Workbench top - mixing ply or mdf with sold wood..?

[Vince Lok]

Hey guys, I've been looking to make a new workbench and I happened across some unknown wood that is 1/5 inches x 9 inches and about 5 feet long (about 4 pieces) . It's pretty straight and I thought I might be able to use it as a workbench top. I'm not a pro or anything so I think it will do what I want (hold a front vice and provide an overhang for clamps).

Since it's only 1.5 inches thick, I was thinking I could bolster it by using 3/4" plywood under it. Or even use a 3/4" MDF board on top of it to provide a flat surface.

However, given how wood moves, could I actually attach the ply to the solid wood without massive warping problems? (I'm guessing the ply would not move, but the solid wood would move around agains the ply and arch upwards)? If I sandwiched the solid wood in plywood and/or MDF...well shoot, then I might as well not even use the sold wood and just build a torsion box, right?

Should I just have a thin 1.5 inch solid top? Again, I'm not sure what type of wood it is, it used to be a bed or something in my neighbours house (he got evicted after 20+ years and the wood and other stuff was tossed into the backyard). It had a few knots in it and it's stained a dark colour.

Thanks!

Vince

[Jeff Dege]

I built a bench last spring using two sheets of 3/4" MDF and a slab of IKEA countertop - 1-1./2" thick edge-glued oak.

I glued the MDF together, and wrapped it with 1/2" thick oak, but just screwed it to the countertop. I routed and sanded the combined edges. When I was done, there was no visible gap.

This fall, the oak is 1/4" wider than the MDF. If I'd glued, instead of screwed, the oak and the MDF, the top would most certainly have warped.

[Shawn Patel]

Post pix of the wood.

[Howard Acheson]

No, you can not solidly adhere the face of solid wood to a composition material. As you state, the expansion/contration rates are greatly different. The solid wood will want to expand/contract with changes is relative humidity while the composition material is essentially not affected by changes in humidity. Warping or other damage will occur.

Make your top either all from solid wood or all from composition materials.

[Jeff Dege]

Originally Posted by Howard Acheson

Make your top either all from solid wood or all from composition materials.

Or fasten them together in a way that will allow for movement between them.

[Dan Henry]

I made a work table/ bench about 15 years ago using 2 sheets of 3/4 particle board with a 1/4 inch replaced MDF top and it has stayed very flat. I have some center support for the top, vertical dividers for drawers and a knee hole. I think I glued the 3/4 together and put the 1/4 top on with 18 gage air nails. Top is 33 X 78, I have replace the top about 4 times and is due again as it is stanied and has drill holes in it.


Dan