vacuum chuck exhaust

[Kevin Lucas]

I kept looking for an old refridgerator or A/C compressor to make a vacuum chuck system. No luck so I hit a pawn shop on the way home and they had a JB Eliminator dv-6e that does 6cfm. Yeah I know its exhaust is really odd so I need to figure a good way to make some filters to catch the oil mist. I made a rubber plug with a nipple for a line on it that seals when the cap is tightened on the handle. Any ideas on oil cathers?

[Greg Ketell]

What they use in airplanes is basically a cyclone dust collector but for oil. Use a coffee can with the air inlet coming into the side near the top pointing tangent to the inside edge, air outlet goes straight out the center-top and goes down about 3/4 of the way to the bottom of the can, then add a oil return line to the bottom of the can that drains back into your system.

GK

[Larry Marley]

MacMaster-Carr also sells filters that will capture oil mist.

[Dave Mueller]

Kevin,
I had the same problem, so I made my own filter. The first pic shows it on the pump. The small black part in the lower left is the "filter" that came on the pump. The second pic shows how it is made. The PVC parts are not exactly the ones I used, but they give you the idea. Turn the threads off the bottom PVC piece to fit in the hole on your vac pump. Use a Whirlpool Whole House Water Filter WHKF-WHSW from Lowes (item# 149007) and seal it into the PVC adapter with hotmelt glue. A two pack costs about $8. Plug the top the same way with the PVC plug. Buy a Filtrete 1900 Maximum Allergen air filter from Lowes (item #134507). It is expensive (~$19) but will stop the oil mist droplets, which are sub-micron in size. Don't substitute with a cheaper brand. Take the air filter apart and wrap the filter material around the Whirlpool water filter about three times and seal at top and bottom with PVC glue. The third pic shows the blue PVC glue sealing the top of the water filter.

The water filter stopped about half of the oil mist however with the Filtrete added, I have not seen any oil mist and have been using it for about a year.
Dave
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[Bob Bergstrom]

Great idea with the filter. I started using the high quality allergen air filter in my shop air filter system. There are about 3 times the pleats in it and when it fills up, I take it out and vacuum it. Then I just put it back in. Much more durable than the cheap ones and last much longer. I have a harbor freight pump and will have to try this filter trick. I stopped using it because of the oil mist.

[Dave Mueller]

Thanks, Bob. Just be sure to seal the top. I missed that on my first try and it smoked like a chimney. Contact me if you have any questions.
Dave

[Kevin Lucas]

That is just the idea I was looking for. I could sort of picture it in my head but I was thinking quilt batting. I knew it wasn't enough to catch the oil. I need to order some sealed bearings for the spinning adapter end as well. Not the ideal pump for this I know. As a test I had a small faceplate on plywood and a loose sheet of craft paper with a hole in it just sitting on the ply and it held a 3 or 4 inch bowl nice and tight. I know I took the hard route to do it but I cabbage stuff together more than buy it all at one go (cheapskate hehe). Thanks again guys you are life savers.

[allen thunem]

OK so I need some education on the concern or need for an exhaust filter for a vacuum pump..
what am I missing here

[David Walser]

OK so I need some education on the concern or need for an exhaust filter for a vacuum pump..
what am I missing here

Allen, it depends on the type of vacuum pump. Some vacuum pumps are oil lubricated and are designed to emit a small amount of oil in the exhaust. These pumps are frequently used to evacuate the refrigerant out of a HVAC system and the small amount of oil misted into the air doesn't cause problems. In a small shop, the oil spray can cause problems -- getting on your turning and interfering with your finish or settling on the walls and floor area where the pump is typically used and causing a sticky mess.

HTH

[Greg Ketell]

Some pumps are "dry pumps" meaning the use graphite vanes or pistons to move the air. For those, exhaust filters quiet them down and keep the graphite powder out of the shop. Other pumps are "wet pumps" where the mechanism is in an oil bath. They last longer and can build better vacuum since the oil helps to seal the mechanism. But the down side is that the output air is laced with a super fine mist of oil. If you don't catch that oil it can get on your piece ruining your chances of getting a good finish. So the idea is to build something that will catch the oil and, hopefully, let it return to the pump so you don't have to keep refilling the pump.



OK so I need some education on the concern or need for an exhaust filter for a vacuum pump..
what am I missing here

[Kevin Lucas]

It has been a bit since I posted any thing, I thought I would update the progress of the vacuum chuck. I followed Dave Mueller's suggestion for an exhuast filter with one addition. I added a line from the top. I was not sure how much air would collect in there. With no vacuum a good bit flows through and with the vacuum on very little. Some HF fittings and hardware store hose.
I made a rotary adapter out of stacked corian and a double sealed bearing. The adapter sits flat against the rear of the spindle with some craft foam added to it. A lamp rod through piece and a corian #2 morse taper threaded like the rod. No need for an extra nut at the taper end yet but it will probably need one eventually with wear. A ply round on a metal face plate with craft foam added between the face plate and ply and on front. With this set up I was getting about 27 mercury at he most depending on the seal of the bowls I tried. Next project is a drum... Thanks so much for all the help and suggestions )
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[David C. Roseman]

Congratulations, Kevin! 27 inches is a heckuva vacuum. Hope you have a bleeder valve installed for when you reverse your hollow forms. :eek:

[Greg Bender]

If you have a oil mist seperator for your air supply you can use it and they go down to fractional microns so the air should be oil free. That is what I use on mine.