How do you attach vacuum plenum to support board?

[gerald_martin]

I have cut an MDF vacuum plenum which I need to seal yet. It seems to me that this should be glued to the plywood support board...if so, how?

Wood glue or contact cement?

If I use, say wood glue, and coat the support board, then lay the plenum on: If I lay a 4x8 sheet of something on top of the plenum, will that compress the plenum against the support board to get a good tight bond?

And will too much wood glue squeeze out and go down my pvc vacuum manifold piping?

Will the vacuum pull out any air pockets and compress the mdf to the support board? Or will the vacuum only pull the plenum boad to the sheet above it and NOT compress the plenum to the support board?

Anyone?

GM

[woodworx]

wood glue works good, plus it doesn't add any thickness an any areas like silicone would. Screw from under your support board or load 10 sheets on your vacuum board to push it down while the glue dries.

[beacon14]

If you have the vacuum plumbing hooked up then using the vacuum is the best and easiest way to glue the plenum layer down. Apply glue to the plywood, lay the plenum on top, then lay a sheet of melamine or other non-porous material on top of the plenum (even plastic sheeting will work). Then turn on the vacuum.

Don't worry about a little squeeze-out getting into the PVC pipes. It's more important to have a full, even coat of glue between the layers. A roller or piece of scrap wood used as a squeegee works well.

[gerald_martin]

Thank you for the ideas. I do have vacuum hooked up and this seems to be the most practical. How long would the vacuum need to run? one hour?

Gerald

[beacon14]

Whatever it says on the glue bottle, double that to be safe.

[pfulghum]

I don't glue it, screw it down about every 6".... that way *IF* you cut through the plenum by accident, you don't have to replace support board.
-- pat