Vacuum Table

[Ajcoholic]

For my 4'x4' plenum I used a half sheet of 3/4" starboard and over the past 2.5 yrs it's been awesome.

Bolted to my table, it has the zones sectioned off with U shaped neoprene CNC foam (sits in a round bottomed 1/4" groove).

I use regular 3/4" mdf for my spoilboard. Generally I cut about 5 to 10 thou into the spoilboard and resurface just to clean it up. I flip the spoilboard every few weeks so both sides get cut.

Not having it glued down hasn't been an issue. When the vacuum is turned on the spoilboard gets sucked firmly to the starboard plenum and won't move.

I do sometimes throw a second piece of mdf on the spoilboard if I don't want to cut into the sb. I stopped sealing the edges of the spoilboard since I wasn't seeing much difference, but I use a 10hp regen blower.

Other than cost I'm not sure why using plastic for the plenum isn't more common.

[EricSchimel]

Funny I was just thinking about using HDPE for a new plenum next time I get through my spoilboard. Did you have an MDF plenum prior? If so, how much more suction are you getting now?

[Ajcoholic]

Funny I was just thinking about using HDPE for a new plenum next time I get through my spoilboard. Did you have an MDF plenum prior? If so, how much more suction are you getting now?

I have a better groove system with the starboard. Deeper and more grooves closer together. I'd assume it's better hold down than the lacquered mdf board I started with. But I didn't do any real tests.

The starboard one should outlast me though, and is super stable. I go use 12 machine screws to hold it to the aluminum top on my shopbot. It's a home brew setup.

[waynelocke]

I am just redoing my vacuum table this week and am going to use HDPE. A 3/4", 4' X 8' piece is $225.00. I use a Fein and am going to a couple of lighthouse motors. My plenum has four zones and I use Home Depot round weatherstripping to further refine the vacuum area when needed.

The guy at All Star Adhesive convinced me a few years ago not to use mdf for the plenum. His argument, which made sense to me, was that, especially when using a smaller vacuum source, the vacuum needs all of the help it can get and no mdf , no matter how well it is sealed, is going to be as effective as the plastic.

The difference in price is not that great and I would have gladly paid more while I was sealing my current plenum with a brush and shellac. It was not a thrilling use of my time.

[MogulTx]

Wayne- who in the local area is offering 3/4" HDPE for that amount? I was just looking at 1/2" at Allied in 54 x 96 for $250. I need three sheets for a project.... (Thanks in advance) Monty

[waynelocke]

I am not at my desk but I am pretty sure that it is Austin Plastic and Supply (512-836-1025). They quoted me that price last week. If that is not the right place, I will repost tomorrow.

[curtiss]

In my table, I drilled a number of 17/64 holes through the “high spots” of the vac plenum. This allows lag bolts from below to hold about anything using “pull down” rather than hold down. (you do have to miss the bolts)

Holes are 5 1/2 inches on center. Did not see any major leak problems when using the vac table, I tape the bottom of the holes which are not used often..

I use some “threaded T nuts” on the bottom of several holes which can be used for threaded screws / clamps from above.