David Marks choice of joinery

[Lazarus Long]

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.

[V.E. Dorn]

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

[Greg G.]

Marks loves his Multi-Router. 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:

Form your own conclusions.

Greg G.

[Doug Stowe]

It is a valid technique that I suspect he wanted to demonstrate on the program(you can't do every project in the same way or you will bore your audience) and it is easier than a regular mortise and tenon joint.

And then there is that old thing of doing something just because you want to.

[Greg G.]

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.

[Mike G]

One reason for a loose tenon, especially in projects in projects with lots of them, is the tenon's can be made of less expensive secondary wood.

[Andy Dingley]

You make it by cutting two mortices, not a mortice and tenon. If your workshop is tooled up to cut mortices (maybe a router and jig) then this is easier.

The tenon may be stronger timber.

M&T joints are weakest (if well designed) across the neck of the tenon. A long-grain joint along the sides of a loose tenon should be far stronger.

You can use the "beadlock" system with loose tenons, where the mortices are routed and left with their rounded corners. The matching loose tenons are commercial items, which is a clever marketing idea.

Long sliding dovetails are hard to make accurately, and they really do need a router. This might be a consideration for a wide-audience TV show.

I can't see Chinese joinery making good TV. It's complex to do, but it's hard to understand by looking at it (so much is hidden when assembled) and most of the skill to it is doing a simple task very, very well, rather than some exciting new gadget that you can easily demonstrate.

Always remember that the function of woodworking TV is to make TV, not to make furniture.

-- Congrats to STBL on his elevation from TLA to ETLA

[MattH]

Greg G. wrote in news: [e-mail]:

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

[Brian]

I've often wondered about Marks' choices of joinery too. I think what it comes down to is there is no "right" method and on his show he is demonstrating a variety of methods. It always irritates me when he uses that multi router, because, well, I wish I had one. :-)

As far as mortise and loose tenons, I like to think about them as "super" biscuits. And biscuit joinery itself, based on breakage testing, is incredibly strong.

I watched that bookcase episode too, and I agree that blind sliding dovetails would have worked also, but probably no better than his mortise and loose tenoning.

Brian.

[Brian]

Yeah, where ultimate strength is desired, pocket holes are the wrong choice indeed. They do, however, have their uses.

Brian.

[Swingman]

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.

[Greg G.]

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.

[jev]

But apparently, although integral

I use loose tenons a great deal for several reasons not least of which is I find it much faster than classic tenon joinery. I think one should be very careful about using a different material for the tenons than is used in the pieces being joined. This can lead to problems of unequal expansion/contraction characteristics thereby weakening joint over time.

[Eric Lund]

Then again, in this particular show, he did not use the multi-router. Instead, he did all the mortice and loose tenon work with a plunge router, something we can get at reasonable cost.

Cheers, Eric

[Brian]

Yes, exactly. That's how I do it.

Brian.

[Andy Dingley]

But what is a biscuit joint ? Multiple skinny tenons, or an edge-glued joint with alignment guides ?

-- Congrats to STBL on his elevation from TLA to ETLA

[Eric Lund]

Whether loose or integral, holding the static weight of books is not too great a challenge for either of these joints. Loose tenons are easier. You cut the stock to exactly the size of the shelf width. You don't have to worry about uneven shoulders because you only cut mortices.

A valid choice. I can cut mortices without power tools, but I don't have a convenient way to cut a sliding dovetail. I think I've seen a specialty hand plane for that, but it seems like a lot of work for little added benefit. The shelves I recently built for SWMBO, I used a blind dados. They don't appear to be falling apart.

Marks really like loose tenons. Guess that's reason enough. The purpose of joinery is to bind two boards together in a manner strong enough for the intended use. In this regard, he succeeds admirably.

Of course, in my opinion, those bookshelves are ugly. They look top heavy. I like a lot of his stuff, but my other gripe about his projects is often the colors just don't work for me. The colors often clash. Contrast is fine, but if the tones clash, the result is ugly. I recently finished some laminated bread knives, made as Christmas presents. In one combination, I used Padauk and Red Oak. The red tones of the Red Oak made it a good contrast to the red Padauk. I I had instead used White Oak, I believe the brown tones in the White Oak would have clashed with the Padauk.

Cheers, Eric

[charlie b]

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

[Bruce]

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.

[g]

It's not. The strength is the same. See the report on the PDF that someone already posted a link to.