; then to take that miniscule risk with a dado cutter is no more irresponsible than the risks of daily life.

Brad


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## wizer (22 Jun 2006)

hehe dont worry wrightclan, you could bring this topic up next week and still get the same heated debate. I almost get withdrawal symptoms if i dont read a dado argument every now and then   

my 2p, as stated in all the other dado threads: if i had a TS that took a dado I would try it and if I liked it, i'd use it.


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## wrightclan (22 Jun 2006)

I'll just go back to my original stance on the issue:

:-$ [-( :-# 

Brad


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## Sawdust (22 Jun 2006)

Crikey, I only paid for the 15 minute argument


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## Alf (22 Jun 2006)

Yeah, but you get 15 minutes from _everybody_... :wink:


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## mr (22 Jun 2006)

Sawdust":fxi8rwvb said:


> Crikey, I only paid for the 15 minute argument


No you didn't


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## Sgian Dubh (22 Jun 2006)

Not from me Alf, well not yet. I'd foresworn to never again enter a dado debate but here I am breaking that rule. I'll simply relate what I've seen and leave people to decide what's right for them.

I'm not a dado blade user but I lived and worked in the USA as a furniture maker and/or workshop manager for ten years in four different businesses. I witnessed, if I recall correctly, either four or five dado blade, er, urhm, incidents of varying degrees of seriousness. And there were also two or three fairly serious table saw incidents largely caused by lack of crown guards and splitters. In the latter cases I suspect things were sometimes not helped because of the use of the long rip fences favoured in US style woodworking. 

Still, each to their own. However, now that I'm living and working again in the UK I really have no hankering to use a dado blade in a table saw. 

That's all I'm saying on the subject. Slainte.


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## wizer (22 Jun 2006)

Sgian Dubh":3iryw70i said:


> use of the long rip fences favoured in US style woodworking.



Can you expand on that? not something I have come across before. Longer as in longer than the table?


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## Kane (22 Jun 2006)

wrightclan":z2m8ocq2 said:


> Kane":z2m8ocq2 said:
> 
> 
> > Good site
> ...



Very true


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## Adam (22 Jun 2006)

engineer one":h05a2fbb said:


> this is i think becoming a boys pissing contest.



Nah, I'm just playing devils advocate on this thread. As normal dado threads get heated, therefore moderators have to watch them carefully, and in turn, I might as well post seen as i have to read each post. In reality, by having two of us play ping pong I think helps get all the facts out in the open. Its a pleasure to hear someone else view on all topics, and dado's and safety is a topic which, admittedly has stronger views but none of them are any the less relevant. We talk just as much on dust, blade sharpening, etc. 

We may not change our individual views, but some people may understand it more, which is, in effect, the whole purpose of the forum. A forum of views.

Adam


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## Jake (22 Jun 2006)

WiZeR":zivvwugk said:


> Sgian Dubh":zivvwugk said:
> 
> 
> > use of the long rip fences favoured in US style woodworking.
> ...



Longer as in not stopping at the blade, and instead being the whole length of the table

Worth a read, and ignoring Clarkson-like scorn, these people derive their ideas from when things have gone for people who presumably thought it would never happen to them: http://www.hse.gov.uk/pubns/wis16.pdf


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## engineer one (22 Jun 2006)

adam all i was saying that it seemed to be getting to my risks are
bigger than your risks, and that is where the contest seems to be.

having driven at over 200 mph, and pulled large wheelies on
bikes i understand risks, but that was on machines i had
built not ones i had bought and wood i knew nothing about.

paul :wink:


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## Sgian Dubh (22 Jun 2006)

Kane, ancient style UK ripsaws had long fences that stretched the full length of the table alongside the saw blade. Typically there was a rail front and back and the fence stretched from rail to rail. It locked in place on these rails with a cam action lever on the infeed side. Decades ago when I started in this game they were still quite common on older pre-WW2, WW2 and 50's Wadkins for example.

Similar long fences are the most common type in the US with the most popular brand being the T locking style Beisemeyer (sp?) fence itself and a bunch of clones based on it.

The problem with this kind of fence in ripping is that when the saw kerf in the wood opens after the cut due to the release of internal stresses this can force the dimensioned piece of timber on the right side of the blade tight against the rear upcutting teeth. This is kickback territory. Where a riving knife is fitted and a crown guard is in use the kickback is less likely to occur because the riving knife helps prevent the wood making firm contact with the rising rear teeth. However, in the US most users use neither a splitter (riving knife equivalent but iffy) nor a crown guard. The wood in the situation I described is forced into tight contact with those rear upcutting teeth which can easily result in kickback.

A short ripfence (the style used in the UK) allows a piece of wood similarly bending to bend away from the blade.

I witnessed kickback off dado blades too. The wood closed on the blade after internal stresses were released resulting in the wood firing back at the operator. Similarly, wood that drifted away from the long rip fence kicked back at the operator-- it's almost all down to those upcutting rear teeth. True, hold downs and other safety gear could have likely prevented the mishaps in both cases. The operator chose not to set any up. 

I do say if anyone wants to use a dado blade, do at least be very wary of them. Slainte.


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## Noel (22 Jun 2006)

engineer one":3vftwztn said:


> adam all i was saying that it seemed to be getting to my risks are
> bigger than your risks, and that is where the contest seems to be.
> 
> having driven at over 200 mph, and pulled large wheelies on
> ...



Interesting comparison as Marco Melandri might understand.
These days a stacked dado is waaay safer that travelling at 2 ton.

Noel, who hasn't exceeded 185, in a car.


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## engineer one (23 Jun 2006)

yea but i did it on proper tracks and roads, not
overtaking some horse and cart in the middle of derry :lol: :lol: :lol: :lol: 

and boy those autobahns in the old days :twisted: :twisted: :twisted: 
paul :wink:


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## Noel (23 Jun 2006)

Autobahns were and still are fun, although the de-restricted bits are few and far between these days.
That horse and cart you mention, what about it? Too fast for you was it?

Noel


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## engineer one (23 Jun 2006)

no mate but it was like the old story,
you know if i were you i would not be starting from here.

sadly it happened to me in dublin from a hotel :lol: 

actually it was when the horse pulled a wheelie that i got really 
scared :twisted: :twisted: :lol: :lol: 

and coming down the mountains from strasbourg along to luxembourg
now that can be fun in the fog and ice [-X [-X 

paul :wink:


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## Anonymous (23 Jun 2006)

You must enter a message when posting


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## wrightclan (23 Jun 2006)

Sgian Dubh":1lul29mx said:


> Kane, ancient style UK ripsaws had long fences that stretched the full length of the table alongside the saw blade. Typically there was a rail front and back and the fence stretched from rail to rail. It locked in place on these rails with a cam action lever on the infeed side. Decades ago when I started in this game they were still quite common on older pre-WW2, WW2 and 50's Wadkins for example.
> 
> Similar long fences are the most common type in the US with the most popular brand being the T locking style Beisemeyer (sp?) fence itself and a bunch of clones based on it.
> 
> ...



Not going to break my :-# on the *D* issue.

Just replying to some general tablesaw comments. I have a UK saw which is nowhere near as old as Sgian Dubh mentions, and it has a full-length fence. I've also seen alot of new saws marketed in the UK, which do, and not just American clones.

I really think that if American saws had proper riving knives and guards which detach and attach easily to the riving knife; then they would get used a lot more. You have to realise how poorly designed and unnecessarily complex American style guards/splitters are to understand why no one uses them.

Those Americans who know what a proper riving knife is, are begging for them. I don't know why more manufacturers aren't doing it. BTW at least one American company--_Laguna_, is doing it. Oh, I just remembered, _Sawstop_ is, as well.

Brad


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## Sgian Dubh (23 Jun 2006)

SawStop is a new'ish brand in the US offering table saws with a riving knife and crown guard. The other element in their package is the almost instant braking device available should flesh come into contact with the blade. By all acounts most reviewers and/or users are happy with the tool. There's some whinges by some potential buyers about price, but that's a different issue.

Powermatic (and Grizzly I think) are both now offering an improved riving knife and crown guard configuration for the US market. Certainly both are now offering new developments such as sliding table saw that would be familiar to European woodworkers.

I have seen some saws at the low end here in the UK with long rip fences as you mention. Personally I wouldn't touch one with a barge pole unless there is a configuration where the fence can be set up for the short rip style. I see that some have that capability, but I can't say for all of them. Slainte.


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## wrightclan (23 Jun 2006)

Sgian Dubh":3fsyz3wd said:


> Personally I wouldn't touch one with a barge pole unless there is a configuration where the fence can be set up for the short rip style. I see that some have that capability, but I can't say for all of them. Slainte.



Simple solution: a facing of ply or MDF which does not go the full length of the fence. 

BTW,after my last post I remembered some of the high end _Grizzlies _have riving knives. What I can't understand, is why they don't fit them to all their saws; presumably it's a cheaper option as it's a much simpler device with fewer parts, and it's attached to the trunnions. 

Brad


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## Alf (23 Jun 2006)

wrightclan":2mc4lluw said:


> Sgian Dubh":2mc4lluw said:
> 
> 
> > Personally I wouldn't touch one with a barge pole unless there is a configuration where the fence can be set up for the short rip style. I see that some have that capability, but I can't say for all of them. Slainte.
> ...


The Maxi (cough, spit) solves the problem with a little adjustable L-shaped length of plastic held with a thumbscrew to the main fence. Only needs one hole tapped in the fence iirc, if anyone feels like applying the modification themselves.

Cheers, Alf


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## wrightclan (23 Jun 2006)

Sgian Dubh":3l1zuohh said:


> I have seen some saws at the low end here in the UK with long rip fences as you mention. Personally I wouldn't touch one with a barge pole unless there is a configuration where the fence can be set up for the short rip style. I see that some have that capability, but I can't say for all of them. Slainte.



I have a _Startrite_. Not sure of the age, but quite sure it's well post-50's. _Misterfish_ has a _Wadkin_, which is surely well post-50's. ( He has a recent post with a photo). Both of our saws have full-length fences. I wouldn't call them high-end, but I also, certainly wouldn't classify them as low-end. They're both well-made solid British saws. Perhaps, you having worked in industrial settings, your idea of low-end and mine are different. (By the way, I have worked in industrial settings, repairing and installing safety equipment for metalworking machines, just not an industrial woodworking setting.)

Brad


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## wrightclan (23 Jun 2006)

Is this a low-end saw?

http://www.axminster.co.uk/recno/2/product-Rojek-KPF300-Saw-and-Spindle-Moulder-32087.htm :-k :?


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## Freetochat (23 Jun 2006)

Mr_Grimsdale":3vx6l4eh said:


> Not trolling! Just want to point out that a wobble saw such as this http://www.axminster.co.uk/name/wobble+ ... -20237.htm does everything that a dado set does AFAICS but with absolutely non of the problems - real or imaginary.
> I always find it trouble free and a pleasure to use. I use it mostly for slots 13x13mm in panel door styles and rails.
> Fast , quiet, clean cutting, precise, easily adjustable, dust free, no kick back risk and more. Everyone should have one!
> 
> ...



But isn't this wobble saw only advised for a spindle moulder. That being the case, there are many groovers, adjustable or fixed, available. Therefore it will not do the same job as a dado which seems to primarly do crosscut housings.


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## johnelliott (23 Jun 2006)

wrightclan":3222enxj said:


> Is this a low-end saw?
> 
> http://www.axminster.co.uk/recno/2/product-Rojek-KPF300-Saw-and-Spindle-Moulder-32087.htm :-k :?



From the context of your previous post I presume you are asking the question from the POV that the fence appears to be of the full length variety.
I have a recent Startrite saw (made by Rojek) which is similar (without the spindle moulder) to the model you are asking about. I would say that it is not low-end. Also the alloy extrusion which is fitted to the fabricated steel fence can be adjusted so that the it stops wherever one wishes in relation to the blade. When ripping hardwood I set it so that it stops in line with the back of the blade. This means that in this case it is a short fence. When cutting plywood I normally set it so that it is in effect a long fence

John


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## Scrit (23 Jun 2006)

My, haven't I missed some fun! But I'd still like to add a few of comments:



Sawdust":3vqhlb74 said:


> ...., although I fail to see why, if a wheels can stay on a car under heavy braking (eg emergency stop with the wheels locked up), manufacturers can't make a blade stay on a saw where the braking is pathetic anyway.


Because a car has 4 or more nuts to hold it on - a blade has one, designed in such a way that when the blade is accellerated from rest the centrifigal force will tend to tighten the nut onto the blade. Brake a blade and it will undo the nut - which is why ALL industrial/larger saws now have pinned arbors to stop the unscrewing of the nut by the blade under braking. Under 10 inches there is generally insufficient kinetic energy stored in the blade for this to happen. And my saws, including a 16in rip saw all brake to stop in under 5 seconds.



JPEC":3vqhlb74 said:
 

> Refering to questions posed on Norm's site, the only reason dado cutters do not conform to European standards is that they take longer to come to a stop after the saw is switched off, than is permissable.


That and the little question of stacked dado heads over 15.5mm (BSI standard) not being of anti-kickback design (mandatory on most tooling sold in the EU since 2000). The other thing to quote from the HSE is _"Tools which belong to a tool set, or are part of a stacked tool..... .....should be designed in such a way as to prevent the parts being used individually, eg by using pins_". This also makes the sale and use of stacked dado sets questionable. Oh, and Norm generally doesn't discuss guarding, either.  



Mr_Grimsdale":3vqhlb74 said:


> PS why the mention of 'riving knife' with ref to a dado cutter - it wouldn't serve any purpose even if you could fit one. These cutters make a slot, not a through cut, so there is no risk of the work binding on the blade as the sides can't spring together.


On saws with suspended crown guards where you have a short riving knife, such as panel saws, which do not extend above the blade (rather like those on a hand circular saws) the riving knife serves another function - to minimise the risk of picking-up on rising teeth if the work is accidentally tipped, something Sgian also mentions. Hence my preference for a Shaw-type down pressure guard or power feeder.



Kane":3vqhlb74 said:


> What I find odd is that the use of dado cutters in the US is so high - surely in the land of litigation if a tool was causing a lot of injuries because it's design was so inherently dangerous someone would have sued a manufacturer by now (maybe they have lol)


My understanding is that American firms work on the basis that they can legally defend the _status quo_ at lower cost than a novelty (i.e. a new concept). This has been done to death on a number of fora in the USA, such Taunton's Knots. There are genuinely an increasing number of people in the USA who are aware of safety issues and who are actively seeking more European style safety solutions.

Personally, I think that Sgians comments on the subject of dados sum it up very well indeed.

Of anyone is interested in the topic of short rip fences Barb Siddiqui and Richard Jones published an excellent article subject on Badger Pond a few years back. The same site also has good article on DIY overarm guards here

Scrit


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## Sgian Dubh (23 Jun 2006)

Rojek don't make low end machines. They make lower middle range professional or upper range amateur use saws. Hammer is in about the same bracket, probably a bit lower. Hammers' big brother, Felder, makes upper mid range kit, SCMI about the same and perhaps slightly above and, of course, Altendorf are top end in the dedicated panel handling sliding table saw bracket-- they're actually pretty poor for ripping solid wood due to access problems. Slainte.


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## Kane (23 Jun 2006)

Scrit,
I was thinking more of individuals rather than businesses - just trying to get into woodwork so this is the only forum I've been on  I think most of us will be familiar with individuals in the US carrying out some blatantly ridiculous practice with something then suing the maker for millions of dollars, or do the dado suppliers in the US emphasise the need for appropriate guards etc?


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## Jake (23 Jun 2006)

Kane":bz3qz5qf said:


> Scrit,
> I was thinking more of individuals rather than businesses - just trying to get into woodwork so this is the only forum I've been on  I think most of us will be familiar with individuals in the US carrying out some blatantly ridiculous practice with something then suing the maker for millions of dollars, or do the dado suppliers in the US emphasise the need for appropriate guards etc?



US woodworking industrial injury statistics (deaths/100,000 workers) are worse than in the UK by a factor of about 2, at least for fatal accidents. There were no UK stats for non-fatal injuries in the document I was looking at, so no comparison available there. I can't now find the document, but it is buried in the HSE site somewhere.


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## Sawdust (23 Jun 2006)

Scrit":1y136ua8 said:


> My, haven't I missed some fun! But I'd still like to add a few of comments:
> 
> 
> 
> ...



Actually those nuts hold the wheel onto the hub, the hub is held in place with a single (castellated I believe it's called) nut. Nit picking I know but from an engineering perspective, it could be achieved on a table saw arbour if the manufacturers chose to do so.

It has been an interesting couple of days and I'm glad I started the thread!

My initial question was an attempt to find out if I was completely overlooking something in terms of dado safety (or lack of it) but it seems in summary the issues are:

Potentially coming off a braked arbor.
The standard guard cannot be used.
The riving knife is ineffective.

It seems to me that the only one which cannot be overcome is the riving knife issue which as I understand it, leads to potential kickback dangers which I completely agree should not be taken lightly.

Having said that, the reason I asked in the first place was that the overwhelming dislike for dado cutters was because there really was something I had overlooked.

Having read all I've read, I do intend to go ahead and buy one, try it out on the RAS and see how I get on. 

Cheers
Mike


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## RogerS (23 Jun 2006)

Sawdust":1p3dc2om said:


> It seems to me that the only one which cannot be overcome is the riving knife issue which as I understand it, leads to potential kickback dangers which I completely agree should not be taken lightly.



I may have got the wrong end of the stick here but isn't the point of the riving knife to keep the two pieces of wood on either side of the cut apart when you are cutting completely through the stock? So that the rising blade doesn't kick back the wood.

But when you use a dado you are only cutting through part of the stock and so a riving knife isn't needed in this instance?


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## SketchUp Guru (23 Jun 2006)

The issue of the riving knife being ineffective in conjunction with a dado set continues to come up. I can't see how a riving knife would make any difference when using a dado set. As I understand it, a riving knife is supposed to keep the kerf from closing up on the rising teeth at the back of the blade during a rip cut. A dado cutter isn't used for through cuts so there's no kerf to close up. 

My experience has always been with a full length fence against which the stock bears until beyond the blade. Maybe the riving knife is used to keep the stock way from the blade with a short fence? I don't know.

From the Wikipedia: A dado is a slot or trench cut into the surface of a piece of machineable material, usually wood. When viewed in cross-section, a dado has three sides. _A dado is cut across the grain and is thus differentiated from a groove which is cut with the grain._

From that definition, which is the one I learned years ago, The rip fence doesn't come into play anyway. Just nitpicking. :lol:


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## Scrit (23 Jun 2006)

Kane":199fmksx said:


> I was thinking more of individuals rather than businesses....


Actually the comments I recall were from discussions amongst hobbyists rather than professionals.

Scrit


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## Scrit (23 Jun 2006)

Roger Sinden":f9ijj1hn said:


> Sawdust":f9ijj1hn said:
> 
> 
> > It seems to me that the only one which cannot be overcome is the riving knife issue which as I understand it, leads to potential kickback dangers which I completely agree should not be taken lightly.
> ...


In the case of a saw with an overhead guard, such as an Altendorf or Felder panel saw or a large rip saw, for example, it also serves the purpose of safeguarding the operator from kickbacks caused when work is accidentally lifted whilst pushing through - and believe me that does happen. You can get exactly the same on a dado head

Scrit


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## RogerS (23 Jun 2006)

Scrit":1yw9b773 said:


> In the case of a saw with an overhead guard, such as an Altendorf or Felder panel saw or a large rip saw, for example, it also serves the purpose of safeguarding the operator from kickbacks caused when work is accidentally lifted whilst pushing through - and believe me that does happen. You can get exactly the same on a dado head
> 
> Scrit



Scrit - not doubting you for one moment but can you explain a bit further as I don't see how the riving knife will safeguard the operator in this case. 

Thanks
Roger


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## Scrit (23 Jun 2006)

Sawdust":1x86ti6h said:


> Actually those nuts hold the wheel onto the hub, the hub is held in place with a single (castellated I believe it's called) nut. Nit picking I know but from an engineering perspective, it could be achieved on a table saw arbour if the manufacturers chose to do so.


And a castellated nut doesn't go on and come off as often as a nut on a saw and would have a clevis pin through it, wouldn't it? For our machines this would prove impractical. In any case the industry _standardised_ on an approach many years ago for conventional sawing - two pins either side of the arbor OR a lock nut OR a pinned cutter set OR a keyed arbor. They're out there and in use on European kit (since the early 1990s). Dado heads are increasingly an anachronism as there are other faster, safer, more appropriate approaches available to us.

What you have completely overlooked is the tooling design. A "safety" head has the advantage over a stacked saw set that it will tend to throw a finger, hand, etc. out from the cutter in the event of a contact - a stacked set will do the opposite and will pull the finger, hand, etc. aggressively inwards. Hence the need for effective guarding. This is why the few European manufacturers selling compliant tooling - Kity, Scheppach and Felder, etc (and formerly deWalt, too) - have adopted a non-stacked saw / interlocking cutterblock approach rather like the tooling used on spindle moulders, and which incidentally on a RAS is much less prone to climbing the work (from experience of both).

Scrit


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## Sawdust (23 Jun 2006)

Scrit":3nsd48xb said:


> Sawdust":3nsd48xb said:
> 
> 
> > Actually those nuts hold the wheel onto the hub, the hub is held in place with a single (castellated I believe it's called) nut. Nit picking I know but from an engineering perspective, it could be achieved on a table saw arbour if the manufacturers chose to do so.
> ...



Scrit,

I don't understand this, why would one push the fingers away and one pull them in, is it something to do with the angle of cut?

Thanks
Mike


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## Kane (23 Jun 2006)

Scrit":qtxgncgb said:


> Kane":qtxgncgb said:
> 
> 
> > I was thinking more of individuals rather than businesses....
> ...



Interesting - maybe US woodworkers aren't the suing type


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## SketchUp Guru (23 Jun 2006)

Kane":39s6txp6 said:


> Interesting - maybe US woodworkers aren't the suing type



Nah, that's not true. I don't think woodworkers in the U.S. are the sorts to sue unless maybe they are working in a commercial or school situation. 

It never occurred to me to sue anyone when I slit myself with the chisel. 

Of course one could sue and win if they spilled hot coffee in their lap while driving their car away from the drive through window at McDonalds. :roll:


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## Kane (23 Jun 2006)

Dave R":1fgggclt said:


> Kane":1fgggclt said:
> 
> 
> > Interesting - maybe US woodworkers aren't the suing type
> ...



Exactly my point lol


----------



## Scrit (23 Jun 2006)

Sawdust":3tnwnc0m said:


> I don't understand this, why would one push the fingers away and one pull them in, is it something to do with the angle of cut?


In limiter tooling (as in a "safety head" on a spindle) the "gullet" in front of the cutter face is fairly small, the body of the cutter is circular and in addition you have only two or four cutters. If you manage to jamb a digit into such a cutterblock the distance you can push into the gullet (and by default the amount of "bite" a cutter can take out of timber when machining) is limited. The body of the cutter behind the cutter being round and the direction of the block rotation will tend to throw the digit back out towards the infeed side of the saw - a combination of friction contact between the hand/digit and centrifigal force. A stacked dado set on the other hand has no body behind the individual rakers to do this, does not have a limited "gullet" and that combined with the attack angle of the raker means the tendency id to pull inwards/down wards.

I've experienced this first hand with a router cutter on an overhead router - 1/30 second contact approximately with a 2-flute cutter going at 20,000 rpm = 22 lacerations and 13 stitches. I think that a non-limiter cutter would potentially have amputated my left thumb. I also know two guys who've lost digits in circular saw accidents because saw blades seem to have a tendency to pull-in.

RASs have a different set of problems. If you trap a finger between the workpiece and the dado set, even if that is a safety head, the saw will tend to "climb" the work - and your finger - and you will be lucky not to get away without an amputation. This is why the HSE advice is that dado heads on RASs must be close guarded to within a few millimetres of the surface of the work piece. 

What you don't experience on a RAS is kickback - what you do get instead is climbing. The old way around this used to be to fit a air/hydraulic piston onto the arm to "smooth" out the cut - for us trades types these are banned now, I believe. I've noticed from spindle moulder work that it is almost impossible to "overfeed" a limiter cutter block as the body prevents you doping so and I've no doubt that the same is true of a safety grooving head on the RAS. Incidentally for safety's sake I'd recommend fitting a spring return mechanism onto your RAS - that will return the saw head to the home or parked position at the rear of the saw in the event of you letting go of the handle for any reason.

Scrit


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## Scrit (23 Jun 2006)

Roger Sinden":1t27hr2i said:


> ...not doubting you for one moment but can you explain a bit further as I don't see how the riving knife will safeguard the operator in this case.


On a panel saw with an overhead guard (e.g. Felder/Altendorf) or a large rip saw similarly equipped it is possible to "deep", e.g. saw a groove without breaking through and with the riving knife left in position during the cut. This is because the riving knife is wider than the body of the saw and nattopwer than the kerf. On the machines I've mentioned it is also a few millimetres "shy" of the top centre of the blade in height. I sometimes use the panel saw to saw 3.2mm wide slots for thin back material this way and you need to take care that you don't accidentally lift the workpiece as you push it across the saw - doing so can tip the work down onto the rising teeth, a kickback situation if the riving knife were not present. If we accept that it is probably impracticable to install and adjust a riving knife with a dado set on a saw, then the way to avoid this form of kickback has to be to use a hold down (Shaw guard) or a power feeder to ensure that the workpiece cannot be accidentally lifted/tilted

Scrit


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## Sawdust (23 Jun 2006)

Scrit":1fs3sw10 said:


> Sawdust":1fs3sw10 said:
> 
> 
> > I don't understand this, why would one push the fingers away and one pull them in, is it something to do with the angle of cut?
> ...



Thanks for that explanation



Scrit":1fs3sw10 said:


> I've experienced this first hand with a router cutter on an overhead router - 1/30 second contact approximately with a 2-flute cutter going at 20,000 rpm = 22 lacerations and 13 stitches. I think that a non-limiter cutter would potentially have amputated my left thumb. I also know two guys who've lost digits in circular saw accidents because saw blades seem to have a tendency to pull-in.



Ouch!



Scrit":1fs3sw10 said:


> RASs have a different set of problems. If you trap a finger between the workpiece and the dado set, even if that is a safety head, the saw will tend to "climb" the work - and your finger - and you will be lucky not to get away without an amputation. This is why the HSE advice is that dado heads on RASs must be close guarded to within a few millimetres of the surface of the work piece.



Whenever I use my RAS, I never allow my left hand to get in the line of the blade, if I'm machining a small piece, I hold it in place with push stick. With a dado in place I would adopt the same practice. I allow quite a safety margin when doing this as if there is a nasty dig-in it can jump forwards. This can be pretty unnerving but at least it doesn't launch the wood at the operator.

Mike


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## wrightclan (23 Jun 2006)

Dave R":2pv2ffjr said:


> Kane":2pv2ffjr said:
> 
> 
> > Interesting - maybe US woodworkers aren't the suing type
> ...



I'll second that. I was raised the non-suing type. About 16 years ago (doesn't seem that long :shock: ), I was in a cycle race, when I was forced off the road about 10 yards from the finish, by another cyclist. There were a couple of things that made the crash far worse than it otherwise would have been. First, the road had just been resurfaced, leaving about a six inch drop from the tarmac  onto the gravel shoulder. More importantly, there was a car parked at the side near the finish. My front wheel went into the wheelwell of the car, throwing me back onto the road for about five other cyclists to come tumbling over me. I required medical attention, and my expensive bike was ruined. 

Now it is against USCF (United States Cycling Federation) regulations to have a car parked that close to a finish. Several of my teammates kept reminding me of that rule. It never occurred to me, until years later, that they may have been hinting that I could have pretty good grounds for a lawsuit. To me, the crash was just part of doing the sport I loved. Two weeks later, I was racing again.
Brad

By the way, Dave, the race was in Cottage Grove


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## johnelliott (23 Jun 2006)

Dave R":3u41bgsn said:


> Of course one could sue and win if they spilled hot coffee in their lap while driving their car away from the drive through window at McDonalds. :roll:



Anyone who wants to know more about the most famous case in American legal history could have a look here
http://freerepublic.com/focus/f-chat/1287038/posts
It's quite short but very interesting.

John


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## SketchUp Guru (23 Jun 2006)

wrightclan":3p097xjd said:


> By the way, Dave, the race was in Cottage Grove


And you didn't invite me to watch? :roll: :lol: I was living in Woodbury then.


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## wrightclan (23 Jun 2006)

Dave R":2gdenow1 said:


> wrightclan":2gdenow1 said:
> 
> 
> > By the way, Dave, the race was in Cottage Grove
> ...



What, to watch me crash and burn? [-X 

I've heard about you types. The ones who watch the Tour de France just for the sprint crashes--my brother is one of those :roll: :lol: 

I was living in Burnsville at the time. I may have cycled by your house a couple of times, while out training.

Brad


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## Scrit (23 Jun 2006)

wrightclan":6rq0zt4b said:


> What, to watch me crash and burn?.....
> 
> .....I was living in Burnsville at the time.


Might I say, "how appropriate"? :lol: :lol: 

Sorry, Mike, OT. I'll get me coat

Scrit


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## wrightclan (23 Jun 2006)

Scrit":31b4c05t said:


> wrightclan":31b4c05t said:
> 
> 
> > What, to watch me crash and burn?.....
> ...



Stepped right into that one  :lol: 

Brad


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## Anonymous (23 Jun 2006)

Dave R":3detewxe said:


> The issue of the riving knife being ineffective in conjunction with a dado set continues to come up. I can't see how a riving knife would make any difference when using a dado set. As I understand it, a riving knife is supposed to keep the kerf from closing up on the rising teeth at the back of the blade during a rip cut. A dado cutter isn't used for through cuts so there's no kerf to close up.



Yep. that's true.

I still say that my dado took as long to mount and set up in the saw as a router takes to change the bit, clamp the guide, cut the dado and glue the wood. 

I see no reason for using a dado head cutter set and got rid of mine.


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## Inspector (23 Jun 2006)

I suppose it's a good thing that these forums were not in existence when I started woodworking 30+ years ago. I probably wouldn't have started. That said, being on this side of the pond, I have 2 dado cutter sets for my saw. They are a lot quieter than a router and even compared to a normal blade. 

The first is a cheap 6" wobble type that I never really liked. Not because of safety reasons, but because it doesn't leave a nice edge when crosscutting (splinters). It is also, because its was cheap, a pain to set the width. Maybe I might feel different with some of the newer high end blades that are now sold. I use it more for cutting coves than for dados. 

My second set is a 10" (yes they are available in that size here) stacking type that I bought a few years after the wobbler. It leaves a clean cut and is simple to set the cut width. I like it and I'm not going to let anyone pry it out of my fingers as long as I still have them. 

I don't use sheet goods very often, so my use of the blades is on hardwoods when plowing grooves. And while I understand why most use routers for that kind of cut, when you want to plow a 2" or deeper groove a router takes too long. I do understand the risks that can be encountered with this kind of cutting (especially the wood closing around the blade) so I stay mindful of the hazards and work accordingly. My choices are not for others and If you don't have a lot of time on saws then don't get your experience with a dado. 

Since I have never used splitters (they were not with or were so badly designed and weren't used) or riving knives I have learned to work without them. If decent ones were on I would use them. North American makers started out making saws without them in the dark ages, and in spite of Americas claims to be innovators and on the leading edge they are extremely resistant to change. They didn't want to put on riving knives because it would mean making new castings etc. And that costs money and if you don't have to, then why bother. They like the expression "If it ain't broke, don't fix it". 

A riving knife could probably be made for a stacking dado set if it already has a good one with the saw. With a few holes through the main knife, and knife profiled leaves matching the thickness of the blades. Then what ever stack and shims are selected for the blade, the corresponding leaves are added to the riving knife to proved the same width. If the knives are not strong enough to add to.......then....... never mind. 

I have used dados on the RAS, but prefer the table saw because it is more accurate. The RAS types that I've had access to are of the hobby/contractor type and not all that rigid. 

There are as many sides to a debate as there are participants, and I'll let you be the judge of your own choices and actions. I may however make a couple signs to hang at the entrances to my shop when dadoing stating. "controversial WOODWORKING IN PROGRESS. NO BRITS ALLOWED". 

:lol: :lol: 

The one thing that nobody has thus far mentioned is that a dado set move a lot more air and is cooler to work around in the summer.


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## johnelliott (23 Jun 2006)

Inspector":8txq92m2 said:


> when you want to plow a 2" or deeper groove a router takes too long. I do understand the risks that can be encountered with this kind of cutting (especially the wood closing around the blade) so I stay mindful of the hazards and work accordingly. )



I am very interested to know why you would want to plough a 2" or deeper even groove in hardwood.

I would also be interested to know how exactly one works when mindful of the hazards.

John


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## wrightclan (23 Jun 2006)

wrightclan":eyf0nsas said:


> Scrit":eyf0nsas said:
> 
> 
> > wrightclan":eyf0nsas said:
> ...



It gets worse--I lived on _Burns_ville Parkway, in _Burn_ingham Apartments (affectionately known to some residents as "The Flaming Swine.") :roll:


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## Inspector (24 Jun 2006)

johnelliott 
You asked why I would want to make deep grooves. It's the method I learned from my father (70 years working with wood at this point) when making frame and panel doors. The groove for the panel is cut normally, then instead of mortising for the tenon you raise the blade to the length of the tenon and cut with the dado far enough to accommodate the width of the tenon. The arc after is hidden by the panel when it's all glued together. Modern glues are more than up to the task of holding the joint against the loads encountered unless someone is deliberately trying to break it and they will have to work pretty hard to do that. I will add that I would not use this for an exterior application but for interior doors and cabinet work it's fine, and it's easier for larger doors than for small work. 

As for "being mindful of the hazards" I stay out of the line of fire in the event of a kickback (hasn't happened yet with the dado), using push sticks, not putting yourself in a position of being potentially unbalanced over the blade, and not having the hands in such a position as to get pulled back into the blade or over it if the wood isn't suddenly there. One other thing is to be willing to let the wood go and jump back if at any point the 'heebee jeebees' tell you something isn't right. It's better to bail out and replace the wood than to keep going against your instincts and try to overpower a power tool. That may not be a satisfactory answer for you but you are the one to decide what works best for yourself and work accordingly.


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## SketchUp Guru (24 Jun 2006)

Brad, you might have done so at that.

Say, back on the subject of dadoes, I'm curious as to how one might go about making something such as the grate I drew in Mark's Slatted Mat thread without using a dado set on a saw. This is a traditional way to make grates for boats.

As drawn the notches are 3/4" wide and 3/4" deep. Typically (in the US, anyway) the dadoes would be cut in wider stock and then the stock ripped down to the width of the dadoes. In the case of the grate I drew, and allowing for saw kerfs you would need about 30" of stock width just to make the notched pieces. Lets called it 6 pieces of 5" wide lumber. I drew 13 notches which works out to 390 linear inches or 32.5 feet of cut. Commonly teak would be used for a grate of this sort although other woods such as Ipe or some other tropical hardwood might be used.

Considering that you probably couldn't make a 3/4" x 3/4" cut in one pass, how would you make these? Three passes? Would you set up a box joint sort of registration jig on a router table and make a series of shallow passes and then reset the the cutter height and repeat the passes? Would you use a bit with a 3/4" diameter cut? I'm not trying to be a smart alec. I'd really like to know how you would process all of the wood for that project.


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## Scrit (24 Jun 2006)

Dave R":obhspkmk said:


> .....I'm curious as to how one might go about making something such as the grate I drew in Mark's Slatted Mat thread without using a dado set on a saw. This is a traditional way to make grates for boats.



The answer is that nowadays a smaller trade workshop would probably use a crosscut saw (much heavier than a radial arm saw) with a dado head or variable groover on it (we used to call them trenching heads), then rip down, whilst the bigger workshops would cut it on a CNC router and again rip down. Another way would be to use a recessor or overhead router with a compound table to do the grooving. All of these ways would give you a 19 x 19mm cut in one pass. Shoving long bits of timber across a table saw sideways on has not really been part of how we do things here in the UK to the same extent as few table saws in trade places had sliding tables and shoving a table or sled is much more physically demanding than pulling a crosscut over IMHO. Most of the established yards I've seen had a Dominion or Wadkin crosscut lurking somewhere set-up for just this task, frequently the had just one machine, a Dominion Elliott combination woodworker (alright I've only seen a few boat builders - but they seemed universally to own a hulking great crosscut). 







Above: Wadkin recessor with compound table
Below: Wadkin router (non-compound table version)











Above: Wadkin CD crosscut saw (sans bench - note the home position guard and lack of nose guard on the saw blade)
Below: a Dominion Elliott combination woodworker. Note the swivelling crosscut saw mounted on top











Scrit


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## SketchUp Guru (24 Jun 2006)

Scrit, that's all fine but what about the rest of us. Your methods are good but leave out the common hobbyist like me.


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## Scrit (24 Jun 2006)

Dave R":37i3rh0i said:


> Scrit, that's all fine but what about the rest of us. Your methods are good but leave out the common hobbyist like me.


OK, so I was trying to show what a boatyard might use, _mea culpa_  

The fact is, Dave, that in the UK RASs aren't that common, many table saws won't take a dado head (and my feelings about the lack of safety/guarding issues on this are well known.....) but many "Average UK Joes" DO have routers. So probably the best way to proceed _over here_ would be to square the end of the timbers and rout the grooves in 2 or 3 passes using a jig like this:






The stick rides against the edge or in the previous groove and the router is screwed to the top. A plane handle and knob could be screwed to the back and front respectively to ease use. By always registering on the previous groove and making the guide stick fit the slot precisely an accurate pattern of grooves could be cut.

Regards

Scrit


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## Paul Kierstead (24 Jun 2006)

Scrit":2r128kqd said:


>



Well, dang, you really do learn something new every day. That is damn cool, don't know why I never seen (or thought!) of that before.


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## Flyer (24 Jun 2006)

I have used dado blades here in Canada for at least 40 years, in school workshops too, and never experienced any problems. None of the equipment had automatic braking.
I use one on both my own table saw and radial arm saw and wouldn't be without a set.


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## MikeW (24 Jun 2006)

Flyer":q99rvum9 said:


> I have used dado blades here in Canada for at least 40 years, in school workshops too, and never experienced any problems. None of the equipment had automatic braking.
> I use one on both my own table saw and radial arm saw and wouldn't be without a set.


Not to pick on you, Flyer, but your post epitomzes our North American work practices and mindset--and this thread also illustrates the divergent mindsets and work practices of both traditions. Neither is inherently wrong. Just different. Both best practices accomplish the same goals and merely go about it differently. Ours does carry with it greater risk. Something which within our tradition is acceptable. But not within the UK and most likely other civilised countries outside the UK.

This discussion is really akin to a debate on religion. Neither point of view will convince the other. It will eventually stalemate--and probably already has.

Take care, Mike
off to count how many angels fit upon the head of a pin...


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## seaco (25 Jun 2006)

I have a Delta Unisaw and one of the reasons I bought it was that I could use a dado set, I find with careful thought to safety it is a wonderful tool for it's purpose.

Earlier posts say a router is quicker and easier to use well try cutting a 11.5mm wide trench 15mm deep in oak in one pass? I would need a hundred cutters to make up all the combinations of width I can do with my dado set...I know I can do multiple passes but that in itself adds more chance for injury

We all seem to have different reasons to be for or against dado's but in the end it's your own choice you won't suddenly be working in my workshop so if I'm happy to use one so be it, there will never be agreement on this so give it a few months and we will all be here again... :wink:

Lee


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## johnelliott (25 Jun 2006)

seaco":qlj1wzrw said:


> I would need a hundred cutters to make up all the combinations of width I can do with my dado set...I know I can do multiple passes but that in itself adds more chance for injury



Can't imagine how one would use a router in such a way that there is 'more chance for injury with multiple passes'?

John


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## seaco (25 Jun 2006)

johnelliott":3v3e237f said:


> seaco":3v3e237f said:
> 
> 
> > I would need a hundred cutters to make up all the combinations of width I can do with my dado set...I know I can do multiple passes but that in itself adds more chance for injury
> ...



Well simply because the router would be in use alot longer hence more chance of injury, it's not rocket science... I'm not saying the router is more or less dangerous than a dado but the longer a machine is switched on the more chance of something going wrong...


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## Scrit (25 Jun 2006)

seaco":37b974y9 said:


> Well simply because the router would be in use alot longer hence more chance of injury, it's not rocket science... I'm not saying the router is more or less dangerous than a dado but the longer a machine is switched on the more chance of something going wrong...


I don't entirely agree. Time of cut is not the safety issue, it's potential exposure to cutter which is. 



seaco":37b974y9 said:


> Earlier posts say a router is quicker and easier to use well try cutting a 11.5mm wide trench 15mm deep in oak in one pass? I would need a hundred cutters to make up all the combinations of width I can do with my dado set...I know I can do multiple passes but that in itself adds more chance for injury



The majority of housings people work are probably to accommodate the likes of shelves and rails, etc in sheet stock (18mm, 15mm and 12mm) and you can comfortably accommodate an 18mm wide x 9mm deep housing in a single pass with a 1/2in router. To adjust the cut it is probably simpler to add a rebate to the end of shelf, thus (BTW also true for dado heads):






This is a 16 x 9mm housing worked in 19mm stock (because the only cutter available is notionally 16mm) with a rebate in the top edge of the shelf. As the piece is to have a "face-frame" attached it doesn't matter what the end of the housing/shelf looks like - and I'd say that was true for most housed work. Better quality pieces would, in any case, be worked with a stopped housing or a different joint altogether. The jig to cut the housing looks like this:






The gap between the boards is 30mm to accommodate a 30mm O/D guide bush frequently supplied with a 1/2in router (the size normally used for kitchen worktop and stair housing jigs, etc), but there's no reason why a smaller guide bush couldn't be used. As the cut is made into the cross rail, this becomes a "register mark" for cutting the housings:






Total jig cost, circa £6 (nil if scrap used) - total cutter cost, circa £25 (for 12mm and 16mm) - total time to make, circa 15 minutes. set-up time is just your marking-out time really...... And because your hands are always above the cutter holding the router probably a heck of a lot safer that the dado head. Noise? Buy a Bosch or Mafell or Festool router and they are considerably quieter than the DW625 I use, but in reality the majority of the noise is made by the cutter on the timber in either case - so wear ear defenders.

There is also another fact to consider - that housings rob strength from chipboard, MFC and MDF and thus aren't suitable for use with those materials.

My experience of using stuff like trenching heads is that they can be a royal time-consuming pain to set to the right width and are only worth considering if you have a lot of identical cuts to make.

So, if not sheet materials what exactly do you use your dado head for?

Scrit


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## seaco (25 Jun 2006)

Hi Scrit

I use one of those jigs myself and very good it is, as I've already said we won't all agree on the best way to do this so we will all be here again soon... :wink: 

I think we will all have to agree to disagree...


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## johnelliott (25 Jun 2006)

seaco":13yfhh93 said:


> I think we will all have to agree to disagree...



Especially about this, from your previous post


seaco":13yfhh93 said:


> I'm not saying the router is more or less dangerous than a dado but the longer a machine is switched on the more chance of something going wrong......



I am saying that a router is_ less_ dangerous than a dado.

John


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## Scrit (25 Jun 2006)

johnelliott":39rthcv3 said:


> seaco":39rthcv3 said:
> 
> 
> > I'm not saying the router is more or less dangerous than a dado but the longer a machine is switched on the more chance of something going wrong......
> ...



Considering the above (the duration bit), I'm probably dead several times over! 8) - for that matter so are you, John!

Scrit


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## Alf (25 Jun 2006)

I'm inclined to think that if the dado head doesn't kill you, this thread might... :lol: 

I'm going to go and watch England stuff up against Ecuador now, for a little stress and danger of a different sort. Be kind to us poor football-watching saps when Ecuador go through, won't you? :roll: 

Cheers, Alf

Putting on The Lucky Shirt [-o<


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## seaco (25 Jun 2006)

I agree I'm getting so bored with this now...  

Simple if you don't want to use a dado don't buy one...


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## seaco (25 Jun 2006)

Alf":21tv03y1 said:


> Be kind to us poor football-watching saps when Ecuador go through, won't you? :roll:
> 
> Cheers, Alf
> 
> Putting on The Lucky Shirt [-o<



You were saying Alf, come on England....


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## Alf (25 Jun 2006)

It was the Shirt wot done it.  

Cheers, Alf

Happy to be proved wrong


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## Anonymous (26 Jun 2006)

seaco":1j9sxest said:


> johnelliott":1j9sxest said:
> 
> 
> > seaco":1j9sxest said:
> ...



Seaco, your argument makes no sense to me. Simply using a router for longer than a dado head cutter deos not make it less safe or the user more prone to injury.

At the end of the day, I still see no advantage in the dado head cutter over the router - and I used a dado for 2 years before reaching this conclusion. As for the argument made above about cutter sizes, how many sizes of dado do you reaaly cut? 1/4", 1/2", 3/4"? More?

Incidentally, I do not consider the dado head cutter any more dangerous than an unguarded tablesaw blade with no splitter (in fact I would say it is less dangerous!!)


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## seaco (26 Jun 2006)

Hi Tony

I'm not going into how useful or otherwise a dado is compared to a router we'll never agree, all I'm saying is a dado or router can only do you damage if it's rotating, my dado will do the cut I need in one pass the router would take more hence is rotating longer = more chance of injury...

Don't get me wrong I realise a dado set is a dangerous thing to behold but with proper attention to safety it's no more dangerous, any power tool will cause serious injury if handled improperly...

Everytime I use my dado set I realise it's potential for injury, so hence I take extra precautions for safety something that I may not do so much for the router...

Lee


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## Nick W (26 Jun 2006)

Oh puh-lease will one of you be man (person) enough to let someone else have the last word on this subject. Give it a rest - nothing new, _*or useful*_, has been said for the last n pages. Borrrrrrrrrring.


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## seaco (26 Jun 2006)

Nick W":2tlv0d3o said:


> Oh puh-lease will one of you be man (person) enough to let someone else have the last word on this subject. Give it a rest - nothing new, _*or useful*_, has been said for the last n pages. Borrrrrrrrrring.




I quite agree Nick I don't know why I keep being pulled back in but I promise that was my last post on this subject....


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## Colin C (26 Jun 2006)

Nick W":mqyyju30 said:


> Oh puh-lease will one of you be man (person) enough to let someone else have the last word on this subject. Give it a rest - nothing new, _*or useful*_, has been said for the last n pages. Borrrrrrrrrring.


 \/ 8-[


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## Taffy Turner (27 Jun 2006)

As a Mechanical Engineer with some experience of H+S and Risk Assessment, gained in the steel industry (*please* don't make me do that again!!!!), I think that we are all overlooking the most serious risk associated with dado cutters which is :- 

*The very real risk of dying of boredom whilst trawling through 12 page topics about them that re-hash what has been said in all the other umpteen page posts about them on this site!!!*     

At the end of the day, as a private individual, no-one is more responsible for your health and safety than you are. Look at the process, analyse the risk, and if you are happy to accept the risk, then go ahead. If you then have an accident, you have no-one else to blame but yourself. If you understand this premise at the start, it is surprising how it modifies your approach to so many things in life!

Regards 

Gary


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## Alf (27 Jun 2006)

Ha-hum?



Earlier (on page 11) Alf":v8ff40xn said:


> I'm inclined to think that if the dado head doesn't kill you, this thread might... :lol:



Cheers, Alf :wink:


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## Kane (27 Jun 2006)

Be worth stickying this thread as a "Dado Guidance" to make it easy for newbies to see. 

Yeah yeah I know search feature blah blah blah lol but if you have a sticky that shows the pro/conc/alternatives why not sticky it and avoid confusing novices with the less clear threads that exist


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## Adam (27 Jun 2006)

Kane":yiagq86m said:


> Be worth stickying this thread as a "Dado Guidance" to make it easy for newbies to see.
> 
> Yeah yeah I know search feature blah blah blah lol but if you have a sticky that shows the pro/conc/alternatives why not sticky it and avoid confusing novices with the less clear threads that exist



Sadly, that doesn't work. People still ask the question anyway. Also, dado threads are good for the winter months, helps keep your blood temperature up. :lol: 

Besides the forum wouldn't be fun it we didn't have at least one contentious issue. The forum rules steer away from politics and religion, so really, there is only dados left after that :wink: 

Adam


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## Kane (27 Jun 2006)

True and it helps get my post count up too lol


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## johnelliott (27 Jun 2006)

Taffy Turner":swaw5fzl said:


> At the end of the day, as a private individual, no-one is more responsible for your health and safety than you are. Look at the process, analyse the risk, and if you are happy to accept the risk, then go ahead.



That's very true. I will still reply to threads of this type not because I hope to dissuade 'dado blade in saw bench' users from doing so, *but to dissuade beginners from doing so.* I understand that many beginners watch an american woodwork programme which shows these devices being used, and beginners may quite reasonably think that there is nothing wrong with doing so, when of course the reverse is true

John


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## nonidentity (27 Jun 2006)

Besides adding to my count. I think the message is that perhaps as sticky thread can be posted presenting the arguments for and against dado head cutters.

Besides the new sawstop? table saw can reopen the potential because of the safety factor is built in the design. It seems that problems associated with the dado is due to the current design of table saws and perhaps new innovations may lead to new solutions.

Soemthing to think about? :roll:


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## Paul Kierstead (27 Jun 2006)

I think one of the curious things you see regarding safety is a focus the end result rather then how you get there. This is not quite Dado vrs Router (or at least I am avoiding that issue) You will often see "X is as safe as Y if they are both used correctly". This kind of approach really misses the point. By definition, they are all safe when used correctly; they only become unsafe when procedure fails. Now the question becomes, what is required to use it correctly? Lets say, at an extreme:

Machine X requires 1 simple step which, if not performed, will raise the chance of injury by 20%.

Machine Y requires 5 steps, which must be performed perfectly and in exact order or catastrophic failure results.

Now when used correctly, but are 'safe', but machine Y has a much much larger chance of not being used correctly, especially by the unitiated. The analysis of risk must also include what the chance of using it incorrectly is, not just the end result of correct usage. In addition, if there is an accident, one must consider the consequences of of the accident. For example, accidents frequently occur with chislels, but these very rarely require more then stitches and often just a bandaid. Accidents with chopsaws are much less frequent, but much more severe. Accidents with cement mixers (the kind at a cement plant...) tend to be fatal. So I think the simplistic view expressed largely in this thread doesn't even get close, on the whole, to the real risks; there is insufficient information here to make an informed choice. Now how one could get sufficient information, I am not sure; has anyone done a formal risk analysis on the Dado?


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## Alf (27 Jun 2006)

Adam":gnqgcsns said:


> Kane":gnqgcsns said:
> 
> 
> > Be worth stickying this thread as a "Dado Guidance" to make it easy for newbies to see.
> ...


But at least we could point them to the sticky with one simple link. And then lock the thread - quick. Mind you, it'd probably take a 50 page thread for everyone to decide what exactly the sticky should say... :-k

Cheers, Alf


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## Scrit (27 Jun 2006)

Paul Kierstead":yc06zr43 said:


> .....has anyone done a formal risk analysis on the Dado?


Yes - I required one as part of my ACOP assessment, i.e. a legal requirement in a trade shop, where I had to show ther was no safer suitable methodology - it wasn't easy. My assessment, however, was for the RAS.

Scrit


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## Noel (27 Jun 2006)

For those that are bored stupid with this thread please refrain from reading it. It's not hard to determine it's subject.
For those that find it of interest please continue to read and contribute. The vast majority of posts have been informative, constructive and interesting no matter which side of the fence each point of view emanates from.
We are, after all, on a forum where discussion, debate and information is the reason why we are all here.
Hopefully a thread will never be locked for the sole reason that some members find the subject matter boring. Dados are a common feature of this forum but as long as people feel the need to start a discussion and others want to become involved I see no harm. 12 pages and nearly 4,000 views in a couple or three days means something.
But, as I mentioned, if you find a subject boring (and there's plenty of other threads that are boring in the extreme) move on.


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## seaco (27 Jun 2006)

Sorry Nick I know I promised but I'm back... 

OK I'm going to realise defeat here I'm not stupid if it ever happened "God forbid" I would rather fall on a router table than a dado blade...

But I will say that with proper safety precautions either is as safe as they can be, but it is true what I've read here that I wouldn't really be to happy for a newbie woodworker to get their hands on a a dodo set... hadn't really thought of that!

I will still use mine as I am fairly safety Conscious and love their ease of use I will also use my router for similar jobs when appropriate...

Lee


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## Kane (28 Jun 2006)

Noel":1nck7vem said:


> For those that are bored stupid with this thread please refrain from reading it. It's not hard to determine it's subject.
> For those that find it of interest please continue to read and contribute. The vast majority of posts have been informative, constructive and interesting no matter which side of the fence each point of view emanates from.
> We are, after all, on a forum where discussion, debate and information is the reason why we are all here.
> Hopefully a thread will never be locked for the sole reason that some members find the subject matter boring. Dados are a common feature of this forum but as long as people feel the need to start a discussion and others want to become involved I see no harm. 12 pages and nearly 4,000 views in a couple or three days means something.
> But, as I mentioned, if you find a subject boring (and there's plenty of other threads that are boring in the extreme) move on.



Agreed 

(runs off to check his post count )


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## JPEC (28 Jun 2006)

Kane":1pihodr9 said:


> Noel":1pihodr9 said:
> 
> 
> > For those that are bored stupid with this thread please refrain from reading it. It's not hard to determine it's subject.
> ...



Hear hear Noel, being new to this forum lark i have found it interesting, informative and entertaining :lol: 

Kane, you have a long way to go to catch up with Alf!!


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## Alf (28 Jun 2006)

Noel":1lxa4r09 said:


> 12 pages and nearly 4,000 views in a couple or three days means something.


A lot of people are hoping for a fight...? :lol:

While I fully agree with the principle that if you're not interested, go elsewhere, I do struggle to see what has been achieved _on topic_ beyond the summing up of the main points on page one. I defend your right to argue the toss about it 'til you're all blue in the face, but "the vast majority of posts have been informative, constructive and interesting" it ain't.

Cheers, Alf

Making sure Kane gets no closer with his post count... :twisted:


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## johnelliott (28 Jun 2006)

Alf":myemr5f1 said:


> but "the vast majority of posts have been informative, constructive and interesting" it ain't.



We will have to agree to differ on that. My opinion is that "the vast majority of posts have been informative, constructive and interesting" it *is*.


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## Taffy Turner (28 Jun 2006)

Paul Kierstead":1h3y51l0 said:


> has anyone done a formal risk analysis on the Dado?


 
Well, presumably the HSE did, which is why they banned (I know there is some debate about this - but for the sake of simplicity lets just assume that they have) them in professional workshops in the first place. 

The principal underlying much of the current H+S legislation is that a process "shall be made safe as far as is reasonably practicable". What this boils down to is that if a high risk process is the ONLY way of achieving a given result, then you are OK to carry out that process (provided all reasonable steps have been taken to minimise the risk). 

The problem is that the issue of what is reasonable practicable tends only to be explored in court after someone has had a reportable accident. In the case of an accident involving a dado blade, I wouldn't fancy anyone's chances of successfully arguing that the use of the dado set was the only way of achieving a rebate. Hence their use is "dissuaded" by the means that we currently see. 

Having worked with a number of Factory Inspectors over the years, I have to say that most (there are exceptions) are reasonable people, with a sensible attitude. The reason that the HSE gets such a bad press isn't due to the Inspectors themselves, it is due to local authorities etc making ridiculously over-zealous rulings in order to protect themselves from being sued by the no-win-no-fee brigade. The unfortunate side effect of this is that it undermines the generally sterling work that the HSE do in order to try to make the workplace a safer place. 

Regards 

Gary


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## stuartpaul (28 Jun 2006)

Taffy Turner":3gv8rm17 said:


> The principal underlying much of the current H+S legislation is that a process "shall be made safe as far as is reasonably practicable". What this boils down to is that if a high risk process is the ONLY way of achieving a given result, then you are OK to carry out that process (provided all reasonable steps have been taken to minimise the risk).
> 
> The problem is that the issue of what is reasonable practicable tends only to be explored in court after someone has had a reportable accident. In the case of an accident involving a dado blade, I wouldn't fancy anyone's chances of successfully arguing that the use of the dado set was the only way of achieving a rebate. Hence their use is "dissuaded" by the means that we currently see.



Gary,

Without wishing to be a pedant that's not strictly true. So far as is reasonably practicable implies a judgement of risk versus cost. If the risk is disproportionate to the cost of eliminating or reducing then it *may *be acceptable to continue. If the risk is high (e.g. fatality or serious injury) then the employer would be expected to put a lot of effort into dealing with it or indeed not doing it at all.

Also don't forget that other 'legal standards' exist (practicable and absolute) which require greater effort to be put into risk reduction. The current machinery regulations are absolute (i.e. they must be followed, - no exceptions).

Stuart


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## Kane (28 Jun 2006)

Alf":36b30h83 said:


> Making sure Kane gets no closer with his post count... :twisted:



that's a bit harsh mate 

(Honest that's the last post count boosting post I'll make lol )


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## Woodythepecker (28 Jun 2006)

As i was painful reminded a little over a year ago:



> I wrote,
> 
> Having used various sorts of woodworking machines for a good few years now, i thought, at least safety wise, that i knew the score. Then yesterday i was taught a valuable lesson, that will not only see me off work for a few days, but is also very painful.
> 
> ...



we work in shops full of tools and machinery, where in one moment we can be seriously injured or worse killed, and this does not need to happen on anything that the HSE may or may not think is dangerous.

So what is dangerous about dado head cutters? IMHO they only become dangerous if the operator does not use them safely. 

If you want to use a dado head cutters, go ahead. Just treat them with the same respect you would any other sharp tool.

Regards

Woody


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## Taffy Turner (28 Jun 2006)

stuartpaul":6uaqwv8h said:


> Taffy Turner":6uaqwv8h said:
> 
> 
> > The principal underlying much of the current H+S legislation is that a process "shall be made safe as far as is reasonably practicable". What this boils down to is that if a high risk process is the ONLY way of achieving a given result, then you are OK to carry out that process (provided all reasonable steps have been taken to minimise the risk).
> ...



Stuart,

Fair comment. I was trying to keep my posting reasonably short (failed dismally there!). I was trying to avoid a lengthy discourse on H+S regulations. Having re-read my post, I agree that what I conveyed wasn't exactly what I meant to say.

Thank you for pointing that out.

Regards

Gary


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## johnelliott (28 Jun 2006)

Woodythepecker":j6redmbf said:


> If you want to use a dado head cutters, go ahead. Just treat them with the same respect you would any other sharp tool.



This is the bit that I have the problem with. I have no objection whatsoever to people using dado head cutters. What I have the problem with it those people telling _other people that it is OK to do so_, regardless of provisos that they add.

John


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## Scrit (28 Jun 2006)

Woodythepecker":kc4rr60p said:


> So what is dangerous about dado head cutters? IMHO they only become dangerous if the operator does not use them safely.


The danger in the main is the _manner_ in which they are used by default - with inadequate guarding - and there's the rub because that's exactly how Uncle Norm and others show them being used. The other major danger is inherrent in all non-limiter tooling, i.e. the extent of any injury being much greater in the event of a contact accident than if limiter tooling were in place. So, if you have an accident with a stacked dado set there is a greater liklihood of an amputation than an equivalent accident with limiter tooling.

The pity is that _some_ manufacturers, including Scheppach and Felder, have taken the bull by the horns and produced a safer solution - (expanding) chip limiter tooling which locks adequately to the arbor and is used in conjunction with saw which has an adjustable rip fence (to give the short rip fence) and an optional SUVA (overhead) guard. So the problem is solvable (bites tongue before slagging off importers various and sundry)

Scrit


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## orangetlh (29 Jun 2006)

I feel i want to give my opinion on this matter but i want to get sum facts straight first. Out of interest what do you actually want to use a dado head for? Is it soley trenching or do you have some other use for it. Also what kind of dado do you intend to use? Chip limited, saw blades or plain cutters an do you plan on using it for cross grain cutting or ripping?


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## Sawdust (29 Jun 2006)

orangetlh":531aktfx said:


> I feel i want to give my opinion on this matter but i want to get sum facts straight first. Out of interest what do you actually want to use a dado head for? Is it soley trenching or do you have some other use for it. Also what kind of dado do you intend to use? Chip limited, saw blades or plain cutters an do you plan on using it for cross grain cutting or ripping?



Initially on the radial arm for use cutting tennons. At the moment I use a standard cross-cut blade and make dozens of overlapping cuts. I would like to be able to do it quicker with the dado head.

I tried ripping on the radial arm a long time ago and it put me off for life so it's only ever used for cross-cutting. 

I don't have a table saw but as I've just moved house and now have a decent sized double garage, I'm thinking about getting one. If I do, its main use will be for cutting panels as I have a big bandsaw which I use for any ripping I need to do. I do like the idea of beng able to to cut dados in the panels and would construct a good overhead guard should I decide to use the dado for it.

As you can see, it's very much just at the ideas stage at the moment, which is why I started the thread off in the first place and I think it's been useful for me to find out what people think.

Not really sure about what type yet but any advice is gratefully received.

Thanks
Mike


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## Scrit (30 Jun 2006)

deWalt used to make a pair if split "semi-limiter" dado heads for their radial arm saws - an 8in cutter for the 10in saws and a 10in cutter for the 12in saws - 7.5 to 14.5mm and 13.0 to 25mm from memory (although I could be wrong). The width of cut is set by adding-in shims. These are no longer made and will really only work on non-braked saws as there is little spare arbor for a locknut on arbor with wider settings. However they do come up on eBay from time to time. To go with then deWalt also made a spring return mechanism (still available) and a wider dado guard (no longer made). 

So to make them (dado heads) useable more safely on an RAS you need a wider guard with an adjustable nose piece (see the HSE Info Sheet #36, page 2), a "home" guard (not a bad idea as you'll need a chip catcher behind the saw in any case), a spring or counterweight/pulley/weight return and that's all, unless your saw is braked in which case I don't know how safe it will be even if a locking nut is fitted as these heads are heavy and the momentum might even overwhelm the motor brake.

Of your RAS is something like a Charnwood/Inca or another lighter I'd suggest getting something a bit less flimsy first.

Scrit


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## Sawdust (30 Jun 2006)

Scrit":oh4p8a47 said:


> Of your RAS is something like a Charnwood/Inca or another lighter I'd suggest getting something a bit less flimsy first.
> 
> Scrit



My saw is an 8inch Ryobi (no longer made as far as I know), about 18 years old and is unbraked. The blade guard is wide enough to accomodate the cutter and I would add additional guarding and the return spring or counterweight. However your comment has got me wondering as it definitely isn't as heavy as a Dewalt and I don't really want to replace it.

Why is nothing ever simple?

Cheers
Mike


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## Scrit (30 Jun 2006)

For an 8in saw you'll need a 6in dado set/block. Was the Ryobi the machine with the high speed router arbor at one end of the motor? They are a bit lighter than the small deWalts but not really that much. 

The Charnwood/Inca/Eumenia/Zinken were all very similar (if not the same) and are pretty lightweight. The lighter they are the greater the tendency the arm has to flex and therefore the more likely you are to experience "self climb milling" where the cutter set attempts top climb the workpiece it's cutting. This happens with my DW from time to time (not often) and it just tends to judder a bit and sometimes stalls the motor - normally indicates that the cutter block needs a trip to the sharpener. So as long as the blade set is kept sharp and you feed smoothly you'll not experience many problems. 

The plus of a RAS with a dado head is that your hands should be well out of the way if you are using the machine properly and you're therefore less likely to experience problems. The blade is also easy to guard with just a wing nut, carraige bolt and a sliding wooden nose guard to add to the existing guard.

Scrit


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## orangetlh (30 Jun 2006)

personaly i dont see a problem with using a dado to cut trenches and tennons as long as its guarded. One thing i would never do is put a dado in a saw bench and do any kind of ripping, or even pass a piece of timber over with a sliding fence. I spent a few years working in a saw mill for a timber merchant and had to make loads of trenches for bespoke door linings. I never had a problem with using one but in knew my limits and i know how to treat timber on a RAD. Although with the new PUWER regulations about braking, me personally and also the company thought that it was too dangerous to run a dado on a braked saw, as there is a very real risk of the nut coming loose. At the end of the day i do things in my daily work that probably arnt ACOPs and would probably be concidered dangerous by many, but i know how machines and cutters work and what is going to happen if anything goes wrong. Its all down to personal choice as to wether you use one, as long as you know the dangers and put mesures in place to reduce them to the minimum. All i would say is never trench too deep in one hit, always take it in steps. Always make sure your piece of timber is solidly held against the fence along its whole length. Never try to trench a piece of twisted or bowed timber, and just i tip i used, just pull the saw out at an inch or so at a time and return it back, that way if the timber moves or tries to bind your always recutting it.


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## Sawdust (1 Jul 2006)

Scrit":rlqhtlqu said:


> Was the Ryobi the machine with the high speed router arbor at one end of the motor? They are a bit lighter than the small deWalts but not really that much.



Are there any machines that you don't know about :wink: 

Yes it's this one:

http://www.thelodge1.karoo.net/recreati ... erfing.jpg

I've used it as an overhead router a few times:

http://www.thelodge1.karoo.net/recreati ... arings.jpg

This was before I realised the importance of dust extraction, I just used to wait until it was knee deep and then shovel it out!

It's actually been a really good machine.

Mike


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