Reply with QuoteTook a quick look at the manual. No mention of duty cycle. I would be concerned that the motor would overheat in a vacuum table system.
Cheap vacuum pump any good?
I was wondering if somebody tried the vacuum pumps that Harborfreight is selling for A/C purposes to use for vacuum tables? Might work but the specs are a bit unclear. I guess the vacuum pressure is more than sufficient but I am not sure if the flow rate is enough for practical work. 2.5 cfm does not sound like much.
Any opinion? Thanks....
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Took a quick look at the manual. No mention of duty cycle. I would be concerned that the motor would overheat in a vacuum table system.
According to the specs it can only pull 0.003"hg which seems extremely low.. I know shopvacs can pull at least 5"hg.
If you want a decent pump that move 5cfm and pull 25"hg then take a look at ebay for the thomas pumps. there used to be several on there for $30-70. I have been using 3 of them for the past 3 years, sometimes over 8H of running with no problems. With 3 pumps I can hold down most anything on my 24"x48" table.
That is what I find unclear but I believe the 10Pa vacuum spec is "absolute" pressure which would be over 29" of mercury vacuum but I am not sure. If such a pump is supposed to dry out refrigerant systems it needs to pull a very high vacuum.Originally Posted by Phife
As for the duty cycle I was wondering anyway to use an empty propane bottle as "vacuum tank" with a pressure switch so that I don't need to run the pump all the time.
I will check ebay and otherwise maybe buy the Harborfreight pump for test. If not working I just take it back.
I use a 4" PVC pipe about 36" long for my vacuum reservoir. Works just fine and you can tap the fittings into the end caps.
You will find that you are going to need the pump constantly running for vacuum hold down applications, unless you have a really good seal and non porous material that will not be cut through.
Have a look in the work hold down forum here, there is are several threads about this, and theres even one with the links to the ebay auctions, and pictures of my vacuum system.
http://www.cnczone.com/forums/work_f...m_fixture.html
Cool! Thanks for the hint. I did not even know about a specialized forum in this maze. I will check there....
This looks identical to my Chinese vac pump that I use for vacuum bagging. I can attest to the unsuitability of these units for any sort of continuous running. The pump section overheats and then oil mist starts coming out of the breather. This is a real pain for a workshop with moulds sitting aroundI'd look elsewhere for a pump to run a vacuum table.
O.K., good to know. Then I can skip that trial.
