Help preventing parts shifting during glue-up

[Josh Rudolph]

I have some parts that I am gluing up, essentially 2 plywood planks 16.75" x 3.5" x .75" each. Alignment is critical. All four sides must be flush when I clamp them.

I have tried rubbing the parts together with the glue between to help the bond and spread the glue.
I have starting clamping from the center out.
I have started clamping from the ends.
I still get a little bit of creep somewhere on the parts.

My glue is Gorilla Glue (I am forced to use it for now as it is the only true waterproof glue I could get quickly for work - HAZMAT issues with others). My plywood is Marine Grade Douglas Fir.

I am considering making a jig, but get concerned with the squeeze out making it a real pain. I was considering putting clamps on the seams, but again get concerned with the squeeze out and mess.

Any recommendations or ideas? Do I need to look at a specific clamp? I used Bessey K-Body.

Making them oversize and cutting back to final dimension is also not an option.

I do have the two options listed above but wanted to see if anyone may have a trick up their sleeve.

Thanks

[Doug Shepard]

I would cut a couple of 3/4" long dowels and drill for them on one piece. Then use dowel centers to mark the 2nd piece while aligning it dry. Drill the holes for them a hair over 3/8" deep and they wont go through the outer ply faces. That will stop them being able to shift when you get them glue on them.

[Chris Kennedy]

Where are you getting the misalignment? Side to side or vertically?

Side to side, you might try pinch dogs. Vertically, you might try cauls across the face. And to some it may be heresy, but a couple of biscuits along the joint can help with alignment.

I've put clamps on the seams before without any problems.

Cheers,

Chris

[Fred Belknap]

Flat side to flat side I sometimes use a couple small brads to keep them aligned. Jig will work just line it with wax paper.
edit: with gorilla glue you just put it on one side and then dampen the other surface I think. Been a long time since I used it.
Fred

[Steve Griffin]

Biscuit Jointer!

-Steve

[Thomas Knapp]

Dowels could line everything up, but can be a little fussy to align. The drill bit might want to wander in plywood so a good doweling jig would be in order. I would probably use biscuits for the face alignment and also cauls with wax paper between them and the wood. A notch in the caul right over the glue joint will keep it out of the glue. Masking tape pulled across the joint in several places will keep the wood from sliding end to end. Gorilla glue is messy stuff! I only use it when there is not a good alternative.
Tom

[Josh Rudolph]

Thanks for the replies so far guys. The Dowels may be the route.

Just two precisely placed dowels should do the trick.

Still considering the jig route also.

[Myk Rian]

I use a couple small brads, or sprinkle a very small amount of sand between the sheets.

[John Coloccia]

Is there a reason why you can't glue up oversized and then cut to final dimension?

[Perry Holbrook]

You could try a combination of glues. Use the Gorilla Glue for the lasting holding power, but during glue up apply some CA glue to a few spots. When you lay up the pieces, you will have a few seconds to align by hand before the CA grabs. It should hold it in place to prevent creep when applying clamping pressure.

Perry

[Lee Schierer]

Apply your glue, then use some clamps from the sides to align the edges like you want. Once you have the sides aligned, apply your clamps the other direction to clamp your faces together. They should stay put.

With polyurethane glue, do not apply water to either part. It causes a lot of foaming. There is enough moisture already in the wood for the glue to cure. The glue will cure a bit slower and with less foaming if you do not dampen the wood. Joint strength is the same or possibly a bit stronger without the dampening step.