Question about using a biscuit joiner on mitered corners

I keep seeing people online trying to glue up big mitered corners for a frame without any reinforcement. It's a mess waiting to happen. I had a client bring in a huge picture frame they made, and the joint popped after two days in their sunny living room. I always use my Porter Cable biscuit joiner to slot in a few #20 biscuits on anything over 24 inches. The wood moves, and glue alone won't hold it. What's your go-to method for keeping those corners tight?

3 comments

3 Comments

kimmurphy11d ago

I read an article in Fine Woodworking that said even small frames can benefit from reinforcement. They tested mitered joints and found glue surface area is just too small for long term strength. I've had good luck with those little plastic miter connectors you sink into a slot, especially on painted stuff. For clear finishes, I'll spline it with a contrasting wood strip, which looks pretty cool actually. Biscuits work, but you have to be really careful with alignment on a thin frame edge.

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janah8311d ago

Totally agree on the glue surface thing, it's basically just end grain holding hands. Those plastic connectors are a lifesaver for quick shop projects. The spline trick is a classic for a reason, looks intentional and adds a ton of strength. Biscuits can be such a pain to line up perfectly on narrow stock, it's hardly worth the hassle sometimes. Honestly, if you're not reinforcing a miter, you're just hoping it stays together.

lilya7611d ago

My buddy learned that the hard way when his whole picture frame fell apart after a week! He swears by splines now.