Half-lap haunched mortise & tenon

oscarBravo

I'm contemplating a joinery project, and I'm trying to plan as much of it as possible before I start. Part of the planning involves joining rails to legs, and I'm wondering about the joint to use.

The rails as I've currently drawn them are about 20×40mm, and the legs are 60×60mm. I don't think 20mm is thick enough to cut a traditional one-third tenon, so I came up with a combination of a half-lap joint and a haunched tenon, like this:



The left side shows a plan and front elevation of a leg with two rails, the top right is an isometric view of the assembled joint and the bottom right is a view of the tenon end of the rail.

Does this make sense? Is there a better approach? I don't really want to go down the pocket screw route; I can't help but feel that a well-made joint will be much stronger in the long run. Having said that, I had already considered that a couple of triangular fillets screwed into the back of the joint might help to reinforce it.

galwaydude18

20mm is pleny for the traditional.1/3 tennnon setup. I made a table with 18mm rails and used a haunched mortice and tennon and left the tennon 6mm wide

knickerbocker

Nothing wrong with what you are planning.... the weakness or strength of a joint is all relative to what it's holding together (and the material it's made from), so for example: your rails attached to a 1000mm leg would be on the weaker side or if only 300mm, would be very strong.
Personally I'd leave the haunch off, I think it will give you no extra strength to the joint, and I would also go for a brace on the inner side of the 2 rails screwed to the leg like this:

recipio

I've read tests in 'Fine Woodworking ' magazine showing that there's not much difference in strength between tenons, 'floating tenons' and dowels.
Personally I'd go with the joint you feel most competent with.
I've gone over to the American Beadlock system which is all done by drilling the mortice and using a router cut loose tenon.

oscarBravo

recipio wrote: »

I've read tests in 'Fine Woodworking ' magazine showing that there's not much difference in strength between tenons, 'floating tenons' and dowels.
Personally I'd go with the joint you feel most competent with.
I've gone over to the American Beadlock system which is all done by drilling the mortice and using a router cut loose tenon.

Interesting, thanks. Where did you get the Beadlock jig and the tenons? Do you have a router bit for cutting the tenons?

recipio

oscarBravo wrote: »

Interesting, thanks. Where did you get the Beadlock jig and the tenons? Do you have a router bit for cutting the tenons?

I bought the kit from www.rockler.com but you should be able to get it this side of the atlantic.
Its a 'loose tenon ' system i.e. you glue in the tenon on both ends. Pre -made tenons are available but I stumped up for 3/8 and 1/2 inch router cutters to cut my own.( Imperial only ) The mortice is drilled out with the jig in a series of steps so ends up looking like corrugated cardboard - no finishing with a chisel needed.
I've made a set of dining chairs with it and so far no problems at all.
The best thing is the saving on wood - no need to put a tenon on both ends so you squeeze the most out of the timber.

Hootanany

Would the Festool Domino not suit you better?

recipio

Hootanany wrote: »

Would the Festool Domino not suit you better?

Absolutely, especially the newer, bigger version -- when I win the Lotto

Hootanany

recipio wrote: »

Absolutely, especially the newer, bigger version -- when I win the Lotto

The one I have is brilliant big one i dont know yet jury is out on it.

galwaydude18

Domzilla