Mortise & tenon advice needed

[Bryan Hunt]

I'm building a frame from 2 3/4" square stock. I could use some advice on how to design the mortise and tenon joints where the rails join the legs. How wide would you make the tenons, and would you offset them toward the outside of the leg to make them longer, or stick with centered in the leg? Here's what the basic frame looks like:

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[Sam Babbage]

Offset would be better just like a table rail to leg, with or without the mitre at the end. Or you could be cute and 3-way mitre the whole thing, easy with a Domino, doable without.

Edit: as to the thickness/width, without drawing it out, I'm on my phone on a train, I'd probably go about 1 1/2 wide 5/8 thick set back 5/8 from the edges, that might be a little off, I'm converting from metric on the fly!

[Bryan Hunt]

Three way mitre would be cool, and I can see where the Domino would be handy. Too bad I don't have one yet :) I was planning on cutting integral tenons maybe 1" wide.

[Carl Beckett]

By looking at this, it seems you need to bring the top rails into the leg and also the side rails into the leg at a 90. So you dont want the mortises to break through to each other (you could, but it might be easier if you didnt).

I might want the tenon width at 3/4", and 1.5" deep. A shoulder (or cheek??) of 3/8" (2" height on the tenon). If you did this, it would risk the front tenon breaking into the side tenon mortise - so I might offset the side tenon towards the outside.

[Charles Lent]

When I do M&T joints I frequently follow the rule of thirds (frequently, but not always). The tenon becomes 1/3 of the thickness of the stock, leaving 1/3 of the thickness of the stock on either side for the shoulders. It's usually the best balance of strength to size. For length I usually try for at least 1/2 of the thickness of the stock that will receive the mortise, but frequently go deeper and make the tenon longer to fit.

Charley

[Bryan Hunt]

Thanks everyone for the advice. I did some more work in SketchUp and here's what I have so far.

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[lowell holmes]

Watch the portion of this video about the tenons. He doesn't miter the tenon ends. He makes incredibly good sense with his approach.

http://www.finewoodworking.com/item/56976/build-an-elegant-dining-chair/

[David Peebles 1]

I make tenons using a tenoning jig on a router or shaper (have done it both ways). I use a straight router bit, and (carefully) do a climb cut, which avoids tear out. As for your design, the other guys are the experts--even when they disagree with each other.