# tenon size, length, ect...



## dribron (Jul 19, 2010)

Hey all
So I am begining to play with the idea of trying my hand at M&T. But was wondering something.. If I were to say attach a 1.5x1.5 leg to a 3.5" apron @ 3/4" thick. And cut the mortise 1/4" thick. Would I make my tenon 3 1/2" x 1/4" Or should I cut it down to say 1" x 1/4"? Also how deep should the tenon go into each leg that is 1 1/2" x 1 1/2"? I'm guessing around 1" might be okay, or is that too much?
Sorry for the odd questions, I am just not sure of such things just yet.

Thank you
_Duane


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## tymann09 (Mar 4, 2011)

Duane,
So there are a couple things to consider, one is if the top of the apron is to be flush with the top of the leg, a good rule of thumb is to begin the tenon at least a 1/2" down, this is because if it's closer to the top, the leg with the mortise will split at the top, (trust me i've done this mutiple times:thumbsup So typically what i would do in this case is make a tenon that is 2 1/2" x 1/4" x 1" deep. another thing to keep in mind with the depth of the tenon, usually try to go at least half of the thickness of the leg. in this case 1" is plenty sufficient. 
Hope this helps.


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## TGRANT (Jan 25, 2011)

Agree with Tymann09. A general rule for tenon thickness is about 1/3 the width of the apron. Depending on the thickness of the leg, you can go a little more. The key is to leave enough shoulder to prevent wracking. Since the strength of the joint is in part related to long grain to long grain surface area of the M&T contact, the deeper the mortise the better, with the caveat that you don’t go too deep so that you affect the leg. Another thing to consider is adding a haunch, that is the mortise should go all the way to the top of the leg, but for the top ½" or so it is only ¼ to 3/8" deep. This decreases the twisting motions where the tenon meets the mortise. With that said, I don’t always do that and have not had any problems, but you will see the haunch described in many publications.


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## dribron (Jul 19, 2010)

Thank you both so much for the input. I was going to go with the 1/3 rule, but just wasn't sure on the higth of the tenon. I was kinda thinking 2 1/2 on a 3 1/2 board should be okay, but just didn't know if there was a general rule to go by. I have the leg stock, and apron stock cut ton leanth, and should have time this weekend to make the mortises and tenon, or at least I hope. After the mortise is cut in the legs I am planning on tapering the legs. Then I have the drawer to build, and I am pretty much ready to finnish it up. 
Man o man is this stuff fun.....!


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## tymann09 (Mar 4, 2011)

not a problem at all. glad you're enjoying it.


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