Dado cutters - Please, what is so dangerous about them

[Alf]

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:

 

[johnelliott]

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.

 

[Taffy Turner]

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

 

[stuartpaul]

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

 

[Kane]

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 )

 

[Woodythepecker]

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.

I was always told that when using a table saw, planer/thicknesser etc etc to stand to one side so that if there was a kickback i would not be standing in the way of a 200 mph timber missile that was trying to escape through the workshop wall. But yesterday while sizing up some spalted beech i was talking to SWMBO and not taking notice of what i was doing when all of a sudden some of the timber cut loose and tried to take a shortcut through my stomach . Luckily enough it only hit me in the side but i still needed 27 stitches.

So be careful out there and take notice of what you are doing ALL of the time because one lapsed of concentration could cost you dearly.

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

 

[Taffy Turner]

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

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

 

[johnelliott]

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

 

[Scrit]

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

 

[orangetlh]

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?

 

[Sawdust]

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

 

[Scrit]

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

 

[Sawdust]

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

 

[Scrit]

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

 

[orangetlh]

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.

 

[Sawdust]

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