What kind of grid material for torsion box oak table top

[mensikd]

Hi guys.

I'm almost done with oak panels for torsion box table for my son. Now I'm not sure what kind of material to use for a grid - if it has to be the same material as the top (oak), or it does not matter (e.g. plywood).

Is it possible to use plywood as a grid material on which will be table top glued? Are there any risks regarding restricting table top movement (table top cracking, etc.)?

 

Please advice.

Thank you.

 

BR,

  David.

[..Kev]

Welcome to the forums.

Are your layers solid oak or oak ply?  How big is this going to be?

Not sure I'd want to use solid wood for a torsion box because of wood movement.

As for the grid, ply or MDF work just fine.  I built 2 using MDF and then surrounded with a hardwood trim.

[G Ragatz]

I agree with Kev - I don't think I've ever seen a torsion box with a solid wood surface.  If you want the solid wood top for appearance reasons, I guess you could build the torsion box itself with a plywood or MDF skin and attach the top with clips that will allow for seasonal wood movement.

[mensikd]

AAAh,

you are correct. I did not realize, that torsion box is not made with solid wood top.

Thanks to clarify my mistake, I will try to solve it.

 

BTW - size of top is 80cm x 140cm - approx. 30" x 55". Thickness of solid wood top is 15mm (approx. 0.6"). Thickness of tops with inner grid is planned to be 10cm (4").

 

BR,

 David.

Edited October 14, 2019 by mensikd

[BillyJack]

We would just use plywood half-lapped for torsion boxes in restaurants Most of these were 24-36×144....

[wtnhighlander]

4 hours ago, G Ragatz said:

I agree with Kev - I don't think I've ever seen a torsion box with a solid wood surface.  If you want the solid wood top for appearance reasons, I guess you could build the torsion box itself with a plywood or MDF skin and attach the top with clips that will allow for seasonal wood movement.

This seems like a good solution. Build the inner structure of the box from engineered material that suffers negligible movement with humidity changes, including the under side. Then attach the 'lid' of the box, the show surface, with fasteners to allow expansion and contraction of that surface.

[Mark J]

I am wondering if a top were attached loosely enough to allow for seasonal movement whether it would then be stiff enough for the torsion box to function?  I think you would have to have at least a thin plywood skin under the show top.  Or did I misunderstand what people are suggesting?

[G Ragatz]

35 minutes ago, Mark J said:

I am wondering if a top were attached loosely enough to allow for seasonal movement whether it would then be stiff enough for the torsion box to function?  I think you would have to have at least a thin plywood skin under the show top.  Or did I misunderstand what people are suggesting?

I was suggesting the OP build a complete torsion box of engineered material and then attach the top to that, for "show."

[BillyJack]

A torsion box should have a top and a  bottom....