Should I reinforce picture frame corners

[Mike Henderson]

I used to think that glue, by itself, was sufficient for miters. I made jewelry boxes with mitered corners and used to just glue them. Then, one day, I dropped one and one of the corners came open. Since then, I put an FF biscuit in all my miters. Even with the biscuit, I think a corner can come loose if you drop it hard enough or enough times but it will last longer than without a biscuit.

Mike

[Warren Lake]

dowels work fine, wouldnt make it without something.

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[Jeff Ramsey]

Like Martin, I've a jig to cut slots in mitered corners for splines. I glue up the miters then spline them after, usually with a contrasting wood species. The miters will never come apart with a properly inserted spline. A suggestion on a jig; make the part that supports the miter replaceable to reduce tearout since exactly aligning the slot with your table saw blade each time it's used is a challenge. Just replace these strips and you get complete support each time. Obviously this only needs to be done when the jig is set up for a fresh round of spline cuts.

[Steve Demuth]

If your frames are from narrow stock, miters are perfect, and you properly size and apply glue on both pieces, and get a tight enough clamp, most frames will hold together fine. Several hanging in my house and my kids' places that way for years. But wider material, unless in a climate controlled environment, is at risk due to miters wanting to open up on the inside as wood shrinks, and any frame is stronger and more imperfection-proof with a spline, key spline, or dowelled. Personally, for anything larger than a 5 x 7" desk frame, I use external splines cut in to the corners after glue up, as shown above by Martin. As Jeff says, it's easy to make them a design element.

[glenn bradley]

Sounds like it is already assembled. With those dimensions I would reinforce. The spline jigs shown will do it, you just want good backing and tight pressure so you don't tearout at the exit. A quick and dirty one:

Miter-Key-Jig-old.jpg


Replaced by a more elegant one with replaceable inserts (for a clean exit) once it wore out.

Miter-Key-Jig-in-use 006.jpg

[Robert Chapman]

I use a 23 gauge micro pin installed on each corner with my pneumatic pinner and TiteBond III and have never had a problem. Most of my frames are 8X10.