Should I reinforce picture frame corners

[Matthew Curtis]

I have an assembled frame that measures 40" x 14". It is mitered together using Tite bond 3. The frame pieces measure 1 1/2" x 7/8". The frame will be finished with acrylic instead of glass.

Should I reinforce the corners somehow? If so how?

[Lee Schierer]

When you glue the miters together apply glue to both sides. This insures a better bond that just applying glue to one side. To prove it to your self. Make four pieces out of the scrap from your current frame to make two sets for a corner. Then glue one set applying glue only to one surface of the miter. Clamp it and let it dry. On the second set apply glue to both side, clamp it and let it dry. Then the next day try to break the pieces by had and see which won is easier to break.

When gluing miters it is almost like gluing end grain and the glue is pulled into the wood very quickly, leaving the surface starved for glue when the second side also tries to pull glue into it. Applying glue to each side prevents glue starvation.

[Jamie Buxton]

Before you glued it up, you should have inserted a spline in each joint. A biscuit does the job.

As a retrofit, you can find L-shaped metal mending plates at the hardware store. You can just screw them on to the back, or you can inlay them.

[John Patric]

Staple across the miters.

[Cary Falk]

I always use biscuits no matter the size of frames.

[Frederick Skelly]

As a retrofit, you can find L-shaped metal mending plates at the hardware store. You can just screw them on to the back, or you can inlay them.

I did this with a L-shaped piece of 1/8" Plywood, inlaid. It was very sturdy.

For future reference, I did another using epoxy instead of TB. (No spline or L-bracket.) It was also pretty solid.

[Edwin Santos]

I have an assembled frame that measures 40" x 14". It is mitered together using Tite bond 3. The frame pieces measure 1 1/2" x 7/8". The frame will be finished with acrylic instead of glass.

Should I reinforce the corners somehow? If so how?

I always reinforce mitered picture frames. It's a real hassle when a frame comes apart after the artwork has been framed, matted, etc.

Have you applied finish to the frame yet? If no, then reinforce the corners with key splines. I'm not sure what tools you have. A slot for a key spline can be cut on the table saw with a jig, or with a slotting cutter on a router table with a jig. Do you have a biscuit joiner? If yes, you can use it to cut the slot, see the photo below. If you have none of these tools, you can cut the slot with a hand saw.

Glue the keys into place, trim flush, give it a quick sanding to clean it up, and then proceed with your finishing.

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[Mike Henderson]

I like to use a biscuit on those kind of miters. The biscuit is hidden and provides significant strength to the joint. If you've already glued them, do what Edwin suggests in post #7. The disadvantage of that approach is that the key shows, but it's usually not that obvious.

Mike

[Edwin Santos]

Another thought - you could reinforce already glued miters with a dowel. Use 1/8" or 1/4" dowel rod from your hardware store, drill a hole with a handheld drill deep enough that it crosses the joint. Glue the dowel it in, trim flush, etc. To make it less obvious, you could drill from the top and bottom, so when the picture is on the wall, the dowels can only be seen from above or below the frame which basically means they won't be seen. I would do two per joint.

I know a frugal guy who has done this using bamboo skewers and a 1/8" drill bit.

The mitered keys would have more glue surface area and thus be stronger, but I have no doubt the dowels will hold the joint together.

[Jim Becker]

Reinforcing end-grain to end-grain joints like that is pretty essential. For a finished frame, you could simply glue and staple thin plywood "ells" on the back side of the corners as a "retrofit"...even 1/8" thick material will do the job...and it will not materially affect the look of the frame. Just keep the edges of the reinforcement set back from the edges of the frame so they are hidden in the shadows.

[Dan Friedrichs]

I use small Dominos to reinforce those types of miters. Before I had the Domino, I used pocket screws.

[Martin Siebert]

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Using this "over the fence" jig and a table saw cut out a slot in the glued but unfinished frame on each corner. Glue in a piece of wood that fits. I sometimes use contrasting wood. Makes for a pretty strong joint. I have never had one come apart. Easy to do, a lot of folks like the look and it is very effective.

[Tom Bender]

Finishing nails or pin nails work well. Installed from the top and bottom they are not very visible. Predrill and angle them.

[roger wiegand]

I always reinforce, usually by making a diagonal half lap joint-- I miter the corner as usual then cut away half the thickness of the corner on the back and glue in a triangle running the other direction that bridges the miter. It's cross grain but the corners are usually only an inch or three wide. I haven't had one fail yet. I've also done splines in the same way, but that requires more fussy thicknessing of the spline. With the half-lap I put in an oversize board and just plane it to size once the glue dries.

[Chris Fournier]

I've made well over a hundred picture frames and never used a re-enforcement such as a spline or biscuit. Art Frames, not bulky memorabilia shadow box frames. Carefully apply a thin layer of glues to both faces of the mitres and then apply another coating of glue. Clamp and away you go. My mitres are finished with a hand plane so they are tidy. I have tried to break my frames by hand - destructive testing. No go. Try this yourself. Re-enforcement is an option not a requirement. My frames are 25 years old in some cases.

[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:

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

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[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.