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Thread: Planning a vacuum fixture and need help for vacuum source.

  1. #1
    Join Date
    Feb 2008
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    Miller Marine Products, Ridgefield Washington
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    876

    Default Planning a vacuum fixture and need help for vacuum source.

    I plan to make a vacuum fixture for this part (see picture)I need a vacuum source either a pump or a venturi type source. Cycle times I expect to be around 5 minutes or less. I will probably make 20 to 50 at a time. Right now I have a fixture made that uses some corner shop made clamps allowing me to drill and tap the holes in the interior,I add hold down screws through those drilled holes and cut the profile. I would like to put the blank on held by vacuum and do the whole part to get the cycle time down.

    I use vacuum on a router table but it is a high CFM low pressure system that allows a lot of air leakage. This fixture I plan to be a high hold down pressure no leakage or very low leakage system. Of course I want to get by as cheap as possible. I plan to machine the fixture specifically for this part. I have a couple Harvey "O" ring cutters and some "O" ring material. The part is cut from a 19.5" x 11.75" X .250" 5052 AL blank it has plenty of surface area for vacuum the part is bent after machining.

    I have been looking on my local CL for a vacuum pump but I don't really know what type I need other than it needs to be continuous duty. I am not sure which type are designed for continuous duty. I have heard the venturi type vacuum source use a lot of air.



    Would this work? GAST Vacuum Pump DOA-V720-AA Oil-less Diaphragm Pump Air Compressor with Vacuum | eBay
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    WWW.MillerMarineProducts.com
    Proto Trak DPM CNC Bed Mill
    Brand X Industrial router
    Sharp SVL-2416SE-M VMC

  2. #2
    Join Date
    May 2011
    Location
    ny
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    770

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    I made one from a lawnmower engine works great, trouble free for the last 6 years I pulled the camshaft put a soft spring on the intake valve Made a check valve on the spark plug hole and its good to go I have it hooked to a old 20 lb propane tank for a reservoir for good initial high volume suck down. Pulls good volume and 22-25 inches mercury.

    Video of it working
    https://vimeo.com/78819653

  3. #3
    Join Date
    Dec 2011
    Location
    Piedmont, SD
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    As an avid veneering enthusiast, I've got a venturi style, automated pump from vacupress that I've run for years. If interested in veneering as well, I'd highly recommend. Unless you're evacuating a 4'x8' press bag, they do not use much compressed air at all. Especially for your intended use - a quick shot will establish your vac hold down to 20-25 Hg in a second or less, air triggers off and silently holds your part til the next one.
    However, I'm sure they're now going for $750 to a full grand now days.

    AVOID: cheapo-vac pumps, or at least make sure it's oil free. Thought I pulled a bargain through HFT, until it completely fogged the shop with oil vapor while in use. Good grief!

    Quick search on my favorite veneer supplier revealed this:

    https://www.veneersupplies.com/produ...M-120-VAC.html

    Doesn't get much better.
    Also, check his veneer pressing supplies - awesome vac-seal tape you'll likely need around the jig, unless you mean the O-ring stuff you have is intended to be the vac seal point on your jig.

    https://www.veneersupplies.com/produ...116-x-100.html

    Okay- just meant to advise, but I guess I've done some shopping for you too...!

    Jeff

  4. #4
    Join Date
    Jun 2013
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    Pasadena, CA
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    Default

    You can look for a refurbished oil-less double piston pump on eBay like the ones made by GAST or Thompson.
    I have 2 of them and they cost about $150 each some 6 years ago. Usually I would use only one of them for a pod like you describe. Occasionally I also turn on the second pump when there is more leakage or to draw down vacuum faster.
    I recommend a few gallons vacuum reservoir to evorcome the initial laekage before the blank settles down on the gaskets.

    You may also want to look at this 1.2hp Harborfreight compressor: https://www.harborfreight.com/2-gall...sor-64596.html

    It is the same oilless double piston design as the GAST pumps, inexpensive and higher power (mine have only 1/2 hp). I am pretty sure this compressor can be reconfigured as vacuum pump as well (swapping in and outlet and eliminating the pressure switch) and you get a reservoir for free.

    As mentioned in the other post do not use the cheap air conditioner pumps the spew out a lot of oil.
    Box Joint, Dovetail, Guilloche and MazeMaker Software Here

  5. #5
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    Jan 2011
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    gleason, wi 54435
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    I will put pictures up of a pump I will be selling tomorrow night.

  6. #6
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    Feb 2008
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    Miller Marine Products, Ridgefield Washington
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    Thanks for the info. Bob you can shoot me an email of what you have if you want to. mike@millermarineproducts.com
    WWW.MillerMarineProducts.com
    Proto Trak DPM CNC Bed Mill
    Brand X Industrial router
    Sharp SVL-2416SE-M VMC

  7. #7
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    gleason, wi 54435
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    Mike are you planning to vacuum 20-50 and run them in one run or is 20-50 at each run but 1 at a time? It makes a big difference what vacuum pump is appropriate.

  8. #8
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    Feb 2008
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    Miller Marine Products, Ridgefield Washington
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    Quote Originally Posted by bobmoore View Post
    Mike are you planning to vacuum 20-50 and run them in one run or is 20-50 at each run but 1 at a time? It makes a big difference what vacuum pump is appropriate.
    These parts are one at a time made in my VMC 50 part runs. I have been making them on my router table 20 at a time but edge finish is not great and my shop built vacuum system is not really up to the job I have probably made 200 with the router over the last year. I changed the design slightly and added taped holes. I was spending way too much time sanding the edges of the parts. The VMC cuts much nicer and faster.

    Thanks Mike
    WWW.MillerMarineProducts.com
    Proto Trak DPM CNC Bed Mill
    Brand X Industrial router
    Sharp SVL-2416SE-M VMC

  9. #9
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    One more thing comes to mind. Depending on the bit, feed rate and depth, the forces on the blank will be substantial. While an o-ring cord in a groove can seal the vacuum well (given proper compression), it will not hold major horizontal forces and the slippery aluminum on e.g. a wood or plastic fixture will also tend to move. You could use a thin adhesive compressible gasket foam tape that will hold vacuum and horizontal force or add some other non-slip material to the fixture surface.
    Box Joint, Dovetail, Guilloche and MazeMaker Software Here

  10. #10
    Join Date
    Dec 2007
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    2,283

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    Quote Originally Posted by Burkhardt View Post
    One more thing comes to mind. Depending on the bit, feed rate and depth, the forces on the blank will be substantial. While an o-ring cord in a groove can seal the vacuum well (given proper compression), it will not hold major horizontal forces and the slippery aluminum on e.g. a wood or plastic fixture will also tend to move. You could use a thin adhesive compressible gasket foam tape that will hold vacuum and horizontal force or add some other non-slip material to the fixture surface.
    We use pods that are just a custom fixture to machine parts on our Pod and Rail cnc that has way more force then a shopbot.

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