Spoilboard.. glue or no glue?

[john_l]

I've seen it versed both ways here. Can I get a recomendation for my situation?

I have 2 of the 9-15 Imperial vacs in home made boxes. PVC to 4 zones. Plenum board glued to base with the cut channels up, surfaced flat.

It works great without a bleeder on it by the way.. I can't hardly pull a piece of plywood off of it and melamine is rock solid.

Anyway.. I am ready to surface 2 sides and put on the 3/4" Trupan.. do I actually glue or silicone the Trupan down or just run some tape around it or something?

Thanks!

[ed_lang]

I put a dab of glue on each of the squares across the entire plenum and a bead between each zone and the outside. Then put the surfaced side of a sheet of Trupan down. Be sure to NOT SLIDE the Trupan or you will smear the glue. Get help to place the Trupan down in the right spot the first time. Then cover the top of the Trupan with either plastic or another sheet of ply and turn on the vacuums and let it suck down tight. Let the glue dry and turn off vacuum. Surface the top and enjoy a solid multi-zone vacuum table.

[richards]

Before I switched to Brady's combined plenum/spoil board (which is the single-most greatest improvement in my shop), I ran some AllStar gasket tape around each zone and then just dropped the spoil board in place. The AllStar gasket tape kept the spoil board from sliding around and provided a good seal. The last step was to smear some caulk on the edge of the spoil board to force the vacuum to pull through the spoil board instead of pulling through the side of the spoil board.

[john_l]

After surfacing one side of my Trupan, I saw how much of a bow "up" at the edges I was getting and it made me concerned about "not" glueing it down in the middle after flipping. After surfacing the opposite side, it is relatively flat. The little bit of warpage I do have left is easily flatened out with the vacuums now.

I was thinking gasket tape but I'd be worried it would cause the bleeder (trupan) to ride "high" over the tape and sink in a little over the plenum squares. Maybe I am off and it just doesn't do that.

Well, I don't have to tell most of you guys but Trupan does bleed very well. Mine holds material about as good with the Trupan as it does without a bleeder at all.

Also wanted to ask... if I glue the trupan down, and it eventually gets resurfaced to the top of the plenum... wouldn't I have to reseal the plenum (at least the tops of the squares) each time I take it down this far?

Sorry for the stupid questions. Continued Thanks

[richards]

John,
Gasket tape (at least the size that I use) is 1/16th inch thick. I place a few 1/2-inch squares around the table to support the middle of the spoil board. So far, I've never had a problem with a 'cupped' spoil board.

[john_l]

Thanks for clearing that for me Mike. By the name of it I pictured it like a thick foam tape. I need to get some of that stuff.

[ed_lang]

If you glue, you will not need to re-seal the plenum.

[beacon14]

One big benefit of the bleeder board, other than keeping your plenum from getting chewed up, is to help maintain the vacuum when cutting all the way through the material. Without the bleeder board a through cut will allow too much air to pass and you risk losing the vacuum.

With the T-track embedded in my plenum I don't have the option to glue the bleeder board down. Once the bleeder board gets thin there is a tendency for it to curl up some at the edges, but rarely enough to cause any problem. I can see the benefits of gluing the bleeder down but I have made it this far without doing so so I don't think it's critical. When necessary I'll brad nail the edges to the plenum, and I usually run a piece of Gorilla tape around the perimeter of the table (with the vacuum on) to seal the edges and keep dust from working it's way in between the plenum and the bleeder.