View Full Version : Pump for vacuum fixture

07-03-2004, 11:51 AM
Anyone have any sources for cheap continuous work vacuum pumps? The ones we use at work run around 300-400 and pull 25-30(insert abreviation for inches of mercury here).

I don't need anything that strong, but can't seem to find anything, anywhere.

07-03-2004, 12:16 PM
Looks like ebay will be the place. Just found this http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=46548&item=3824159927&rd=1

Too bad i'm not ready to buy.:rolleyes:

07-03-2004, 04:13 PM
There's about a million & one uses for a vacuum pump and thousands of types, models, and manufacturers. Is this for a vacuum chuck? What's the chuck made of? What is the workpiece? How big are they? Need an idea of how bad this thing is going to leak. I am familiar with Welch, Leybold, Alcatel and some others--they are not for vacuum chucks. If the pump has an ultimate pressure in the micron or millitorr range it may overheat if it is pulling too much air though. Consider a screen or filter to keep the rocks out of the pump. EBay has some great deals but that little sucker in the link above probably willn't cut the mustard.

07-03-2004, 04:29 PM
It would be used for general fixturing use. Here's a link to one variation of a vacuum fixture http://www.cnczone.com/gallery/showphoto.php?photo=168&size=big&sort=1&cat=all

And if my feable mind can do the calculations correctly, 1" of mercury = roughly .5 psi. So the pump in the ebay link would put out roughly 11psi. Doesn't seem like much, but when you figure that for a part that is lets say 10 x 3, that's 30 square inches thus 330pounds of vacuum over the entire part. Is that correct, or am I an idiot.

Also the one in the picture is similar in size and shape to the ones I use at work. And no matter how large the work piece is that is held by the vacuum, if it's pulling over 20in HG, you can't move it by hand.

07-03-2004, 04:40 PM
As Steele says, this pump would be useless for a vacuum chuck. But, much more importantly, in reading the description, this pump was used for suctioning patients in a hospital. You dont even wanna know what it may have sucked out durig its life. By federal law, this pump is hazardous medical waste unless it has been sterilized and certified as clean. The still attached tubes wouldn't indicate that to be the case. The selling or offering for sale of this piece of equipment is illegal, just the same as it would be illegal to raid the dumpster at the local hospital and start selling used hypodermic needles on ebay.

07-03-2004, 09:23 PM
Ok, I give up. Why would this pump be useless.

I never thought about what could have passed through the pump. Now where are the puking 'smilies'?

07-04-2004, 07:11 AM
Hmmm ... the big router boiz assume their sacrificial MDF base sheet will bleed lots of air where the workpiece doesn't cover it. And when you make a cut that separates your parts or makes holes in them, there's more bleeding, so they rely on KILOWATTS of blower power. If you know you're not gonna penetrate the part, and if you seal off vac-table areas the workpiece doesn't cover (it's called masking tape) then you can use $20 diaphragm pumps from the pet store - no not the DOG section, the FISH section!. Just make sure the "input" is isolated cuz that's your vacuum source. I use a $30 industrial version of those, mounted in a 6" PVC pipe reservoir. Runs 24/7, draws 5 silent watts (count them, f-i-v-e watts) and I properly gasket the hollow vac-table with a 1/16" polyethylene closed cell foam, punched to match the vac holes of the vac-table. Paper masking tape (on the table, under the gasket) masks the areas not on duty. Sealed system, no losses, low power, high grip. Photos a pleasure if ya want. Regards, Terrence

07-04-2004, 07:17 AM
Ooops... some guys use ex-refrigerator compressors as vac pumps. They're cute and they work, but you gotta ask yourself where in the stratosphere the CFC gas went when the compressor was decommissioned. If u wanna use an old refrig compressor, please pay a refrig mechanic to pump the CFC gas down to a cylinder. It's the law. It's also a GOOD THING TO DO. Be good. Be nice. Terrence