David Marks choice of joinery

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.

Perhaps he did it to show viewers how to do a loose tennon. Why don't you drop him an e-mail and ask? I understand that he does reply to some of them. I think it is a good question.

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Originally Posted by John Piwaron

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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I've always been lead to believe that loose tenons (bad word...they really aren't "loose"...) have pretty much the same strength as traditional M&T. It comes down to glue area and grain direction. They also can be easier and faster to execute since you can quickly mill the mortises with a router and jig (or a fancy machine like David uses) and produce tenon stock quickly with the table saw and router table.

I used the "loose tenon" method on the base for our kitchen table, a three leg design that required a bunch of joinery where milling traditional tenons would not only have been more difficult, but due to grain direction, potentially weaker from a structural standpoint. (Not a glue joint problem) In the picture below, you can see the three joints that this method was used where the "tips" of the base just above the feet join the main body of the structure. Because that body is effectively a "triangle", there are three different grain directions to deal with in a place that takes the stress of a 200 lb teak table top.

John,
Jim Becker is correct. Loose tenon can actually be stronger if the tenon stock is made from a stronger wood than the body that is being joined. It is simpler to construct since the tenon is not carved from the part that is being joined. The shoulders if not perfect can leave a visible gap in the finished connection. I use both methods and have not had any structural joint failures with either. I do enjoy the traditional method and the additional demand for a clean well fitting joint that is a monolithic part of the stretcher or body.
Mark

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Originally Posted by Jim Becker

I've always been lead to believe that loose tenons (bad word...they really aren't "loose"...) have pretty much the same strength as traditional M&T. It comes down to glue area and grain direction.

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Yeah, o.k., I understand. Your application looks like an excellent example of a need for this method.

The bookcase I mentioned isn't one of them. Perhaps his choice was based on no more than being easy to do (I'll give it that) and the availability of a fancy machine. However, in this episode he didn't use the fancy machine but instead used some jigs with stop blocks along with an edge guide on a plunge router to cut the mortises on the ends of shelves and sides. He made a template to guide the plunge router to cut mortises on the flat surfaces. David does love templates.

Perhaps I just haven't built anything yet that needed the loose tenon method. Hopefully, life is long, I'll run across the need someday.

BTW, your table sounds beautiful. Any pics of the finished work?

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Originally Posted by John Piwaron

The bookcase I mentioned isn't one of them. Perhaps his choice was based on no more than being easy to do (I'll give it that) and the availability of a fancy machine. However, in this episode he didn't use the fancy machine but instead used some jigs with stop blocks along with an edge guide on a plunge router to cut the mortises on the ends of shelves and sides.

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The nice thing about woodworking is that there are always multiple methods to do something. David could have used traditional M&T, loose tenons, biscuits, sliding dovetails or probably several other methods to effectively build the project. (I did not see the episode as I don't get DIY). It could have been a coin flip that picked the method! But I guess the end result is what counts the most.

Regarding templates, I've been making them more and more myself, both to assist with a given project and to preserve the ability to build the same thing another time with less setup. The material for templates is usually cheap and making them is not a horrible habit to get into. My second project was the NYW Adirondack chairs and even then I made some 1/2" MDF templates to make future versions a lot faster to layout and produce.

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BTW, your table sounds beautiful. Any pics of the finished work?

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Sure, here's two pics of the finished table "in place". Of course, this is prior to the kitchen renovation, so the dark walls are still evident. There are six three-leg Nakashima Mira-style chairs partially completed to accompany it. (The brick floor is the reason for the three-leg designs) The table top is 2" thick teak and originally came from Viet Nam when my wife's parents (and the kids already born) lived in Thailand back in the 60s. It was in her mother's house leaning up against a wall when Ali settled the estate, so we brought it home. It was in really poor condition and split (not cleanly) down the only joint in the middle. The two pieces were too big and heavy to push across my jointer, so after I stripped the gunk off the sections, I made a temporary sled to "joint" the edges on the table saw so the top could be re-assembled. I then reassembled them and refinished the beautiful top with Watco oil and the evil poly as a top-coat. That top is only two pieces of wood and is 52" in diameter...actually, the two piece are from the same board, cut and folded back before the circle was cut. The bottom is still rough-sawn as I have no doubt the table was originally built purely with hand tools. The new base is made from mahogany and for some reason, came out the exact same color as the natural teak did.

John,
I have a new post that compares the use of both types of joints.
Mark