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Thread: New Vacuum table set up

  1. #1
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    May 2009
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    Default New Vacuum table set up

    Hoping to gain some knowledge on my new vacuum table set up.

    I decided to go with a dedicated vacuum grid table consisting of MDF top with .25" channels, and 4 ports. Using Gary's KISS table setup idea, I have the 4 lighthouse motors mounted directly to the bottom of the table with no manifolds. Each motor is switched. I have sealed the MDF table surface with 4 coats of diluted glue mix. When routing, I place a 1/4" sheet of ultralight MDF on top of the vacuum grid as a spoilboard, with gasket material in between. I then tape off the sides of the ULMDF to reduce leakage. Using my last 2 lighthouse motor setup(W/ manifold) as a reference, I am not getting near enough suction out of this set up.

    With that being said, do I need to create a larger volume of air to keep a steady pull on the sheet? At this point the only stored air space is the .25" channels that make up the vacuum table. Thoughts on this?
    Thanks,
    Marc

  2. #2
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    Sep 2006
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    cnc routing, portland or
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    well usually you glue the spoil board down. so most likely your getting too much leakage between the sheet and the grid. I use 1" ultralight I cut it in quarters to make life easy and glue it down. I also seal the edges on the inside of the quarters to isolate the zones better and makes it easier to glue on.
    you also need to shave the face off each side with 1/4" ,material that does not leave you much left and I doubt it will stay flat. the big guys can get away with a removable spoil board but not us it is just going to curl on you.

  3. #3
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    May 2015
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    SF bay area, CA
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    To use a universal vacuum with the gasket setup you'll need to screw/bolt the bleeder board down to the vacuum grid otherwise you wont get a good seal. The bleeder wont pull tight against the grid by itself since air can flow through it. I'm planing on upgrading mine the future to where my vacuum grid out of pvc so that I can tap threads to have an easy, strong, and repeatable connection of bleeder to the vacuum grid using a gasket. I make a lot of specialized jigs that use direct vacuum so I don't want to be stuck all the time with a universal bleeder setup.

    PS Haven't had my coffee yet, hope that made sense :P

  4. #4
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    Timmins, Ontario, Canada
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    I have been using a plastic grid bolted to my machine with a 1/4" foam gasket sitting in a groove around the perimeter. I use a 3/4" MDF bleeder/spoilboard that is not attached at all, just pulled down by vacuum.

    It certainly does pull down very tight, even though the air is passing through it. If you place another sheet of MDF on top of the bleeder, air pulls through that as well, but you can cut parts from it without anything moving.

    I guess it might depend upon the volume of air, but for universal youre going to need a decent amount of air anyhow.

  5. #5
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    Quote Originally Posted by marcrunner View Post
    Hoping to gain some knowledge on my new vacuum table set up.

    I decided to go with a dedicated vacuum grid table consisting of MDF top with .25" channels, and 4 ports. Using Gary's KISS table setup idea, I have the 4 lighthouse motors mounted directly to the bottom of the table with no manifolds. Each motor is switched. I have sealed the MDF table surface with 4 coats of diluted glue mix. When routing, I place a 1/4" sheet of ultralight MDF on top of the vacuum grid as a spoilboard, with gasket material in between. I then tape off the sides of the ULMDF to reduce leakage. Using my last 2 lighthouse motor setup(W/ manifold) as a reference, I am not getting near enough suction out of this set up.

    With that being said, do I need to create a larger volume of air to keep a steady pull on the sheet? At this point the only stored air space is the .25" channels that make up the vacuum table. Thoughts on this?
    Thanks,
    Marc
    Marc,
    On my plenum I have 1/2" grooves, 3/8" deep, separated by 1/2" lands. Can you go bigger than 1/4" grooves? To allow more air flow?

  6. #6
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    Portland, OR
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  7. #7
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    Well shoot,
    Here is what I have so far. Base size of the bed is 52"x97" with T track located in between the vacuum grids, as I often only need a small portion of my table with out vacuum to accomplish many of my jobs.

    At this point, I am at a loss for ideas if I want to be able to process both full sheets, as well as remove the full sheet spoilboard to route smaller jobs with T track hold down.

    With my previous set up, I used Brady's removable full sheet vacuum grid with gasketing. I would place the full sheet vacuum grid onto the table, and 2 motors would hold things down well. With this set up, I am essentially doing the same thing in reverse but have added 2 additional motors. Why the difference? Do these motors need a larger volume of air(ie, manifold/black box) than my smallish vacuum channels are able to produce?

  8. #8
    Join Date
    May 2015
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    SF bay area, CA
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    36

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    Marc,
    I have the same dilemma and here's what I've come up with...maybe

    -3/8 stress relieved pvc bolted to frame
    -3/8 stress relieved pvc glued to previous layer, then surfaced with a vacuum grid cut in and drilled + tapped holes for removable options below (You could add T-tracks in this layer flush to the vacuum grid)
    -1/4 table sized boards based on job that can be screwed to pvc such as mdf bleeder board, pvc or jigs

    I haven't had the time or money yet to do this setup, but in my head it makes sense.

  9. #9
    Join Date
    Jul 2014
    Location
    Bell, Florida
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    409

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    Quote Originally Posted by marcrunner View Post
    Hoping to gain some knowledge on my new vacuum table set up.

    I decided to go with a dedicated vacuum grid table consisting of MDF top with .25" channels, and 4 ports. Using Gary's KISS table setup idea, I have the 4 lighthouse motors mounted directly to the bottom of the table with no manifolds. Each motor is switched. I have sealed the MDF table surface with 4 coats of diluted glue mix. When routing, I place a 1/4" sheet of ultralight MDF on top of the vacuum grid as a spoilboard, with gasket material in between. I then tape off the sides of the ULMDF to reduce leakage. Using my last 2 lighthouse motor setup(W/ manifold) as a reference, I am not getting near enough suction out of this set up.

    With that being said, do I need to create a larger volume of air to keep a steady pull on the sheet? At this point the only stored air space is the .25" channels that make up the vacuum table. Thoughts on this?
    Thanks,
    Marc
    I have found the ultra lite mdf will allow lots of air to pass through and I am using 3/4" so I think you are loosing to much through the spoil - try placing a sheet of plastic over it and see how well you pull a vacuum - also you will loose a lot between zones if you do not seal between them
    Tim Lucas Custom Woodworks
    www.TLCW.us

  10. #10
    Join Date
    May 2009
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    Portland, OR
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    Yes,
    Maybe a bit more trial and error is in need. Tim, I think you are right, next is to place a non breathable layer in place of the spoilboard to see how much vacuum I am actually pulling. I am still at a loss as to why the dedicated vacuum sheet is any different than my last set up where the vacuum grid was a removable flipped sheet with gasketting placed onto the table.

    Also not opposed to the idea of making quarter sheets that are then screwed to the table.

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