large round m&t anyone?

[Lynn Kasdorf]

Anybody out there ever built things with large, round mortise and tenon joints? I'm building a play structure out of 3x5 landscape timbers, and plan to pick up a 1 1/2" diameter round tenon cutter from Woodcraft.

I've used a 3/4" cutter for a rustic arbor I did, and it went great. I'm hoping that the 1 1/2" cutter will have a large enough openign that I can feed it a 3x5 landscape timber. I think 1 1/2" is about the right size for a round tenon on 3" thick stock. Then next size up is 2", which only leaves 1/2" on either side of the hole.

Opinions?

[Jim Becker]

Even if it "fits" (and I don't think it will even be close), the problem with those round tenon cutters is that they don't leave you with a flat shoulder. You really want that for strength for such a structure. The tenon cutters are really designed for rustic furniture and smaller sized stock. I suspect that for this project you'll be best off with traditional M&T "timber-frame" construction techniques, albeit there is a bit of work involved!

[Ken Frantz]

At one time I was building a rail fence using landscape timbers(still have the project to finish) by drilling the round post (6 inch) with a door lock mortising bit (1 7/8 inch bit) a tad more than the depth of what the hole saw would cut and then using a 2 inch hole saw cutting the landscape timbers on the ends deep as posible and then removing out side with a saw.

For a taper on the end of the rails after the round part, I set up a jig simular to a 8-9 foot lathe bed and had my router set on a platform at the angle needed and turned the timber by hand.

With a little more "engineering" the whole rail could be turned with the round tenion and the taper.

If you want some pic of the operation, let me know by e-mail.

CLEAR AS MUD?????