Cutting floating tenons by hand

[Aaron Liebling]

I'm working on a base for a credenza which is shaped roughly like 3 sides of a picture frame (or a U), with two vertical legs joined to a bottom base. The legs and base are mitered at 45 degrees and I confess to having cut them to length and mitered them before thinking that I should have left extra material for a tenon...doh! Nevertheless, I'd like to provide extra strength beyond just the end grain glue-up (The thickness is 1 1/2" and width of the miter ~4").

Is there a decent way to cut/drill the mortise for a floating tenon in mitered end grain? In long grain, I'd use some combination of the drill press and chisel. I don't love digging out a mortise on end grain, but the material is thick enough that I think I could do that if there's no better idea.

Alternatively, is there a better way to add strength than the floating tenon? Also, I have to do another set of base and legs (for the rear of the credenza)...would it be best to do integral mortises for those? I've never cut a miter with a tenon integrated in to it, but it seems doable (if not as simple as just sawing off the miter at 45 degrees).

All thoughts appreciated!

[Ben Ellenberger]

My first thought, if I was going to join two pieces at a right angle with a miter showing, would be to try a full-blind dovetail. I haven’t done one of those before, but it might be worth trying in scrap to see.

[Tom Bain]

You could just use a splined miter, which would be simple to saw and chisel. Use a contrasting wood if you want to highlight the spline. Use two splines for more strength. Alternatively you could do a dovetail spline for even greater strength. Although I did these on a router table with a dovetail bit, but could be cut by hand.

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[Aaron Liebling]

Thanks, Tom. I'd considered a splined miter, but really wanted to preserve the clean view from the front - this was because i always thought of splined miters as what they call "case miters" here: https://www.woodcraft.com/blog_entries/splined-miters. A "frame miter" would do the trick with minimal visibility. That said, I'd still rather keep the joinery entirely invisible...which makes me think of a frame miter that doesn't go to either end..which is effectively just back to a floating tenon.

Here are some photos to help visualize the pickle I've gotten myself in to. The two sides turned out beautifully and I really should have thought about how to join them before getting this far! Lessons we learn...

Also, since I have to repeat the whole thing for the back and haven't cut those yet, thoughts on the optimal way to add strength to the next set of miters like these would be much appreciated!

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[Jim Matthews]

Some variant of a gusset, perhaps?

Rather than drill through the remarkably tidy corner, rout out a 1/2" deep "pocket" and glue in a plywood gusset across the joint.

I would go farther and recommend a corner block as well to increase your long grain glue surface.

[Derek Cohen]

I'm working on a base for a credenza which is shaped roughly like 3 sides of a picture frame (or a U), with two vertical legs joined to a bottom base. The legs and base are mitered at 45 degrees and I confess to having cut them to length and mitered them before thinking that I should have left extra material for a tenon...doh! Nevertheless, I'd like to provide extra strength beyond just the end grain glue-up (The thickness is 1 1/2" and width of the miter ~4").

Is there a decent way to cut/drill the mortise for a floating tenon in mitered end grain? In long grain, I'd use some combination of the drill press and chisel. I don't love digging out a mortise on end grain, but the material is thick enough that I think I could do that if there's no better idea.

Alternatively, is there a better way to add strength than the floating tenon? Also, I have to do another set of base and legs (for the rear of the credenza)...would it be best to do integral mortises for those? I've never cut a miter with a tenon integrated in to it, but it seems doable (if not as simple as just sawing off the miter at 45 degrees).

All thoughts appreciated!

Aaron, you probably will end up drilling a mortice for a floating tenon. I would not bother to straighten the ends with a chisel - this is tough into end grain, and you run the risk of blowing out a side. Instead, just round the tenon to fit. Use mortice and tenon if the area is short, and a spline if long.

Other ways of joining mitres include biscuits and dominos. These are simply mechanical methods for the same floating tenon.

Regards from Perth

Derek

[Jim Koepke]

Another alternative would be dowelling inside the mitered corners.

jtk

[James Pallas]

Glue up your joint with good practices. When dry drill for a dowel on the side that won’t show, glue in your dowel. If both sides show use dowels. Biscuits work too but more finicky to do and you need the tool.