Laminations

[Jason White]

I've been milling some rough 2x6 red oak. I wanted to laminate them together to make 4x4 legs for a workbench. I used lots of Titebond 2 and a few Bessey K-bodies, but still ended up with some "gaps" in-between the laminated boards. The were perfectly flat and square when I did this (used the jointer and planer).

Any suggestions on avoiding these gaps in the future? Any type of cauls or something I should be using? To be clear, I'm laying these on the flat and face gluing them.

Jason

[george wilson]

I guess you should have used many clamps spaced closer together. I don't know how far apart your clamps were,but they didn't make it.Did you place a thick,straight piece of wood under the clamps on both sides?

[Frank Drew]

Jason,

The thicker the wood the more clamps and clamping pressure needed. As George said you need a boat load of clamps -- one every few inches wouldn't be too many. I like wood-jawed hand screws coming in from both sides for that application because with the bigger ones you can get all or most the way across the faces you're clamping.

[Dewey Torres]

If indeed your stock was flat and square and you were using Bessy's chances are it was uneven clamping pressure or not enough clamps. Use the 45 degree rule and overlap the point where the 45 degree pressure intersects and it should eliminate this in the future.

Hopefully this sorry looking SU file will explain. Trying to show the lines of force and the clamps.

[Jason White]

I had them spaced about 6 or 8 inches apart. I think my mistake is that the jaws of the clamps didn't reach all the way across the stock. Perhaps I should have alternated sides?

Jason


If indeed your stock was flat and square and you were using Bessy's chances are it was uneven clamping pressure or not enough clamps. Use the 45 degree rule and overlap the point where the 45 degree pressure intersects and it should eliminate this in the future.

Hopefully this sorry looking SU file will explain. Trying to show the lines of force and the clamps.

[Peter Quinn]

I 'd use more clamps and stronger clamps. i love my K bodies but they are not my go to device for face laminations. Also, if you are making leg blanks, were you gluing up long boards to cross cut later or gluing a sandwich of boards cut just over sized length wise? I like to glue up 4X4 leg blanks in a sandwich, so each layer acts as a caul for the next, I put a piece of plywood top and bottom to protect each face from clamp marks, and clamp the heck out of it with pipe clamps or heavy duty C clamps, something capable of far more pressure than a K body can deliver.

I'll easily glue up four pairs of 8/4 stock or four sets of three 6/4 stock to make a set of legs. A few finish nails toe nailed at the ends keeps things from shifting too much during clamping. Just leave them proud so they can be pulled before milling the blanks further.

[Jamie Buxton]

You might do better with less glue. You say you used "lots". The lumber had flat faces when you started. That is, if you dry-fitted the glue-up, the faces fit together. If you have nice flat boards, the glue line only needs to be a few thousandths of an inch thick. Any more glue than that is excess glue. The clamps have to squeeze it to the edge, overcoming its viscosity, which is getting higher as the wood sucks water out of the glue. If you don't have huge clamp pressures, the glue sets up before it gets squeezed out. That is, the gaps you see in your current process have to be caused by excess glue.