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Forum topic by Bohaiboy posted 08-07-2017 12:39 AM 998 views 0 times favorited 4 replies Add to Favorites Watch
View Bohaiboy's profile


76 posts in 2397 days

08-07-2017 12:39 AM

Happy Sunday afternoon to all. M&T question. I am joining a portion of a table apron (3/4” stock) x 5” tall, to a leg that is 1 3/4×1 3/4. The apron will be set back from the edge approx 1/8”. The length of the apron is approximately 20”. I have attached a drawing to illustrate what I mean by a portion.

What depth should I make the mortise? I am thinking 1”. And I am thinking the tenon should be 1/4” as that leaves 1/4” on either side vs making it 1/3 and only leaving 0.2083” for each shoulder. There will only be 3 1/2” of the apron against the leg.

-- Tim, Houston, TX area

4 replies so far

View Loren's profile


10477 posts in 4251 days

#1 posted 08-07-2017 12:45 AM

While 1” is not unheard of, since it is a handmade
piece I would recommend going to a little more
effort and making the mortises intersect. The
tenon ends can be mitered or notched out to
meet in the intersecting mortises.

View TungOil's profile


1371 posts in 1098 days

#2 posted 08-07-2017 12:46 AM

If I were making that I would use a 3/8” x 2-1/2” tenon and go as deep as possible without interfering with the adjacent tenon from the other apron.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

View PPK's profile


1634 posts in 1413 days

#3 posted 08-07-2017 03:33 PM

I agree with Loren. The traditional method is to make the mortises intersect.

I cheated a little and instead of mitering the tenons, I stuck one in full-length, then just chopped the other tenon to fit. It ended up a lap joint inside there. I really don’t think its hugely critical.

As concerns size, I’d go with 3/8” tenon. If you’re concerned with shoulder size, you could go down to 5/16”. If you are using a mortising machine, anyway. Most hand chisels are not made in 5/16”, so that’s not a good option if you’re chopping by hand. I know that the standard method is to have tenon about 1/3 of stock width, but I usually prefer them a little thicker.

The reality of the matter is, M&T joints are so strong, I think you’ll be okay no matter what method you choose, as long as you take your time and make a good, snug joint and glue well.

-- Pete

View runswithscissors's profile


3081 posts in 2628 days

#4 posted 08-09-2017 05:05 AM

I can’t see that the shoulder width is of much significance. I use 5/16 tenons as I have a mortising machine with a 5/16” chisel, and thicker tenons are obviously stronger. Of course if you are doing them by hand, that’s a different matter.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

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