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  1. #1
    Join Date
    Mar 2012

    Vacuum hold down

    I have a 96"x96" Avid CNC router that I cut very large square plastic parts on (82"x82" max). We have a Becker U 2.165 vacuum pump currently on the machine with just a large 2" hole in the center of the table. I am looking to upgrade the router table to have a grid pattern and use an MDF spoilboard, treating all ten of the patterns cut areas to minimize leakage.

    The vacuum pump says it's 3mbar. Converting to inches of mercury using an online converter, I only get 0.09 inHg. That's like, zero vacuum. I swear the thing pulls way more vacuum than that. Am I not figuring properly? I'm thinking about adding a vacuum gauge so I can see what it's actually pulling.

    I'm trying to figure out if this vacuum pump is adequate to hold down my large parts using the above mentioned strategy. Can anyone help me figure out if it's enough before I go through the process of actually just trying it?


  2. #2
    Join Date
    Aug 2005

    Re: Vacuum hold down

    I believe your pump is oil lubricated? If its in good running condition, it should pull close to 29" HG intake capped. CFM is another factor, particularly if your system is leaky. If your going to gasket your gridded and zoned bed, better seal all surfaces of the MDF. I used System 3 epoxy sealer (S2 if I remember correctly). Three coats applied on all surfaces after milling the bed flat and cutting the gasket channels. You'll have to re-mill the top surface and the channels to clean up afterward. I typically pull 26" to 27" HG on my system with that configuration with a similar pump. Buy a vacuum gage from McMaster. They're cheap at $15.

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