Thread: Mortice & Tenon deepness

You can haunch the tennons over each other, which will allow you to get more depth and a better job.

Another way is to cut the ends of the tenons at 45 degrees so that they form a mitre where they meet inside the mortice.

A 3rd possibility is haunched through tenons, à la arts'n'crafts.

I'd only have the one through tenon, with the offset two wouldn't look right on your design, but it would be possible to "key" it to the other to lock it in place.

Lot of fiddly work, though...

Possibly stopped pins through the leg and the inserted tenon, inserted from the inside face, but not coming all the way through.

With the tenon glued and inserted into the mortice, it would be pretty easy to introduce a pin or dowel to lock it in place.

As said above, haunched tenons would be the classical answer.

I understand (but am open to correction), that the general rule of thumb is that the tenon length should be about 2/3 of the size of the member with the mortice in it, so for a 42mm wide leg, the side tenon would be around 28mm.

Originally Posted by Auld Bassoon

I understand (but am open to correction), that the general rule of thumb is that the tenon length should be about 2/3 of the size of the member with the mortice in it, so for a 42mm wide leg, the side tenon would be around 28mm.

i agree that is a good rule of thumb, but there are always exceptions. where the load on the joint is not too great you may not need to go that deep, eg thick table legs to give a solid appearance to the piece would not need to be mortised more deeply than a thinner leg still capable of supporting the table.

another technique that can be useful is to do double mortise and tennon joints (ie two tennons on the end of the rail fitting into two mortises in the leg). this allows you to use shorter tennons but still increase the glued area of the joint.

I really dont think I have the time or experience to do haunched or mitred joins, but having the double tenon could work...

The tenons (at the moment) are 30x10mm, is that thick enough to be able to use a 15mm mortice with?

If not, I could try two 10x10mm tenons at 20mm deep if I make the legs 10mm thicker

laxation, the shoulders on the tennon dont have to be real wide, just a mm or 2 to cover the edge of the mortise so it all looks nice and clean and covers up any little mistakes. cut the shoulder then cut the tennon in half to make the double tennon, then cut the two mortises to match. that way you are using as much of the original stock in the tennons as possible for greatest strength and creating a huge glue surface area