Author Topic: Glueing miter joints  (Read 2988 times)

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Offline amt

  • Posts: 374
Glueing miter joints
« on: October 21, 2014, 07:45 PM »
I saw this idea originally on "Rough Cut" woodworking show, so I thought I would give it a try.  I have some very long miter joints which need to be glued up.  To complicate matters, these are not standard 45 degree miters.  The challenge is to be able to clamp, such that you are applying force perpendicular to the miter joint.  The problem is that the surfaces to clamp to are nowhere near perpendicular.  So, what I did was glue "clamp blocks" to the project itself, for the sole purpose of providing that proper angle.  The clamp blocks are cut with the same angle as the miter to cancel each other out:


After the glue has dried, remove the clamps and knock off the glue blocks, leaving the bottom most layer of plywood:


Then chisel off as much as you can without damaging the project:


Then use a sander to clear off the rest:
« Last Edit: October 21, 2014, 07:54 PM by amt »

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Offline jacko9

  • Posts: 2349
Re: Glueing miter joints
« Reply #1 on: October 21, 2014, 08:12 PM »
Nice job,  I have read that you can also use hot hide glue to attach the blocks and then heat them for removal.  I haven't had the occasion to try it but it might be easier that the chisel and sand option?

Jack

Offline Cross-cut Canuck

  • Posts: 133
Re: Glueing miter joints
« Reply #2 on: October 21, 2014, 09:03 PM »
I have a similar job id like to try but im using walnut plywood. Im not sure if gluing the pieces would really work with out potential sanding thru the plywood veneer. I like the idea of hot glue but would it be strong enough? what your thought s on that? does any one else have ex[periance doing this?

cheers

--- MY GREATEST FEAR IS WHEN I DIE, MY WIFE WILL SELL MY TOOLS FOR WHAT I TOLD HER I PAID FOR THEM ---

Lots of Green Stuff and Green things and a few odds and ends...

Offline jacko9

  • Posts: 2349
Re: Glueing miter joints
« Reply #3 on: October 21, 2014, 09:16 PM »
I have a similar job id like to try but im using walnut plywood. Im not sure if gluing the pieces would really work with out potential sanding thru the plywood veneer. I like the idea of hot glue but would it be strong enough? what your thought s on that? does any one else have ex[periance doing this?

cheers

I have read about this technique as I recall in one of James Krenovs books (or was it Tage Frid) and he used the hot hide glue for clamping purposes.

Jack

Offline Arch WW

  • Posts: 32
Re: Glueing miter joints
« Reply #4 on: October 21, 2014, 09:33 PM »
I have for many years used a piece of paper between the glue block and the finished plywood or solid wood. It makes the job easier to clean up.

Offline Cross-cut Canuck

  • Posts: 133
Re: Glueing miter joints
« Reply #5 on: October 21, 2014, 09:45 PM »
I have for many years used a piece of paper between the glue block and the finished plywood or solid wood. It makes the job easier to clean up.

did you use regular wood glue or hot glue?
--- MY GREATEST FEAR IS WHEN I DIE, MY WIFE WILL SELL MY TOOLS FOR WHAT I TOLD HER I PAID FOR THEM ---

Lots of Green Stuff and Green things and a few odds and ends...

Offline Tim Raleigh

  • Posts: 3506
    • Oakville Cabinetry
Re: Glueing miter joints
« Reply #6 on: October 21, 2014, 10:08 PM »
I have for many years used a piece of paper between the glue block and the finished plywood or solid wood. It makes the job easier to clean up.

did you use regular wood glue or hot glue?

Use regular (water soluble) carpenters glue. To avoid tear out, do not knock the blocks off with a hammer, chip them off above the base and carefully plane off the remaining piece of the block, and or dissolve the glue off with water and a sponge. Brown craft paper between the block and the substrate does help the release, but weakens the bond of the block to the substrate. A block sometimes releases when clamping the joint.
Tim
« Last Edit: October 21, 2014, 10:21 PM by Tim Raleigh »

Offline amt

  • Posts: 374
Re: Glueing miter joints
« Reply #7 on: October 21, 2014, 11:18 PM »
In my application here, I was using solid wood for the project.  With plywood, I would want to do some extensive testing first :)  BTW, when I did knock off the plywood glue blocks, they all popped off expect the first layer without fail.  This may be a reflection of just how bad home center plywood is, but in this case it worked to my advantage perfectly.