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Thread: Trouble gluing miter joints

  1. #16
    Glenn's clamping ears (post #3) allow for directing pressure at 90* to the joint surfaces, which is what you want. These can be made up to suit the job, whether boxes or frames, and can be temporarily attached with hot melt or a paper joint. If using a band clamp, make up corner blocks that will put the force where it is needed.

    It is pretty much impossible to get a starved joint using pva glue unless there is insufficient glue applied in the first place. Pvas work best with minimal gluelines. Miters may need a double application due to absorption into the partial end grain surface. Fat joints indicate insufficient or mis-directed pressure, old thick glue or the glue setting up before pressure is applied.

  2. #17
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    Quote Originally Posted by Lee Schierer View Post
    You are essentially gluing end grain, so you want a good amount of glue. I've made dozens of picture frames ranging in size out of various woods. I use Tite Bond II. I also use a picture frame clamp similar to this, except mine are commercially produced and made of aluminum.
    Attachment 497919
    I prefer TB original for most things, including frames, but wow this threaded rod clamp for frames is genius! Thanks for sharing.

  3. #18
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    Quote Originally Posted by jim gossage View Post
    I am having problems gluing up my miter joints on picture frames. During the test fit using a band clamp, the miters are perfectly closed, and with pretty strong clamp pressure there is no frame deformation or twisting. For the glue up I use tite bond III and rub a thin layer of glue on each miter edge with my finger and this takes about 2 minutes to get them all 8 edges done. Then I add the band clamp and carefully pull the joints together, about another 1-2 minutes. In the end, there is a very slight gap in some of the joints, I assume due to glue film. The gap is uniform so the problem does not seem to be with miters that are 0.1 degrees off one way or the other. What is the preferred way to glue these joints? A different glue? Just coat one side of each joint? Glue 1 or 2 joint first and dry fit the others during clamping, then come back and glue them?
    Can you describe what type of gap gets created when gluing? Since you test fit with the clamp first - it is not obvious to me why adding glue would change the fit/gap. (possibly something slides easier with glue - or doesnt slide - vs dry clamping). Maybe if the glue dries out before the clamp pressure is applied? Use more glue to allow squeeze out, or switch to a slower drying glue?

    I always try to reinforce mitered frames with a spline or even a small domino if possible. The domino can 'help' alignment (or fight it if the domino isnt in the right location). Often I can use regular clamps if a domino since the joint isnt sliding around during clamp pressure.

  4. #19
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    Quote Originally Posted by Carl Beckett View Post
    Can you describe what type of gap gets created when gluing? Since you test fit with the clamp first - it is not obvious to me why adding glue would change the fit/gap. (possibly something slides easier with glue - or doesnt slide - vs dry clamping). Maybe if the glue dries out before the clamp pressure is applied? Use more glue to allow squeeze out, or switch to a slower drying glue?
    Its a pretty narrow gap (maybe 0.005") across the length of the joint from inside to outside corners when looking down on it. The wood is curly maple. Its still lined up properly so I don't think sliding was the problem. It just looks like there is an invisible shim in the joint, which makes me think the glue dried a little before clamping and left a bit of a film that couldn't be squeezed out. I haven't tried to break it but the glue up seems very solid. I'm probably making much ado about nothing - I'm one of those woodworkers who aims for machinist tolerances! It was a gift so I don't have it available to take pictures anymore.

  5. #20
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    Glenn, what are those clamps called that you used on the box, and where did you get them? Thanks
    "What you see and what you hear depends a great deal on where you are standing.
    It also depends on what sort of person you are.

  6. #21
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    I frame for 2 local artists, most in poplar, oak or maple. I tend to use whatever glue bottle is closest. Here is the clamp that I use. I have bought longer lengths of 1/4-20 threaded rod for larger frames. To reinforce the joint, I used wide crown, thin staples. So far, so good.

    https://www.leevalley.com/en-ca/shop...ay-speed-clamp
    Grant
    Ottawa ON

  7. #22
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    Quote Originally Posted by Patty Hann View Post
    Glenn, what are those clamps called that you used on the box, and where did you get them? Thanks
    Grant has a link in post #21. I have one of the Lee Valley and one of the Woodcraft versions. The Lee Valley are quite a bit nicer. I have a few lengths of all-thread to make them more versatile.
    "Never underestimate the power of negative people in large groups." - George Carlin (paraphrased)

  8. #23
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    That's the one I have. My tip is to add wing nuts on the end of those long threaded rods. When I'm handling them, you can whip the clamp around, and those brass knurled knobs can fly off into distant corners of the shop, never to be found again.
    Hobbyist

  9. #24
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    I have the same threaded rod clamps. They work.

    But - if it is glue drying out before clamping it might not be a clamp issue...

    Since it is already 'partially' end grain (as a 45 miter), I would have concerns on strength since the joint didnt pull tight. As mentioned, I have had some come loose after a few years so now put a spline or some other reinforcement in everything.

  10. #25
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    Quote Originally Posted by glenn bradley View Post
    Grant has a link in post #21. I have one of the Lee Valley and one of the Woodcraft versions. The Lee Valley are quite a bit nicer. I have a few lengths of all-thread to make them more versatile.
    Thanks... (thanks to Grant too)
    "What you see and what you hear depends a great deal on where you are standing.
    It also depends on what sort of person you are.

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