Question about Tenons and mortise cheeks

[Chris Ryan]

I’m building a table. The aprons are flush with the sides of the leg. The aprons are roughly 7/8” and the legs are 2 3/4. My question is this:
1: do I stick to the 1/3 rule, which leaves me with 1/4” tenon and cheeks?
2: or do I make the tenon 3/8” and split the balance between the two mortise walls?
3: use an offset tenon with no cheek on the interior of the table?
Really concerned about blowing out the wall of the leg or using a tenon that’s too thin.
Thanks for your community wisdom!
Chris

[Edward Weber]

you say you have 7/8"
that would give you an extra 1/8" using your 1/3 rule
You can make the apron tenon 1/8" thicker (3/8") if you want and still have 1/4" cheeks.
There are many ways to divide up the 7/8" stock you're starting with. if all depends on what your piece requires most.

[Kevin Jenness]

You needn't fear blowing out the mortise wall with a 1/4" cheek any more than you would in a 3/4" thick stile. Either a 3/8" or 1/2" tenon will allow for a shoulder on both faces. I don't care for bare-faced tenons as there is no shoulder to establish a square glue-up. The thinner and closer to the outside leg face, the longer the tenons can be. With that size leg you won't have any problem fitting an adequate tenon. 1/4" is too light for a table of any real size for my taste.

[Ron Citerone]

I agree with Kevin. !/4" seems light for a table. I just cut 24 mortise and tenons of 1/4" for a jewelry armoire and while I feel fine with the size for this project, I would want more for a table. I am not a "Mortise Master" just my opinion though.

[Lee Schierer]

I think what Chris is asking is, what standard size bit should be use for the mortise. One third of 7/8 would be 9/64 which is not a common bit size. He would need to use 1/4" and then do a lot of hand work with a chisel to get to the 9/64". Or should he go to 3/8". Personally I would go to 3/8" and reduce the hand work on the mortise. I would center the tenon on the skirt and leave an 1/8" offset for the shoulder on the legs.

[Kent A Bathurst]

Hello, Chris:

The others above me are smarter than I. But...

I've ever gotten hung up on the 1/3 thing. If it makes measurement and joinery easier, fine. If not, fine. On your example, I'd go for 3/8"

However - I've also never gotten hung up on "tenon is centered in the rail". In your case, since you want the rail coplanar with the leg face[s], you might want and easy-precision shoulder dimension on the face side, which would seem to be 1/8". Or - make it 3/16" with 1/16" on the hidden shoulder side.

Or - where is it written you need two shoulders? Why not 3/8" shoulder on the outer side and a 1/2" tenon. Hidden rail face has no shoulder. Except for you, who knows, and who cares? Glue surface is the same, regardless of how its done - with a nod to Kevin's The thinner and closer to the outside leg face, the longer the tenons can be. With your 2-3/4" legs, this won't really come into play. Also - I often pin or screw from the inside for extra muscle at the tenon joint.


One last thing - your design is elegant with clean lines. With the rail and leg coplanar, there is ZERO room for off-kilter - in any dimension in any direction. I've done it before, and said "never again", until I don't listen to myself and do it again, and the cycle repeats.

Let us know what happens, eh?