How thick of foam seal to sue on my vacuum pucks?

[knight_toolworks]

I made two vacuum pucks today. I used some ¼” corian that I routed grooves in drilled holes and made two pucks that have separate hookups for top and bottom. Then I glued them together and installed fittings. I used some closed cell vacuum tape that is 1/16” thick I think on both sides. The pucks are 8x10” I noticed I can make the wood jiggle when I only use one. It does not move anywhere but it will vibrate. I get the same thing with this really sticky double sided foam tape,
When I used two pucks it was rock solid. I am using a small vac pump that goes down to 29”
sorry I forgot to take pics of them

[Brady Watson]

Thickness of your gasketing is directly proportional to the thickness of your material. Also, surface condition/smoothness of your material's surface matters too. Double-suction pods are a neat idea, but can catastrophically fail if you break thru the top vac chamber. It would be better if you screwed them down to the spoilboard.

-B

[knight_toolworks]

my material is 2" thick. not sure what you mean really. or do you mean the smoothness of the material?
but they would fail anyway if you lost vacuum right? the puck would stay in place but the wood would go flying. I don't plan on cutting through while I use them at least not for these jobs. I am holding solid wood 8/4 purple heart.

[harryball]

I use 1/16" gasket for smooth flat material. For my purpleheart and small cedar projects I use 1/8" gasket. For my large cedar project where I'm holding a 2x8x48" board I use 1/4" gasket.

What Brady means with a dbl sided puck is if you loose suction not only could your board fly off but the puck along with the hose and fittings could get snatched up. The hose could get snagged and wrung around the bit, metal fittings could be come shrapnel and so forth. I never rely on the same vac to hold the puck down as holds the work piece. I either screw it down or use a 24" x48" puck (I'm not sure if you still call it a puck at that point) and lock it down to one zone using my vac table.

Robert

[bcammack]

Blick pods use an o-ring on the down side and a rubber face on the up side, surrounded by foam gasket. I suspect that the rubber face is to add traction to neutralize that tendency for the held material to shift on the flexible gasket and eliminate that "jiggle".

[knight_toolworks]

good idea all. I can see using a second pump though right now thats out. I do have a large oil filled one but it is a bit much for what I am doing. but when I cut through I doubt I will use them till things are worked out far better.
I think the idea of the rubber and I will go fetch some today.

[knight_toolworks]

any idea's for cheap puck material? I think I will make a sacrificial board to fasten pucks to the board will be held with the vac table.

[harryball]

I use regular MDF sealed with slightly thinned shellac. The thinning allows it to really soak in and seal. I used this first because it was available but it worked so well I kept using it. While it's a little more trouble than some other materials due to the extra step of sealing... it's cheap and plentyful in my shop. Watch out for swelling and warping on large pucks, letting the first coat of sealer dry before applying the second seems to do the trick.

Robert

[jhicks]

Steve, I suppose Cheap is the key word but almost anything Non Porous and flat will do the trick. As Randall says sealed MDF works but If you get your hands on the Celtec, Komacel, Komatex, PVC, Azek or the like in 3/4" to 1" , they make nice pucks. Usually you can talk a supplier or factory out of a few 12" x 12" samples to test so can't get much cheaper than free samples and there is no sealing required. Just set up gasketing tape like allstar adhesive in the shape one needs, port a hole from the side and top to hook vac hose/valve to and you're off to the races

[harryball]

Whose Randall and where does he get off stealing my ideas? :-) Sorry Jerry, couldn't resist.

Don't forget corian, if you can find a local cabinet shop that'll let you have some sink cut outs you can make some nice pucks as well.

Now I have a question, how do you guys secure your vac hose so it is safe and doesn't come up and touch the back of the material? I've used different tapes but I have to check them often or eventually they come loose. There is always some residue dust on the MDF spoilboard killing the tapes holding action. I thought about screwing it down with clips, but that seems overkill.

Robert

[knight_toolworks]

I need to hunt around for free corian my first ones were from some I bought on ebay but not super cheap.

[Gary Campbell]

Steve..
Also try Plexiglas, Starboard, PVC Solid & Foamboard (dense) I like the plastic products as they are not porous, dont require sealing and usually wont warp or swell like an mdf or plywood product. If not available try hard maple. A light coat of a lacquer wont hurt.
Gary

[jhicks]

Sorry Robert, Guess I was confused. Not sure what you mean by your "secure vac hose" question so can't help with that one.

[harryball]

The hose connected to the puck runs up under the material for the small generic puck. i.e. a 4" x 4" puck can hold a 6" x 6" board down that may have an outside profile cut on it, the hose will be up under the material. Or in one case I could use 2 x 4" pucks to hold down a longer board and chain the pucks together.

Robert

[jhicks]

I get it Robert. No secret ideas here. Just whatever is simple and effective in your environment. They do make some plastic "U" clips that stick with double sided tape or velcro but in the end dust free is still key to success. Maybe paint up a small section 1" square or shellac it for a smooth stick surface if you frequently use the same spot?