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Joined: Jul 2004
Posts: 122
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Joined: Jul 2004
Posts: 122 |
Hello everyone,
I am building a curved glue lam for an upcoming project. The arch. has spec's Unibond 800 adhesive. Does anyone have experience with this glue?
Also, I'm curious to know how much a timber 'springs back' after it's layed-up and cured.
Thanks,
Brock
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Joined: Nov 2003
Posts: 687
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Posts: 687 |
what's the radius, length, section, and material?
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Joined: Jan 2008
Posts: 918
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I've used Unibond for vacuum laminating skins and veneers to glue lams - but never for for structural work.
From memory the glue can be a bit tough to work at lower temps - heat blankets or a warm shop will be helpful in getting a good cure. I'm pretty sure there is a recommended temperature on the tech specs.
Is the glue lam structural? If it is - has an engineer signed off on the manufacturing process and the structural capacities of the glue and the interface to the chosen species?
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Joined: Jul 2004
Posts: 122
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Joined: Jul 2004
Posts: 122 |
Length is 10', material is DF, not sure of the radius, but the curve is 15" over the 10' span. It is structural - it is the tie for a KP truss. The arch. has recommended 3/4" laminations.
The plans and process have been reviewed by our engineer.
Brock
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Joined: Nov 2003
Posts: 687
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That's a 10'-7 1/2" radius. How deep and thick is the timber?
I don't have any experience with that glue. We've used West System epoxy for all the curved glulams we've made. We didn't get much springback at all -- 1/2" or less.
You'll need to exert a lot of force to bend those 3/4" thick boards that much, especially if the beam is 8x8 or bigger. I would consider using 5/8" thick laminae.
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Joined: Jan 2008
Posts: 918
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Agree with Gabel. West System is what we used at New Energy Works with good success. Pulling 3/4" lams will be tough. 5/8" or 1/2" will add layers and glue - but be easier to pull together.  The curves in the foreground are sawn - but you can see the glue up jig in the background. The wood braces were eventually replaced with the metal angles. Lots of clamps... 
Last edited by bmike; 09/23/09 03:48 PM.
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Joined: Jul 2004
Posts: 122
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Joined: Jul 2004
Posts: 122 |
Thanks guys, for your continued input.
The timber size is 5.5" x 7.5". I will keep you posted!!
Brock
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Joined: Nov 2006
Posts: 850
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Hey Brock,
I remember a little, I think a "rule" was D/200 for hardwoods and D/150 for softwoods. This was for stair stringer curvature but don't see why it wouldnt work for any curve. We used the same adhesive for a circular stair. Worked well, move fast
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