Tenon in a miter?

[Eugene Krimkevich]

Hi all,

I'm working on a side table of questionable design integrity and figured I'd get some second opinions. I originally planned for the piece to come together as in the attached photos - the base is a mitered frame, as is the top frame (which will accommodate the actual tabletop). The tabletop will consist of some walnut boards edge-glued together and secured to the top frame using buttons (hence those slots in the top frame). I was planning on joining the two frames with two tenoned legs that will sit in mortises drilled in the corners of each mitered frame (the assembly in the photo). The table will be sitting so that the legs are oriented vertically (basically a cube with a missing side).

My concern is this: will drilling mortises in the mitered corners and gluing a tenon in (and possibly pinning or drawboring the tenon) be a solid-enough joint here? I know the miters are very weak as is, seems like adding a tenon in there will actually increase glue surface? Any thoughts?

IMAG0531.jpgIMAG0532.jpg

Thanks,
Eugene

[Dave Richards]

You're right. There would be more good gluing surface. That is, not involving end grain. The purple and green faces on the tenon would be glued to long grain on the frame pieces.


However the challenge might be keeping the joint together while cutting the mortise and I'd guess wedging the tenon would be likely to drive the miter open.

A better option for this would be to use a mitered bridle joint to join the corners and mortise that. The mitered bridle would be very strong because of the long grain gluing surfaces and the joint wouldn't be driven apart by chopping the mortise nor by wedging the tenon.

[Eugene Krimkevich]

Hi Dave - thanks for that sketch, super clear and helpful. Never even thought of that option - unfortunately I've already cut and glued the mitered frames If I used a band clamp on the frames as I drilled the mortises, would that help keep the glue joint together at all?

[Dave Richards]

I'm sure a band clamp would help. Can you get some pipe clamps across the frame? I think they'd be more rigid. Run them in both directions.

I wonder if you've got room to run some dowels in across the miter. one on the inside and one outside of the mortise would add a lot of strength.