Dados! What are they good for?.. absolutely *******?

[johnelliott]

As to WHY you would cut a dado in cabinet construction, have you ever watched the New Yankee Workshop? Norm Abrams method of work is a great example of this.

No, I haven't seen any of those programmes, so I guess that leaves my question about why anyone would use dados in cabinet construction relatively unanswered.

As to comparisons safety wise between router and table saw, the router is MUCH safer due to the fact that the operator will have both hands on the handles of the router whilst performing the cut. If the hands are there then they can't be anywhere else. Also, the forces exerted on the material by the router are different, there is no tendency for the material to be flung back at the operator.

John

 

[Philly]

John,
Do you actually use a router? Do you have one mounted in a table? (obviously, in a table that would be the same as using a table saw.........)
I have suffered some vicious kickback using a router-you hit a knot and sometimes you REALLY know it!

As to why you would use a method of construction, i.e. dado, M+T, dowel, I'm sure you must have some basic woodworking books? If not could I recommend the "Collins Woodworking Manual", it explains pretty much all standard methods of construction. And I really recommend, as a woodworker, that you catch an episode of "The New Yankee Workshop". You'll thank me for that, I promise!
best regards
Philly

 

[johnelliott]

John,
Do you actually use a router? Do you have one mounted in a table? (obviously, in a table that would be the same as using a table saw.........)
I have suffered some vicious kickback using a router-you hit a knot and sometimes you REALLY know it!

As to why you would use a method of construction, i.e. dado, M+T, dowel, I'm sure you must have some basic woodworking books? If not could I recommend the "Collins Woodworking Manual", it explains pretty much all standard methods of construction. And I really recommend, as a woodworker, that you catch an episode of "The New Yankee Workshop". You'll thank me for that, I promise!
best regards
Philly

Philly, why are you being so rude?. Do you think putting the smileys in your post makes it OK to be insulting? I'm going to resist the temptation to reply in kind, for the time being at least
John

 

[devonwoody]

Firstly may I also welcome Frank . Bet its cold there at the moment.

I cut Dadoes with my overhead Triton workcentre.The router can be set up on a plate that glides over the workpiece. Do not confuse this operation with the normal type of router table.

Also Perform have an adjustable rebate router cutter bit if cutting rebates at the edge of a timber piece. I have not yet worked out if it can be used without a table. Perhaps someone would give a definite answer to that one.

 

[johnelliott]

Also Perform have an adjustable rebate router cutter bit if cutting rebates at the edge of a timber piece. I have not yet worked out if it can be used without a table. Perhaps someone would give a definite answer to that one.

Using a router to cut a rebate on the edge of a panel, or even a trench, slot, groove, dado whatever, I always prefer to have the router resting on the material. This method gives a consistent depth, whereas using a router in a table, if the material is slightly curved, as most sheet material is, it either has to be pushed down onto the table, or the depth of the cut will vary. Pushing the material down onto the table is difficult with a large panel
John

 

[Keith Smith]

Accidents happen so easily and when we least expect them, you don't need to be a fool to have an accident, but it can help .

This week I was planing the edge of some pieces of hardwood on the planer, someone walked into the workshop, I looked up and with cold hands I dropped the wood onto the revolving cutters. Fortunately the guard stopped it completely coming into contact with the cutters but the wood still lept up and hit me on the hand (across the nails) with such force that they all started bleeding; looked pretty bad at the time but I was lucky and no lasting damage.

I have been putting the job off but I am insulating the workshop next week.

You can't rule out having an accident all you can do is minimise the risks, then when you do make a mistake it will be hopefully not too drastic.

Keith

 

[Philly]

John,
So what exactly are you asking?
I'm not trying to be rude. Are you asking "Why would you use a dado joint"? Here is a link to a practical use. It is the side panels of a chest of drawers, the dado's are for the dividing panels.
http://www.philsville.co.uk/images/drawers1.jpg
Can you see why the dado is useful for carcass work? It gives physical strength and location for the joint, as well as better glue surface area.
I wasn't being rude about the book recomendation or suggesting that you watch Norm's show. He uses dado's a lot in his cabinetry.
So I hope this helps answer your question.
Mind you, if you are asking "why would you use a dado in a tablesaw", you are welcome anytime to come on by my workshop-you can see one in use and try it out yourself.
This is a serious offer, not a mickey take!
Hope you didn't misunderstand me,
Philly

 

[johnelliott]

Philly, I am not asking you why anyone else would use dados in their cabinet work, I am asking you. I realise Norm is a hero of yours, but to me the fact that he uses dados means nothing. Unlike you I am a full time woodworker and much of my work is in cabinets. I do not find it necessary to use dados to hold my cabinets together, nor do I need dividers between my drawers.
Maybe you do need dados, if so, tell me why, don't say you do it because Norm does it, or because it says so in such and such book. If you are unable to answer the question then that's quite ok, I don't mind a bit.

Let me give you an example of a satisfactory answer--"I use dados because I work in what I feel is the classic tradition, and that tradition calls for shelves, dividers etc to be housed in dados in the cabinet sides"
Now let me give you an example of an unsatisfactory answer "I do it because Norm does it"

I suppose I should say that, as I make my living from woodwork, I have a different perspective from the amateur. I see no point in making any of my joints stronger than they already are, which is quite strong enough.
John
PS yes, I have used a router, but for reasons mentioned earlier, I would not try to cut dados with a table router. In fact, it wouldn't occur to me to attempt it even if the variable depth was not a problem

 

[Sgian Dubh]

Tony, You rightly deplore peoples lack of safe dado blade use, and give an example or two of safety steps that can be taken appropriate to grooving along the grain in narrow stock or grooves parallel to a long edge in long narrow panels.

Here's an opportunity for you to describe suitable guarding and safe use in another scenario.

It's a typical dado blade operation commonly done in cabinet and shelving construction. You're cutting an 18 mm wide housing (dado) to fix a shelf across the width of a bookcase end panel which is 2.4 metres long X 400 mm wide, and your housing (dado) is at a point approximately 1200 mm from one end. You're using a table saw fitted with the dado blade. Let's say You don't have a sliding table on your saw to the left of the blade, and even if you did have one of these sliding table saws in the UK the arbor will be (by government regulation) too short to accept a dado blade. You also more than likely have a European style adjustable rip fence because this is Europe and US style fixed long fences such as the popular Biesemeyer do not meet EC regulations and are not sold in the UK. You also probably have a small crosscut guide of some sort that runs in something like a T slot milled in the cast iron top of your saw.

With the above set-up and required housing or dado how would you provide adequate guarding such as the feather boards and hold downs you mentioned earlier when making these cuts?

You didn't address or counter my point regarding the cause of kickback, it being the result most commonly of the rear emerging up-cutting teeth of the blade engaging with the wood. Do you consider this an insignificant factor in dado blade operation?

What do you think is the most likely result if the piece of wood being worked twists on the saw table resulting in those all important rear teeth engaging with the workpiece? There is no riving knife to lessen the chance of this happening after all.

What happens if the wood pinches on the blade after the cut due to stress release such as might happen in case hardened material?

It's my experience that even with all the guards in place the 5- 12 horse power machines that I'm most familiar with will chuck heavy wood and man made boards pretty much wherever they darn well want if things get out of control whether through operator error or because of unforseeable mishap or accident. Material really can be kicked back in normal sawing operations where the riving knife and crown guard are in place-- it's happened to me. That being the case there's no real reason I can think of to describe typical unguarded dado blade usages as anything like high medium, medium or low risk. Slainte.

 

[Sgian Dubh]

Well to answer your original question John, housings are quite a common joint in carcase work.

They're used to locate shelves, horizontal dividers and other items like the horizontal framed runners and kickers in drawer work.

Whether the housing is worked at the full thickness of the mating member is up to the designer and also down to the maker.

A common alternative to a full housing is to cut one about 1/3 to 1/2 the thickness of the piece going into it and working a tongue on the edge or end of the mating part. E.g., an 18 mm thick shelf into a cabinet side where a 6, 9, or even a 12 mm housing is routed in the side using the diameter of the bit to determine the housing width, and a matching tongue is routed on the shelf end. This is a stronger and more positive joint than a full housing anyway because of the additional returns and shoulder lines it provides. Slainte.

 

[Noel]

"You also more than likely have a European style adjustable rip fence because this is Europe and US style fixed long fences such as the popular Biesemeyer do not meet EC regulations and are not sold in the UK"

Not the case, options available are Bies type (ie long, sometimes attached both sides of the table), short type or combo.

Noel

 

[Aragorn]

Hi John

I sometimes use housing joints. Usually the situation is when I need accurate location of the boards, good strength, no mechanical fastening (for aesthetic reasons) and the ability to make allowances for movement in the boards.

For example, on a bookcase, I use a housing joint top, bottom and middle. The other shelves would be adjustable (I use shelving pegs in holes routed along the sides).

The fixed central shelf is used to stop the sides from bowing out. I would use a housing joint here if I don't want to see any mechanical fixings (which is most of the time).

I haven't really come up with any alternative that fulfils my requirements that doesn't involve more time consuming joinery. For example, I could use M&Ts or even through M&Ts and make a feature of it on the outside of the bookcase.

Butt joints are rarely an option for me however they are fixed - plugged screws in through the sides are sometimes satisfactory depending on the finished quality of the piece. Pocket screw joints are never acceptable except where there is no possibilty of seeing the pocket (e.g. kitchen cabinet construction). I am not particularly tempted by the Miller system at the moment.

I hope this answers the spirit of your question as it applies to my style of woodworking.

Application-wise - I use a router if I have a small number of housings to cut. I use the Dewalt groove cutter blades in the Kity 619 for larger numbers of housings and for almost all grooves. The range of cut is around 5mm - 14mm in my saw, but the blades can cut up to 19mm+ in the RAS.

 

[frank]

can i just apologise it was me who started all this about dado' cutters .
i went to look at some saws and said that they would take a dado cutter , and that the firm selling the saws also sold the dado cutters .
its true you can hurt yourself with them as with a hand saw (how many of you have never cut yourself with one ) or any other tools what are thumbs for when using a hammer .

frank . who still hopes to get one of them saws .

 

[Midnight]

For me, dados are a no brainer; I'll use them any time I do carcass construction. As both Sgian and Aragorn have pointed out, there's nothing to touch 'em for strength and reliability. Personally I hate the look of adjustable shelving, and to date I haven't seen an adjustable system that I felt comfortable putting faith in; I prefer to progressively change the pitch between centres of my shelves instead..

As for how to make then... for me, I'm limited to using a router, or taking multiple passed over the table saw with a standard blade. To my mind, that multi pass mess is for the birds... way too damn slow, and it leaves the bottom of the trench looking like a ploughed field..

To date, the best two methods I've found have been to use a Pat Warner style set up (without his beam) to do cross cut work, or to use my router table, c/w auxiliary fence and feather boards.

Over the years, I've seen just about every way for a job to go to rats using a router set-up... guides drifting, depth stops failing, carbide tips failing and kick back that near tore the machine from my hands to name but a few; believe me it's far from idea... But as I've frequently pointed out before, I've no viable alternative as my saw isn't dado capable; probably its only designed in safety feature, nor is my shop big enough to let me trade up to a dado capable machine..

That said, given the frustrations with a router based set up, if I had a machine capable of using a stack head cutter, I'd be more than willing to use it as often as it was safe to do so; Sgian has pointed out the near suicidal risks associated with cross cutting long narrow stock; Pat Warners' system still wins there for safety and speed. For long ripping cuts however, a dado blade is unequaled, provided that proper Shaw guards (see HSE Woodworking Sheet # 16, Circular Saws - Safe Working Practices), or a power feeder is used, either ensuring that should the unforseen happen, that there's no way that the stock is coming back to bite you..!!
Shaw guards aren't rocket science, and power feeders are a fraction of the cost of a decent spec saw; to me it seems like tempting fate to use the blade in the absence of the safety gear... I've been bit too often to take any more stupid chances.

 

[Losos]

Frank D - Welcome to UKW - Would you like to put up your Canadian site? My French is not good but I'd like to visit sometimes.

 

[Anonymous]

Don't they make it a bit difficult to adjust the shelves?

John

John I hate to see adjustable shelving and agree with Mike - usually looks like MFI or B&Q furniture

Your choice of fixing is screw and glue
Are shelves that are screwed in place easy to move then?

John, it seems to me that you have made up your mind that dados are not needed. OK, then don't use them

I don't use screws and nails because I personally prefer traditional joints

 

[Anonymous]

Got to take a lot of issue with you on this one, Tony. There is another reason why accidents happen, not just stupidity. Other stuff happens too. Safety features aren't there just to protect stupid people, they are also there for when the unexpected happens, or when people faint or become dizzy or have blackouts for some reason that was completely unpredictable.
John

John, I think that you are being just a little pedantic here. Surely you must agree that most injuries are caused by incorrect use of equipment and not feinting etc.?

I think my point was and is valid. If the dado head cutter is used corectly and treated with respect it is no more dangerous that a table saw or router

 

[Frank D.]

Hi Everyone,
I don't have a 5HP saw (mine's 3HP) and haven't cut thousands of dados, but with a crosscut sled any risk of kickback on cabinet sides is almost reduced to nil. The sled has two runners in the miter slots and a rear fence which, combined with the mass of the sled and a clamp to hold the work down, makes it very difficult for things to go wrong. I don't know if you are familiar with such sleds, it sounds like you have a lot of regulations dictating tool and machine design.
As far as I know the only joint stronger for case dividers is the sliding dovetail. I'm not totally sure about this, though, and welcome any corrections.
Thanks for the warm welcome. For those interested, here's the French-language site that I spend too much time on: www.lamortaise.com .
Frank Desaulniers

 

[Anonymous]

It's a typical dado blade operation commonly done in cabinet and shelving construction. You're cutting an 18 mm wide housing (dado) to fix a shelf across the width of a bookcase end panel which is 2.4 metres long X 400 mm wide,



.

Sgian

I'm afraid to say that your hypothetical cut is nonsense.
Only a complete fool would try to cut a dado across a 2.4m board on a tablesaw. This was my point, stupidity is the main cause of injury from dado head cutters.

Suggesting ridiculous examples such as this does not prove a case against the use of dado head cutters as no one in their right mind would consider this a suitable tool for the job as described. I would use a router and straightedge.

If dado head cutters are USED CORRECTLY and for suitable jobs, then they are no more dangerous than a tablesaw or router

You didn't address or counter my point regarding the cause of kickback, it being the result most commonly of the rear emerging up-cutting teeth of the blade engaging with the wood. Do you consider this an insignificant factor in dado blade operation?

Yes I consider it an insignificant factor.

A dado cut is likely to be 10mm deep or less, thus the chances of kickback are almost negligible UNLESS the board twists because the operator did not support it correctly.

Kickback occurs when the upwards motion of the rear teeth grab and lift the board as they pass through it. The teeth hold the board as they rise up and accelerate the board upwards and towards the infeed side of the saw.
A dado cutter barely protrudes above the saw bed and does not cut through the board, and thus is very unlikely to grab the board and will certainly not be able to lift and accelerate and throw it with anything like the force of a normal sawblade. Basic physics.

Therefore, the dado head cutter is safer than a normal saw blade in a table saw without splitter (as most americans’ on TV and in mags seem to use it)

Finally, I am not disputing your point that dado head cutters may indeed pose a risk, but then so do all other power tools (especially when not used correctly)

 

[Midnight]

I don't know if you are familiar with such sleds, it sounds like you have a lot of regulations dictating tool and machine design.

Hi Frank... welcome aboard... if ya haven't noticed already, ya don't have to be nuts to post here.... but by God it helps.. :wink:

I know this sounds like sour grapes, but I did briefly consider a cross cut sled when writing my post above, dismissing it as utterly impractical in my narrow shop.... That said, in a situation where width isn't a factor, and provided the overhanging stock could be properly supported, I don't see why it shouldn't work...

Mind you... maybe I shouldn't say such things; cross cut sleds or dado blades on their own cause enough grief around here... but both together..???????

<shrugs...

doesn't mean it can't work though...