David Marks choice of joinery

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I was just looking at the Wood Works episode on the bookcase he built where the two sides have a bit of a serpentine curve to them.
In that ep, he joined the shelves as well as the top and bottom with mortise and loose tenon joinery.
First, if you're going to use M&T, why use a loose tenon? It seems that making and integral tenon in the appropriate place would be stronger.
Second, my own choice would be sliding dovetails. Blind of course.
So what do you think? There must be a reason for doing one over the other, what might that be? Normally he's all over a project with some incredibily complicated method. I'm waiting for him to introduce some chinese joinery into his stuff.
BTW, this isn't to knock anyone's methods, it's a matter of being interested in the "why" of it.
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Someone posted an article the other day regarding the degree of pressure needed to break different joints. The results were surprising to me in that two and three biscuit joints were very strong and didn't even break at the joint itself. It also surprised me that the loose tennon actually outperformed the traditional M&T. However, both of those ranked very high - I don't remember reading about sliding dovetails.
Don

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FWW published a study of joint strength that came to the opposite conclusion. M&T was the strongest, loose tenon, and double biscuits was last. Many of the biscuits sheared along the grain line.
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Ross
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On Sat, 3 Jan 2004 12:55:45 -0600, "My Old Tools"

What issue was that - I can't find it in their Index andwould to review it.
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In rec.woodworking

As would I. I imagine they pulled the joints apart in tension rather than pressing them apart the way this test did.
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The test was in the April 2001 FWW #148. The joints were not pulled apart. M&T tested to be more than twice as strong as double #20 biscuits. The loose tenons were closer. It does not attempt to say whether a joint is 'strong enough' for a particular application.
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Ross
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In rec.woodworking

Thanks for the useless information. How bout telling us what they DID do to the joints?

I'll bet it was in direct shear.
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Actually, it was racking like that experienced by a table leg or chair joint. You could read the article if you're really interested instead of attacking the messenger.
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Ross
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In rec.woodworking

I'm interested but I have no way of reading the article or I would. Only the table of contents is available online. As for the so-called attack, do you think you provided useful information in your first post?
Now "racking" is good information.

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He gave you very useful information: He told you where to find the test. Now why don't you, instead of bitching about MOT not doing your homework for you?
Cheers,
Kevin
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Lazarus Long said:

Marks loves his Multi-Router. <g> But apparently, although integral tenons are more conventional, loose tenon joinery allows choosing a material for the loose tenon that is stronger than the base material allowing for greater strength than an integral tenon.
Here is an interesting report you might look over:
http://www.netexperts.cc/~lambertm/Wood/biscuit.pdf
FWIW, Form your own conclusions.
Greg G.
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Greg G. said:

P.S. - I found the absence of pocket screw joinery techniques an interesting omission in this report, however. I would like to have seen a head-to-head test that included this 'new' joinery method - although I *really* hate those big holes in the backs of the stiles.
The results of both the dowel and lag screw techniques leads me to the conclusion that pocket screws are not all they are cracked up to be...
JMHO,
Greg G.
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Greg G. wrote in

A couple thoughts on pocket hole: 1) It isn't typically used where the screw threads go into end grain, as was the case with the lag bolts in this experiment. You'd only do that if you were joining two boards end to end.
2) Pocket holes are mostly used in joints that don't get a lot of sheer stress. Face frames for cabinets aren't stressed very much. Cabinet carcasses themselves have compressive stress on the vertical side plywood, but this doesn't affect the joinery. In my experience, cabinet joinery failures only seem possible during construction. Once everything is in place the joinery isn't stressed. This wouldn't be the case with a joint on something like a door, but then you wouldn't use pocket hole screws on a door. Just IMO... Matt
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Yeah, where ultimate strength is desired, pocket holes are the wrong choice indeed. They do, however, have their uses.
Brian.
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Brian said:

A few of the most favorable traits of pocket screws is that they are fast and self-clamping. They really do make for a tight joint - albeit a weaker one...
Greg G.
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<Greg G.> wrote in message

Like any other flavor of joinery, it depends upon the application. When it comes to face frames for cabinets, few other joinery methods rival pocket hole joinery for speed, appropriate strength for the job, ease of assembly without clamping and waiting for glue to dry, ability for self squaring with properly cut parts, and immediate use of the assembly.
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Greg, G. wrote: snip

A lag bolt has the threads going into end grain while the pocket hole screw has the threads in edge grain. The flat bottomed pocket hole and the flat bottom on the screw spread the force on the end grain over a much larger surface area than just the thread edges on the lag bolt.
As for why use pocket hole screws when there are so many other methods of holding two pieces of wood together - well, they are far more reversible than most other joining methods. That can mean a little bit more flexability when you're doing a piece that evolves as you go - something I seem to do often.
Regarding sliding dovetails - they can do what a mortise and tenon do PLUS they can pull and hold parts together WITHOUT glue thus allowing for expansion and contraction.
The big advantage of loose tenons is that if you blow making the loose tenon you're out some time and a few inches of wood. Blow a "fixed" tenon and you're out the whole part and the part is seldom just a few inches long.
Now about his choice of joinery being a function of the tools and equiptment he has available - "I'll do it this way just because I can" gives rise to a bigger question. Joinery use to be a way for a craftsman (generic term intended to denote humans in general and not just the male version of humans) to show off his hard earned skills, in addition to being functional. But with all the semi-no brainer machines, jigs and special fixtures available, anyone with a deep pocket and marginal eye/hand coordination can make what had been difficult joints. Does that fact diminish the importance and value of the true craftsman?
Michael Fortune discribed this dilema. You can design a piece and then figure out how best to make it, OR you can design things based on production methods available. He feels that the former results in a far greater range of design options and perhaps better pieces. What do you think?
charlie b
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In rec.woodworking

In some ways it does but I have to tell you, craftsmanship is still required, even with all the stuff available. A true craftsman will get a better result than a hack but most people will not know the difference. I'm talking about fit and finish.
I never cease to be disappointed at the lousy craftsmanship I see everywhere. My W and I were out at a restaurant last night and the booth had a plywood back that was coped to fit over some moulding on the wall. Not only was the coping PATHETIC with gaps exceeding 1/4", but there we still marks on the wood. It looked like he had used a Sharpie to mark with.

I always do #1.
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Bruce wrote:

About a month ago my future brother in law (wife's side) asked for help building a bar. I show up and he's got a frame built for it. He had fastened 4x4s to the floor at random distances, twisted 2x4s screwed and glued across at the top, more 2x4s edge glued and screwed for overhangs, more. I took one look and felt mind screwed and nauseous. Nothing level, boards waving at me. I gave him some suggestions (which was all I could do) and got out of there. I'm getting a headache thinking about it.
Went to their (lives with sis in law) place for the Christmas Eve party, bar looked fine. He took a few of my suggestions.
Apparently Future B in law was talking shit because wife's brother starts busting my balls about being too anal and how I like things done just so. Is this is a bad thing?
Then wife's brother starts some jag about me building cabinets and asks why I didn't just get Kraftmaid? I say because their junk. He goes off on another rant how Kraftmaids quality stuff. And on and on ......*
Which brings me to what Bruce wrote: People don't know the difference, they don't care to know the difference. If it looks pretty it's fine with them.
* This would explain my being an asshole the days around Christmas. A night with these people and I'm ready for homicide.
--
Mark

N.E. Ohio
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In rec.woodworking

I feel your pain Mark. They don't even know what to look for.
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