Glue advice needed...

[stuartmarquis]

I'm a novice to woodworking. I have a passion for table tennis and I want to start making my own table tennis bats. The basic concept is pretty straightforward. A "core" wood which is maybe 3-4 mm thick (most likely balsa due to its light-weight) and then a couple of veneers of a harder wood glued on either side. The issue I'm having is that when dealing with such thin sheets of wood there's a tendency for it to not lay perfectly flat. I basically need a glue that will set rigid so that when the wood is pressed flat whilst the glue is drying the bat then holds that rigid flat shape when its removed from the press. I've tried a couple of bats with PVA Gorilla wood glue and also Titebond Liquid Hide Glue, but both these glues seem to be somewhat flexible even when cured, meaning that when the bat is removed from the flat press it can have a tendency to re-warp.

I need a glue that going to set rigid and hold the plies flat even if the core wood naturally wants to warp a bit. Any suggestions?

Thanks

 

[Phil Pascoe]

Try Cascamite - the stuff on the market now is OK. One of it's failing in chair joints etc. is that it is quite brittle so it may well be OK for your use. It's used for laminated work because there is little/no creep. There are people here far more knowledgeable that me, so you'll undoubtedly get other/better suggestions.
Welcome, by the way - let us know how it goes.

 

[stuartmarquis]

Try Cascamite - the stuff on the market now is OK. One of it's failing in chair joints etc. is that it is quite brittle so it may well be OK for your use. It's used for laminated work because there is little/no creep. There are people here far more knowledgeable that me, so you'll undoubtedly get other/better suggestions.
Welcome, by the way - let us know how it goes.

Thanks Phil. I'll look into this as an option. I also stumbled across fish glue as a potential candidate if you know anything about that (mainly used in musical instrument making, I believe)?

 

[Yojevol]

I had a similar problem with making clock gears out of self made plywood using veneers and PVA. The problem being that too much moisture was being introduced and it would not stay flat as it cured. Problem solved by the use of polyurethane, PU, glue which has no water content. A bit messy to use but it worked.
Brian

 

[stuartmarquis]

I had a similar problem with making clock gears out of self made plywood using veneers and PVA. The problem being that too much moisture was being introduced and it would not stay flat as it cured. Problem solved by the use of polyurethane, PU, glue which has no water content. A bit messy to use but it worked.
Brian

Thanks for the response. I've tried normal Gorilla glue which I believe is a PU glue. The issue I had with this is that the glue foams and expands whilst curing, meaning that the bats became overly thick (although more clamping pressure might solve this issue to stop the glue pushing the plies apart as it cures).

 

[Yojevol]

Thanks for the response. I've tried normal Gorilla glue which I believe is a PU glue. The issue I had with this is that the glue foams and expands whilst curing, meaning that the bats became overly thick (although more clamping pressure might solve this issue to stop the glue pushing the plies apart as it cures).

If it's properly clamped between 2 substantial boards it should not expand.

 

[stuartmarquis]

If it's properly clamped between 2 substantial boards it should not expand.

I had mine sitting between two sheets of 6 mm glass, with a bucket of stones sitting on top of the glass to apply clamping pressure. The bucket probably weighed about 20-25KG which I though was quite a substantial amount of weight, but even so the thickness of the wood ended up about 8mm. When a different glue is used the thickness ended up being about 5mm...3mm is of course a small difference in the grand scheme of things...but its pretty significant in terms of percentage increase!

 

[Phil Pascoe]

Nowhere near enough pressure. You need decent clamps - if that's all you used in the first instance, that's probably your problem.

 

[Yojevol]

I had mine sitting between two sheets of 6 mm glass, with a bucket of stones sitting on top of the glass to apply clamping pressure. The bucket probably weighed about 20-25KG which I though was quite a substantial amount of weight, but even so the thickness of the wood ended up about 8mm. When a different glue is used the thickness ended up being about 5mm...3mm is of course a small difference in the grand scheme of things...but its pretty significant in terms of percentage increase!

In this case I used a 56lb weight pressing down on 32mm MDF. I used 7 x 0.6mm veneers and ended up with a 4.5mm thick ply. If PU is allowed to expand when curing it is going to have very little strength.
Brian