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Thread: Vacuum Table

  1. #11
    Join Date
    Jul 2011
    Location
    Timmins, Ontario, Canada
    Posts
    1,825

    Default

    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.

  2. #12
    Join Date
    May 2014
    Location
    MA
    Posts
    462

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    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?

  3. #13
    Join Date
    Jul 2011
    Location
    Timmins, Ontario, Canada
    Posts
    1,825

    Default

    Quote Originally Posted by EricSchimel View Post
    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.

  4. #14
    Join Date
    Jun 2001
    Location
    Austin, TX
    Posts
    403

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    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.

  5. #15
    Join Date
    Oct 2010
    Location
    TX
    Posts
    711

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    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

  6. #16
    Join Date
    Jun 2001
    Location
    Austin, TX
    Posts
    403

    Default

    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.

  7. #17
    Join Date
    Jun 2004
    Location
    Springfield Mo
    Posts
    812

    Default vac table

    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.

    Attached Images Attached Images
    The decimal point seems to be the most important on the z axis... x & y not so much....
    ShopBot... Where even the scraps and things you mess up and throw away are cool....

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