Gast pumps

[Jake Helmboldt]

Looking at Gast vacuum pumps on ebay the prices are all over the place for seemingly similar models (e.g. Gast 522 with varying subsequent numbers). What gives? And what is a reasonable price to pay?

Also, I see some oilless models; should those be avoided? The last thing I want to do is think I got a deal only to find I got something useless for a vacumm chuck. That would suck (or not).;)

thanks, Jake

[Tim Rinehart]

As I understand, the oil type models may have more reliability for some extreme applications, but for us, the oilless is way to go. That avoids venting out of 'oiled' air, that can be a mess...again, as I understand from reading around.

Prices for new equipment is pretty high, and some price used not far off. What I would consider reasonable, from buying 2 (1 as backup) over the past year, is that a 522 or 523 model with 220V power source, used, should not be more than about $75 to find if keeping eyes open. I got one of mine from an outfit called Surplus Center, and I think I paid about $60-65 for it...but their stock is not steady...think "Big Lots", and it was used, but works great.

Getting similar model in 120V is more expensive from what I've seen, I guess the 220V models are just harder to sell because of voltage not being as easy for some to deal with.

Keep eye out on Surplus Center, they currently have a 4 CFM 115 VAC 0.43 HP VACUUM PUMP, a 522 series but needs a start capacitor, run capacitor and start relay. Perhaps these items can be had pretty cheap and if you know someone to help wire them up, the pump looks like a good deal, and is 120V.

Good luck.

[bob svoboda]

I agree with Tim re: oil vs oilless. I found a 120v model on the Bay for 75 + 15 shipping. It works perfectly and looks brand new. Good Luck.

[Michael Ginsberg]

I just wanted to mention (as I did the other day on my post), I recently purchased a Schuco pump and a backup as well off of ebay. It works very well for me. It holds my platters and bowls steady and quickly. You can get these aspiration vac pumps CHEAP! Good luck.
Michael

[Frank Van Atta]

Prices for everything are all over the map on eBay. Since things - and sellers - aren't all equal, getting the best deal takes some research.

[Andrew Kertesz]

As far as oil versus oil-less, you can buy filters at HF for the exhaust and the oil models are usually quiter. Someone also told me that it is not really the vacuum that counts but the volume it can move. I bought a small one and had to send it back it just didn't work.

[Mike Peace]

I got a Gast 523 incl shipping for $91 about a year ago. I was outbid for two that went for a few dollars less and one sold the next week by the same guy for about $75. All were 110v.

[Ryan Baker]

From someone who owns both oil and oilless pumps, believe me that oilless is what you want.

20-25 inches vacuum and about 4CFM is about right for turning use. More of either is better but not really necessary.

[Phil Powell]

Four years ago I bought a Gast pump off of ebay. It runs on 110 and I payed
$65 for it. Runs great, hold 22 inches of vacuum which is way more then
enough unless you're turning bowling balls and then that maybe enough. While
on the subject of vacuum stuff take a look at what's available at JT Turning.
They have some great parts. Beautifully made things.

[Tim Rinehart]

If you plan on making your own chucks and any other parts of this system, start doing that while you're keeping an eye out for a good deal on the pump.

I've found that the chucks alone, which I made from MDF, PVC Sch 40 pipe and connectors, some epoxy and tapped with Beal spindle taps (about $20 one time purchase) work very good to just bring the piece up and tape in place, with no vacuum at all.

If I were to do this in stages, it would be ...

- Make the chucks (or buy what you think you don't want to make)
- Buy a tailstock chuck adapter http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=packard&Category_Code=lathes-acc-tlstkadp This will allow you to accurately place your piece against the vacuum chuck, with or without use of vacuum.
- Build your gage and valve panel for the vacuum, as well as the vacuum adapter to get the vacuum to the lathe while spinning. Lots of threads on this and if you need, PM me and I can help you get started also on an inexpensive option, depending on your lathe.
- Keep looking for pump...

Until you get the pump, use the system as someone with a pump would, but just tape down the piece to the chuck, depending on type of piece you're doing. Will this work for anything you would vacuum chuck...of course not, but it will for alot of things.

Have fun, above all else.

[Jake Helmboldt]

Tim, thanks for the advice. I suffer from "paralysis by analysis", so I won't jump into anything.:rolleyes:

I was actually thinking about making some vac chucks, so I think I'll take your advice and start getting everything together. Plus I'm working with a machinist friend to build an outboard rest so maybe I'll get him to fabricate an adapter while I'm at it.

On another note; I see lots of references to both CFM and inches Hg. I assume both are important. For instance, some of the Gast specs indicate pumps that will pull adequate pressure (28 inches), but only around 1 CFM. I assume I need to find a pump that pulls about 25 inches AND moves about 4 CFM?

thanks for all the replies. JH

[Tim Rinehart]

I see lots of references to both CFM and inches Hg. I assume both are important. For instance, some of the Gast specs indicate pumps that will pull adequate pressure (28 inches), but only around 1 CFM. I assume I need to find a pump that pulls about 25 inches AND moves about 4 CFM?

thanks for all the replies. JH
The CFM component is what provides ability to tolerate less than perfect sealing of all the leaks thru fittings, chuck, gaskets, and the wood itself. Seems that the average recommendation has been in 3-5 CFM range, with the 0522/0523 series GAST pumps providing within that range. Some pumps for HVAC applications don't have need for high CFM, so unless you have a very tight system, you could run into issues...though many have no problems with even 1 CFM ratings. (personally...try to stay in that 3-5 range. Anything more is likely overkill..but won't hurt you)

The Hg component is the inches of mercury pull on the bowl or vessel. You want to be able to pull minimum of about 20" for most stuff, perhaps more for smaller chucks where the surface area is small, which means less total force pulling on piece to hold it in place. Can't imagine needing more than about 25", and you certainly want ability to regulate that a bit with a bleed valve, as most systems get set up for, so you don't implode a vessel into the chuck!!

Do a web search for "basics of vacuum chucks" and you'll find a good article (short) from Woodturners.org, a 1996 article.