glue up question

[Ron Bott]

I have four boards 1/2" thickness, 8"x36" that I want to glue up into a single piece 2"x8"x36". I'm not sure how to go about clamping the boards for this. Should I put glue on both adjoining faces or just one side? If I were to just place some concrete blocks on top of the stack would this be enought pressure for a tight bond? Or should I use clamps, and if so how?

[Joe Chritz]

As long as glue gets on all surfaces that is fine. If that needs glue both sides or one it doesn't make a difference.

Blocks won't be heavy enough it will need even pressure all over.

Do a search for "caul" or go to the bowclamp website. It has info on cauls.

At 8 inches wide if you have enough clamps you can clamp from both sides every 6 inches or so and get good pressure.

Joe

[John Thompson]

Agree with Joe.. you will need cauls on 1/2" and don't apply too much initial pressure with the clamps. I normally put the pedal to the metal with clamps (I work with some thick stocks).. but in the case of 1/2" thick stock, that may cause them to slide if the edges are anything but dead square and might anyway.

I will add.. make sure the stock is acclimated before glue-up as 1/2" stock will have more tendency to bow from the middle than thicker stock.

Sarge..

[Frank Drew]

Ron

Perfect job for a bunch of large Jorgensen hand screws, coming in from each side. Problem is you need a boatload of them, but they'd provide just the kind of deep, parallel pressure you need. If you have some but not enough you can supplement them with other types of clamps and cauls.

To keep your boards from sliding around you can nail a few thin brads in every other board and cut them off so they just stick up a bit but have enough of a point to penetrate the mating board, which you then carefully position after applying the glue. A dry run with pressure to make holes in advance might help, and would certainly make the glueup easier with your clamps already in their near final position.

[Judy Kingery]

Ron, I do what Frank recommended and have had great success with glue joints and even distribution of pressure; the Jorgensons do the job for everything I do anyway. Best to you! Jude

[glenn bradley]

Non-Jorgenson hand screws will work as well :D. One challenge will be keeping the assembly straight. This is a pretty thin lamination so I would tend to add a larger 'known straight' board at one end (no glue).

[Frank Drew]

Also, as for glue, I'd put a thin layer on all mating surfaces; better a little squeezeout than a glue starved joint.

Newish hand screws (Jorgensen or other ;)) often leave some of their oil behind on the work; if this would be a problem you can isolate the two finished faces with paper or laminate or other pieces of wood, such as Glenn's suggested thicker boards.

I would start the clamping with my glue-applied assembly on edge, applying the hand screws from the top, then flipping the whole thing over, clamps and all, to come in with clamps from the other side. Nice thing about hand screws is that their flat butts provide nice stability.

[Greg Hines, MD]

The most effective way to clamp it would be with a vacuum press. That would provide even pressure over the entirety of the piece.

Assuming that you do not happen to have a vacuum press, I would use multiple clamps and cauls to even out the pressure over the entire surface. I would put glue on both sides of each internal member. The other option would be to laminate two pairs together first, then glue the two halves together. Regardless, glue them up on a flat reference surface to keep them flat too.

Doc

[Howard Acheson]

I have four boards 1/2" thickness, 8"x36" that I want to glue up into a single piece 2"x8"x36". I'm not sure how to go about clamping the boards for this. Should I put glue on both adjoining faces or just one side? If I were to just place some concrete blocks on top of the stack would this be enought pressure for a tight bond? Or should I use clamps, and if so how?

What will your glue up be used for? Is it a structural application?