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  1. #1

    Join Date
    Sep 2019
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    15

    Vacuum table grid and gasket seal form

    Hello,

    I'm in the progress of making my own vacuum table.
    The grid will be milled into a sheet phenolic.

    At the moment i'm struggling with 2 points:

    1) which gasket seal to choose:

    -Round / rectangle or d shaped.

    If i use a round seal (easiest to find) would i neet to mill the groove with a ballnose bit? so the gasket matches the groove? Or can i go with a straight endmill?

    I'm building an universal table setup with 6 different zones. The contour of the zone i would seal off with the gasket.

    2) Would i mill the grid with the same endmill/ballnose bit (5 a 6mm wide) Or would i use a wider 12mm endmill for the internal grid so i have a better air displacement for the vacuum.

    Input would be appreciated!

    Adam

  2. #2
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    Nov 2012
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    989

    Re: Vacuum table grid and gasket seal form

    1. Round gaskets work perfectly fine with flat grooves.

    2. The entire table should be covered with a grid of identical grooves (matching the gasket diameter). That way you can seal off any arbitrary size and shape.

  3. #3

    Join Date
    Sep 2019
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    15

    Re: Vacuum table grid and gasket seal form

    Quote Originally Posted by CitizenOfDreams View Post
    1. Round gaskets work perfectly fine with flat grooves.

    2. The entire table should be covered with a grid of identical grooves (matching the gasket diameter). That way you can seal off any arbitrary size and shape.
    Thanks for the reply.

    Point 2 would be beneficial if i want to rearrange the zones at a later time.

    On the allstarcnc gasket site the tell to use a square seal into a square groove and a round seal into a round groove to have the maximum contact and sealing capacity.

  4. #4
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    Nov 2012
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    989

    Re: Vacuum table grid and gasket seal form

    Quote Originally Posted by DAAD View Post
    On the allstarcnc gasket site the tell to use a square seal into a square groove and a round seal into a round groove to have the maximum contact and sealing capacity.
    The part or the spoilboard will have a flat surface anyway, so I don't know how much that really matters. The machines I deal with use round gaskets without any problems - your mileage may vary. :wave:

  5. #5

    Join Date
    Sep 2019
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    15

    Re: Vacuum table grid and gasket seal form

    thanks for the input.

    I would go for a 8mm round seal. +-5/16 inch.
    What would the gasket size be you are using?

  6. #6
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    Aug 2005
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    108

    Re: Vacuum table grid and gasket seal form

    What needs to be mentioned here is that the gasket needs to project above the phenolic surface before placing the workpiece. I've used a 1/4" dia. gasket in a 1/4" wide, square bottomed slot successfully for years. The depth of the slot is typically little more than half the gasket diameter, perhaps 5/32". Once under vacuum, the gasket is compressed in the channel with contact at the sides near the top.

    Also, as a means of economy, I use random lengths of gasket longer than the cumulative gasket channel length (not cut to an exact length) for a given part with ends bedded in adjacent channel. I get my gasket here;

    https://www.mcmaster.com/foam/light-...ne-foam-cords/

  7. #7
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    Nov 2012
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    989

    Re: Vacuum table grid and gasket seal form

    Quote Originally Posted by DAAD View Post
    I would go for a 8mm round seal. +-5/16 inch.
    What would the gasket size be you are using?
    I don't have it in front of me, but it's about 8mm, or maybe 10.

  8. #8

    Join Date
    Sep 2019
    Posts
    15

    Re: Vacuum table grid and gasket seal form

    Thanks for the input!

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