Vacuum Plumbing

[wardsa]

Sorry, another vacuum question! Alot has been said about the table part of a vacuum system, but can't find much about the plumbing. I already have the 2 Fein III and plan on cutting mostly sheets for cabinet parts. I understand the actual plumbing part, just curious, how many zones, placement of zones... I was planning on doing a 4 zone, but got to thinking(maybe thats my problem), 8 zone 24 X 24, 6 zone 32 X 24... I keep thinking back to what Bill P said at the Midwest Camp, "keep it simple". I would just like to do it right the first time, for once.
Thanks,
Terry

[GlenP]

Hey Terry. My new PRS is shipping out either today or tommorrow. I plan on using a table design similar to the one that David Bushsbaum has on his machine. You can read about it by going to the shopbot home page and then go to David's sandbox. What machine do you have?

[bill_lumley]

Terry , my application is also cabinet parts and I find 4 zone is plenty . I had one botter tell me he was going from a 12 zone system to a 4 zone system . I only use the smaller areas for cutting partial sheets and they never match the zone profile anyway . Remember you can just keep a few scraps of laminate or other material around to cover over any zone area that is not covered by your sheet .

We all tend to overthink some of this stuff . I gazed at my navel for a long time before building my vacuum table and afterwards thought ..that was easy but then I got some good help and ideas here . I ended up using 3 way pool valves by Jandy to reduce the amount of plumbing required .

Remember the KISS principal - Keep It Simple Stupid

[billp]

Terry,
Glen, and Bill have the right idea. If you eventually need smaller "zones" you can make dedicated jigs you drop on/off the table for the specific application. There are a lot of examples of this process scattered throughout the Forum over the last few years...

[harryball]

I use a 4 zone and drop a mask, jig or pallet over the zone when I need to work on something smaller than the zone. It works very well.

I have my plumbing setup so 2 feins can pull on a single zone... I know from experience that the holding power can be painful.

Robert

[richards]

Terry,
I use Bill P.'s approach. I have two Fein vacuums and four zones. In reality, when I use the Fein vacuums, I'm cutting 1/4-sheet, 1/2-sheet or full sheets of material. Remember that even with two Fein vacuums, you'll be pulling the same amount of mercury whether you're using little 12" X 12" zones or 48" X 96" zones. In my case that is just over 5" of mercury, or about 2-1/2 lbs per square inch, so little zones don't have enough surface area to generate much holding force. Of course, I'm writing about holding down MDF, plywood, particle board and Melamine, which I cut agressively. If I were V-carving with light cuts or cutting foam, then small zones might work just fine.

When I need to cut small pieces or whenever I need more than 5" of mercury, I use my GAST vacuum. That gives me 22" of mercury, or about 11 lbs. per square inch. When I use the GAST, I bolt the puck(s) to a piece of 1/4-sheet plywood so that the Fein vacuum(s) can hold the puck(s) in place and then the puck(s) hold the material being cut in place.

The pucks for the GAST system are just pieces of plastic from the scrap bin at the local plastic supplier. Whenever I drive past their store, I stop by to see what is in the scrap bin. If the scrap is at least 3/4-inch thick and at least 4" X 4" in size, I buy it. At $2.00 per lb. for scrap, it's one of the world's greatest bargains.