Vacuum chuck filter

[Richard Dooling]

I am just finishing the assembly of a vacuum chuck and I'm using an HVAC pump because I already have one. Thanks to some comments I've read here I'm wrapping the oil port with loosely woven material to filter oil mist. I need to tighten some fittings but right now I've got 25 in.Hg so I'm pleased. The Venturi I have struggled to get to 17 in.Hg plus of course that meant relying on my very loud compressor.

I've read that some people install an inline automotive fuel filter. Am I right in assuming that this serves to filter air coming into the pump through the bleed valve?

Thanks, Richard

[Robert Hayward]

I use an automotive fuel filter for the vacuum pump intake port. The bleed valve does not have a filter on my setup. Would be easy enough and cheap enough to do though.

[Josh Molaver]

Same - I use an auto fuel filter; this one (but likely any would work). I think this is the one recommended when I got the Frugal Vacuum Chuck system.
https://www.napaonline.com/en/p/SFI23003

[Eugene Dixon]

I've got a Gast oil free vacuum pump that was formerly used to collect air samples. I used a fuel filter for awhile and had to monitor it for pluggage. So I put two in parallel and ran for awhile, but not often. Finally put a fuel filter on the bleed line and moved to a Gast type particulate filter and separate water separator.

I've got a (line?) leak of some sort. After valving off the vacuum the tank bleeds from -26" (I've got cheap0 gauges) to -5" in a couple of weeks. Of course I'm using an old AL pressure cooker with a 1/2" Lexan lid so not the best of tanks. Need to find thicker Lexan or glass for sure.

[Dwayne Watt]

I have an inexpensive ($6) inline air filter from Harbor Freight on the bleed valve side of the circuit to keep shop crud out of the valve and gage when the vacuum is released. I use a slightly better air filter between the valve and the compressor pump to assure crud stays away from the pump itself when the vacuum chuck is in use. This is on an oil-less pump system. There is also a small filter on the exhaust port of this particular pump essentially to keep contamination from entering when not running.

[Richard Dooling]

Thanks to everyone for replying!

I found a diagram in Doc Green's Fixtures and Chucks for Woodturning and he uses one fuel filter between the manifold and the pump inlet.

Robert I think this is what you have described. I guess it needs to be a good metal housing to withstand exposure to the full vacuum.

Josh, is the filter you linked to in a location that is not subject to a strong vacuum?

Eugene, I'm not familiar with Gast type filter. I Googled it and found a couple of types. Does this have a standard 1/4" NPT thread?

Dwayne, if I find that I'm using this a lot then I'll probably move over to an oil-less pump too.

Richard

[Robert Hayward]

The ideal filter will be clear so you can see if the element is dirty. I have had no problem with the clear plastic filter imploding. Here is a picture of my Frugal setup back when it was new.

[Richard Dooling]

Thanks for the picture Robert. The filter is bigger than I thought and the setup make a lot of sense for keeping everything together.

[Eugene Dixon]

Eugene, I'm not familiar with Gast type filter. I Googled it and found a couple of types. Does this have a standard 1/4" NPT thread?



The one I bought (maybe from Zoro) has 1/4" NPT threads. I'll try to remember to take a picture tomorrow.

[tom lucas]

I use one of these
https://www.veneersupplies.com/products/Inline-Vacuum-Pump-Filter-25-Micron.html

[Josh Molaver]

Here are pictures of my setup; the filters are inline on the vacuum pump (preventing anything from coming back into the pump), and also on the coarse and fine adjustment valve lines to prevent dust from coming in.

498870 498871

[Eugene Dixon]

The filters:
498884
Water separator on the left, particulate on the right.

The piping system:
498885

The pump is under the shield below the filters.

FWIW, here's the pressure cooker turned vacuum pot:

498886
The pressure reading is encouraging. I cinch the top about a 1/4 of a turn all the way around. The pump has not been on since Friday evening.

[Richard Dooling]

Again, thanks to everyone for your input!
I've decided to put a fuel filter in at the pump inlet. That will cover the line from the headstock and the bleed valve. I shouldn't get any dust from the headstock end unless I make a doughnut. That would be unfortunate if it caused a loss of vacuum and the piece went flying. I tightened up my connections and am now getting a little over 28 inHG with a piece of acrylic on the chuck. Of course real world materials may bring this figure down some.

Robert, I'm definitely going to copy your setup. I like that everything is assembled into an easily moved unit. It also will provide support between the manifold assembly, the filter and the pump.
Eugene, I played around with a vacuum pot for a while but didn't pursue it seriously. Anyhow, that's why I had the HVAC vacuum pump.

[Robert Hayward]

Robert, I'm definitely going to copy your setup.
More pictures of my vac caddy so you can see both sides.

[Richard Dooling]

Thanks again Robert, I wouldn't have thought of the cord winder. Clever!

[Eugene Dixon]

Vacuum chuck doesn't work to well on red oak, OBTW.

[Brice Rogers]

On my vacuum system, I put the filter immediately before the pump. In some of these pictures I see that the filter is between the chuck and the pump but the bleed valve can suck in dusty air. How much dust? Probably not a lot. But why not place the filter just in front of the pump?

By putting it before the pump, ALL air is filtered - - both the bleed valve and the chuck air.

[Richard Dooling]

Eugene, I figure that any very porous wood is challenging and red oak is so porous that I'm thinking it would need grain filler. That might not be a desirable part of the finishing process.

Brice, that makes sense to me too. I also bought a metal body filter since I'm not comfortable with the plastic ones that are as inexpensive ($4.58) as the metal one I got.