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Using a vacuum system to hold a part

  1. Feb 19, 2008 #1
    Has anyone out there used a vacuum system as a vise? We've been tossing the idea around about suctioning a part to a table as opposed to clamping or screwing it down. This will keep the surfaces from becomming marred or dinged up.

    Any suggestions, or does anyone know of any sites or systems already doing this?

    Not sure if the Venturi pump (aspirator) would be a high enough vacuum pressure system for this or not.

    Any help would be appreciated.

    Thanks,
     
  2. jcsd
  3. Feb 19, 2008 #2

    Q_Goest

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  4. Feb 19, 2008 #3

    mgb_phys

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    You generally don't need a very high vacuum.
    Atmospheric pressure is 15psi or 1kg/cm^2 so this is the most you can achieve. But with 90% vacuum you get 90% of this force.

    As Q_Goest said it is very common. A very useful tool for small electronics is a vacuum pick, a little syringe like thing with a vacuum and a release button - it lets you pick tiny parts and put them down precisely.
     
  5. Feb 19, 2008 #4

    Danger

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    This isn't exactly the same thing, but screen printing machines (at least, the one's that I used) have vacuum holes in the table to prevent the vinyl or other substrate from sticking to the ink and being lifted with the screen after a squeegie pass. It works quite well, as long as the holes remain clear of gunk.
     
  6. Feb 19, 2008 #5
    Say I wanted to machine a block of aluminum. Rather than clamp it to a milling table, I want to turn a vacuum on and have the part withstand the friction from the cutter. I can see if being done, and I've heard of people doing things close to this, but I wasn't sure what (if any) the industry standard was...

    Ex. 6" x 6" x 2" aluminum where I want to run a quick 1/8" end mill through the center. The chip to chip time (time to machine) should be less than the amount of time it takes to set the part up and clamp it into position....
     
  7. Feb 19, 2008 #6

    mgb_phys

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    Simply picking up the Aluminium would only need 3kg or about 3cm^2 or 0.5 sq in of vacuum.
    Holding it against a cutter is a little trickier - you would have to know what sideways force the cutter is applying. Generally vacuum systems don't do that well against sideways loads. To get the vacuum to hold you want the vacuum chuck and the piece it is holding to be nice and flat and smooth - which means they tend to slide around.

    It's like when you put down a flat piece of metal onto some oil or water, it's hard to lift it straight up against the air pressure - but it's easy to slide it around.
     
  8. Feb 19, 2008 #7

    Danger

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    Have you considered a magnetic retainer? The surface grinder in my old high-school machine shop used one, and it held like crazy. For a non-magnetic material such as aluminum, you can surround it with steel stop-blocks held by the magnet.
     
  9. Feb 19, 2008 #8
    those are good ideas...I am going to look into those.

    thanks
     
  10. Apr 7, 2008 #9
    Cheep solution for vacuum clamps

    The cheepest and easiest way to do a vacuum hold down system is to do what I did. I bought clamps from a guy who has been selling them on Ebay for years. Each set is only 25 bucks which is less than what I pay for machine bits. I just ordered his double sided clamps too to try out. The single sided work perfect. Check it out. You can just search Google.com for dcad100. That is his Ebay user name.

    Good luck,
    Catch you later
     
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