Frustrating wood warping

[martin77]

Can anyone help with this problem, I'm building a box and I keep getting this problem with the wood bowing. The ply and the Poplar is completely straight but always seems to bow once it's glued? I'm using clamps every 6ish inches while the glue setting

 

[profchris]

Two possible reasons. The glue introduces moisture and the wood moves. Or you've clamped it up with a slight bow, so it holds that after drying.

I'd clamp to a flat stable surface, like a workbench, table top, or a 2 x 4 on edge and leave clamped up for 24 hours.

 

[niall Y]

There is probably a degree if differential movement of the separate wooden elements - think of a bi-metal strip. Are these long thin boxes that have to be that length, or are you gluing up long lengths to cut up later? if it's the former, then it might be a case of experimenting with various options:

1 Make sure that the wood has time to acclimatise to room temperature before gluing.
Trying to glue up in a damp, cold workshop this time of year can be fraught with problems.

2 Try clamping the larger strip to a known flat surface before gluing the other pieces . on.

3 A version of 2, but having a slight opposite curve to the surface you are clamping to..
Very much a case of accepting what is happening, but trying to counteract the worst effects

 

[martin77]

Two possible reasons. The glue introduces moisture and the wood moves. Or you've clamped it up with a slight bow, so it holds that after drying.

I'd clamp to a flat stable surface, like a workbench, table top, or a 2 x 4 on edge and leave clamped up for 24 hours.

I've thought the glue was causing a problem tp be honest, it's all clamped down to a flat surface.

 

[martin77]

There is probably a degree if differential movement of the separate wooden elements - think of a bi-metal strip. Are these long thin boxes that have to be that length, or are you gluing up long lengths to cut up later? if it's the former, then it might be a case of experimenting with various options:

1 Make sure that the wood has time to acclimatise to room temperature before gluing.
Trying to glue up in a damp, cold workshop this time of year can be fraught with problems.

2 Try clamping the larger strip to a known flat surface before gluing the other pieces . on.

3 A version of 2, but having a slight opposite curve to the surface you are clamping to..
Very much a case of accepting what is happening, but trying to counteract the worst effects

Theyre cut down very slightly. And glued in the house and left to dry in a spare room. I'll give the opposite curve a bash though.

Would sealing the 3 other sides before glue be worth a try?

 

[Cabinetman]

Shame, but it’s all experience.
Wild idea, next time glue a piece of ply to the other side as well to form a box then hope it’s done it’s job and after a while cut the scrap ply off.
Please note I am not guaranteeing this at all!
Ian

 

[martin77]

Shame, but it’s all experience.
Wild idea, next time glue a piece of ply to the other side as well to form a box then hope it’s done it’s job and after a while cut the scrap ply off.
Please note I am not guaranteeing this at all!
Ian

Aint a bad idea.

I was wondering if it was due to me using way too much glue.

 

[Cabinetman]

Maybe, but I was thinking could you use screws? Those lost head flooring ones for instance.
Ian

 

[Crazy Dave]

My first thought was has the wood been kiln dried, because I've had no end of problems with wood from Wickes which was straight when purchased but when left on the shed floor has curled up and twisted with sap pouring out of it. Just sharing my thoughts.

 

[martin77]

My first thought was has the wood been kiln dried, because I've had no end of problems with wood from Wickes which was straight when purchased but when left on the shed floor has curled up and twisted with sap pouring out of it. Just sharing my thoughts.

All my wood is Kiln dried, so far I've tried Accoya and poplar onto marine ply. I think I've narrowed it down to either too much glue or over clamping or a combo of both.