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Vacuum pump question

Chris Rauber

Chris Rauber

Joined
Sep 30, 2021
Messages
44
Likes
11
Location
Canisteo, NY
I paid $40 for four vacuum pumps at an auction. Does anyone have any good knowledge or recommendations of places to begin to figure out these pumps?

pumps1.jpg


Hoping to turn one of them into a vacuum chuck pump.
 
Last edited by a moderator:
It appears three are Thompson pumps and the other one is a Gast. I am not familiar with that Gast. I use the Thompson pump for my vacuum chuck. You will need to get a capacitor for the Thompson. They are very easy to rebuild and you can get the kits off the bidding forum. Once rebuilt (if necessary) they will last a very long time. I have three, two I rotate for my lake and one for my lathe. The lake pumps run 24/7 for about three years before I rebuild it. I’ll get the capacitor size later if someone else doesn’t provide then information. You did good.

Edit: You also will want to put some isolators on the feet.
 
Wow! I paid $100 a few years ago on eBay for one Thompson pump like yours. It had previously been used as a goat milker. It’s been wonderfully dependable for me as part of a vacuum chuck setup. If it were me, I’d keep two (one for a spare) and sell two to finance some tools. Good luck!
 
To save yourself some time, read the labels on them carefully and/or look them up online. 1 (or 3) may have the capacity to work in a vacuum chucking situation and the others will not. Don't waste your time on the ones that will never get the job done. Any of them should be able to pull the minimum negative pressure, likely after a rebuild, though you might get lucky. The other big requirement is the minimum amount of air drawn. You probably need at least 3 cfm to manage inherent leaks in the wood and system. If the pump is rated at 1.2 cfm, it may work fine for some purposes, but it won't have what you need to hold a big bowl on your lathe.
 
Google is your friend - and Dean had some good advice. Look up the specs. Ebay also is a source for rebuild kits. The Thomas pump is very similar to a rocking piston pump I bought on Ebay several years ago. It had been used as an aeration pump in a pond or lake of some kind. I used it for vacuum chucking on a jet 1642 (worked fine), but only use it on a carving stand now. It got retired when a larger lathe entered the shop.
A lot of these pumps are used for continuous duty apps so rebuild kits are pretty common and often restore to near original specs.
 
I have one of the Gast like yours. Paid $70 as I recall at an auction. The guy who used to own it used it to draw down AC systems in RVs. It was from an area hospital from the 70’s and used for suction. I believe it was called a wet ring or wet gear vacuum pump. Doesn’t pull quite the full vacuum for my location that my larger Robinair does, but close and is phenomenally quite compared to the sliding vane type. No smoky discharge either. They are very low maintenance and designed to run continuously for long periods of time. Found all the info on the internet.
 
Here is the cap I have on my Thompson pump. These pumps have been around a long time. I became familiar with them in the mid 1980s. They haven’t change a lot. They are well suited for vacuum chucking and have around 4 cfm. Mine consistently pulls 25 in. hg.

IMG_1686.jpeg
 
William Rogers said:
It appears three are Thompson pumps and the other one is a Gast. I am not familiar with that Gast. I use the Thompson pump for my vacuum chuck. You will need to get a capacitor for the Thompson. They are very easy to rebuild and you can get the kits off the bidding forum. Once rebuilt (if necessary) they will last a very long time. I have three, two I rotate for my lake and one for my lathe. The lake pumps run 24/7 for about three years before I rebuild it. I’ll get the capacitor size later if someone else doesn’t provide then information. You did good.

Edit: You also will want to put some isolators on the feet.
Click to expand...
I wonder if I can find a similar model and use a kit for that, I have 3 of the 2618 models and they seem scarce for some reason both for parts and information. I found a rebuild kit for my model that’s 367 dollars, which seems steep but maybe I’m just cheap. I’ll try to find more info on the capacitor and good info on the feet! Thank you
 
Lou Jacobs said:
Wow! I paid $100 a few years ago on eBay for one Thompson pump like yours. It had previously been used as a goat milker. It’s been wonderfully dependable for me as part of a vacuum chuck setup. If it were me, I’d keep two (one for a spare) and sell two to finance some tools. Good luck!
Click to expand...
Now to just find an appropriate service kit for my model #. They seem hard to get your hands on
 
Dean Center said:
To save yourself some time, read the labels on them carefully and/or look them up online. 1 (or 3) may have the capacity to work in a vacuum chucking situation and the others will not. Don't waste your time on the ones that will never get the job done. Any of them should be able to pull the minimum negative pressure, likely after a rebuild, though you might get lucky. The other big requirement is the minimum amount of air drawn. You probably need at least 3 cfm to manage inherent leaks in the wood and system. If the pump is rated at 1.2 cfm, it may work fine for some purposes, but it won't have what you need to hold a big bowl on your lathe.
Click to expand...
Yeah it seems like the Gast might be a bit undersized for my purposes. The Thomas 2618 model is hard for me to find information on for some reason. I plan on reaching out direct to the company to see if they might be able to help. Thanks for your advice!
 
William Rogers said:
Here is the cap I have on my Thompson pump. These pumps have been around a long time. I became familiar with them in the mid 1980s. They haven’t change a lot. They are well suited for vacuum chucking and have around 4 cfm. Mine consistently pulls 25 in. hg.

View attachment 52290
Click to expand...
Thank you so much! Now I can at least get one of those coming in the mail. Now I just need to track down some seals.
 
Chris Rauber said:
Thank you so much! Now I can at least get one of those coming in the mail. Now I just need to track down some seals.
Click to expand...
Chris, I have the 2660 pump. Rebuild kit for that is $34 eBay. I was first familiar with these pumps in the 1980s used in medical oxygen concentrators. They look about the same. I am going to rebuild my lake pump later this week. I have the kit and can take measurements. The only difference that can really affect things are the cylinders and maybe the top o-ring. Fairly certain reed valves would be the same. First I would get the cap and see what the pump will do. New I get 26-27 in. hg. vacuum. Another thing to do is put a hose barb in the exhaust. This will cut the noise down by about 50%. It will be later this week before I rebuild my pump.
 
I
William Rogers said:
Chris, I have the 2660 pump. Rebuild kit for that is $34 eBay. I was first familiar with these pumps in the 1980s used in medical oxygen concentrators. They look about the same. I am going to rebuild my lake pump later this week. I have the kit and can take measurements. The only difference that can really affect things are the cylinders and maybe the top o-ring. Fairly certain reed valves would be the same. First I would get the cap and see what the pump will do. New I get 26-27 in. hg. vacuum. Another thing to do is put a hose barb in the exhaust. This will cut the noise down by about 50%. It will be later this week before I rebuild my pump.
Click to expand...
That would be great. I reached out to a vendor that seemed to have every rebuild kit under the sun and received this response:

“Parts for that model are no longer available. Even if they were they would cost more than just buying a new pump.


We have comparable models starting at $295 in our store.”

I’m now understanding how they were so cheap at auction lol
 
Chris, you might not need to rebuild the pump. Wait until you get the cap and see what the performance is first. Maybe one is a fresh rebuild (lucky). The pump is capable of pulling 27 in. hg. See if any of the three are even close. I saw the expensive kit to rebuild the 2618. It includes the crankshafts, but I never have had to replace the crankshafts for my rebuild kits.
 
I got a response from Thomas, the makers of the pump:

“
Hello
Thank you for contacting Thomas. This model is proprietary and we are unable to sell replacements or service kits.

I would recommend going back to the OEM the unit came from for replacement options.

Regards”
 
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