What size Tenons

Re: What size Tenons

Tony - Memphis

>I think 3/8" would be ok. I usually go 5/16" or so, but its not terribly critical. With all of the glue area on the tenon cheeks, there probably isn't a lot of stress on the shoulders. There are some rules of thumb. I must confess, I use a router for my mortises, so I use whatever bit "looks" right!

Tony

Re: What size Tenons

Sam Simpson

>Hi Y'all,

Gil, when sizing tenons always consider the other part of the joint. The mortice. In your current project you have a flush face where the rail meets the leg. You must be conscious of not making that face too thin at the mortise. One consideration might be to put all of the shoulder on the face side of the tenon. Personally I would offset the tenon and have a small shoulder on the back side. As for the thickness? 3/8 will work just fine.

Regards Sam Simpson.

A trick for you

Ellis Walentine

>The leg and apron joint is a high-stress joint but it is not like a frame joint, where the rails and stiles are all the same thickness. Usually, the leg is quite a bit wider than the apron rails, so you have plenty of room to increase the size of your tenon.

By this logic, you could increase your tenon size to 1/2" thickness, and still have 1/8" shoulders inside and out.

This is how I would do it in a typical situation. It would give you the benefit of the greatest strength and would not affect the integrity of the leg.

On more delicate pieces where you might have to play with the proportions to get the right joint geometry, I often offset my tenon to the inside of the rail, to gain strength in the outside tissues of the leg.

Remember, in a table joint, you're designing for the eventuality of Aunt Maude careening into the table accidentally, and those joints and shoulders had better hold up under the torture load.

At least that is one of the things I think about.

Ellis

Re: A trick for you

Gil

>Since my apron meets flush with the outside of the leg that would only leave me with 1/8" of meat in the front portion of the leg. That probably wouldn't support Aunt Edna too well would it? Hmm so many options so little time before Santa comes down the chimney with his Lacquer can and gun...

-Gil

Re: A trick for you

Moses Yoder in White Pigeon, MI

>If you haven't surfaced your lumber already and are using 4/4 lumber, try to leave it as thick as possible, which would be more than 3/4". Then, as Mr. Simpson and Mr. Wallentine both suggested the advantage of offsetting the tenon towards the back to leave more material at the front of the leg. I think 3/8" is plenty strong enough for a nice wide tenon that is well fitted; it would take a real catastrophe to break it.

Re: What size Tenons

Steve Wargo

>I was told that the rule of thumb is equal thirds for tenons. If the stock is 3/4" thick then each shoulder should be 1/4" and the tenon should be 1/4". This was an issue that I discussed with a fine cabinetmaker a while ago. The shoulders are just as important as the tenon. I was often making my shoulders 1/8" or a touch wider and that was where I was critisized.

Not in my book

Ellis Walentine

>Rules of thumb are just that, but I have a different take on joint design. Each joint has an optimal configuration, and the stronger the tenon, the better. In a leg/apron joint, as I mentioned above, you always have room to increase the thickness of the tenon, whether by making a centered recessed tenon thicker or by offsetting a tenon further into the width of the leg.

Your friend's advice about the shoulders being important is true, but I don't interpret it as meaning that they should be equal in size to the tenon. The role of the shoulder is to simply engage the surface of the mortise member, whether it is a stile or a leg. The width isn't important. The important thing is that it is there, acting as a fulcrum to prevent a racking force from defeating the cross-grain glue line between the mortise and the tenon.

Ellis Walentine, Host

Re: A trick for you

Alan Hamilton

>Ellis,

You leave my Aunt Maude out of this! I really had an Aunt Maude. You too?

Alan

Re: What size Tenons

Alan Hamilton

>Gil,

Simplicity for a simple mind--like mine!

I've always gone with the old, time-tested rule: less than a half, more than a third. I've forgotten where I first became acquainted with this old saw, perhaps Saint Roy of Underhill? Anyway, I use it and nothing else to size my joints. It's always worked out just right; I've had no troubles.

Such a rule, for my simple mind at least, means I don't have to futz around with any additional considerations. Going through all the mental gymnastic exercises, just so I could change a dimension by a whole 1/16" or so, would quickly drive me quite mad (though it would be a short trip).

Alan