Vacuum pumps

[Timothy Hoyt]

A few months ago I made a casual comment to a distant friend about how I would like to have a vacuum pump someday to use for turning. He enjoys tinkering and can rebuild anything. Well, he surprised me with a very generous offer last weekend. He e-mailed me and said I could have one the three pumps listed below.

Manufacturer	Model	Description	Link		Full text
Edwards	8 Two Stage	Vacuum Pump	https://avac.com/product/boc-edwards-vacuum-pump-40-22607-02-e2m8-rebuilt/?gclid=Cj0KCQiAy 9msBhD0ARIsANbk0A-vYEie87xhal84XQibjmVxHtQPrfPTngbsJOz7rJc9bEBxenFgzXIaAgzEEALw_wcB		Edwards 8 Two Stage Vacuum Pump
Optronic Laboratories	OL 700-86VP	Vacuum Pump	https://optroniclabs.com/products/		Optronic Laboratories OL 700-86VP Vacuum Pump
Welch	2561B-50	Vacuum Pump	Welch 2561B-50 WOB-L Piston Vacuum Pump – Chemtech Scientific $ Incorporated		Welch Model 2561B-50 Vacuum Pump

Now I have to get up to speed quickly as to vacuum pumps and chucking. My initial thoughts are to ask for the Edwards because of its capacities. I assume that too much pump is better than not enough (possibly "turn it down" somehow.) I do have minor concerns about the size/weight and the noise.
Anybody care to weigh in on this great problem I have? Thanks

 

[Alan Weinberg]

First one uses oil and weighs 50 lbs, can’t find info re the second. Last one, Welch, seems pretty good, half that weight. Hopefully one of the engineers here will opine. Lucky you.

 

[Richard Coers]

CFM is really a mute consideration. It takes very little flow to empty a hose and a vacuum chuck. If you need high flow to compensate for a leak you have a major safety issue and I don't recommend turning like that.

 

[William Rogers]

Look at Furgal. He sells a lot of pumps. He used to sell the Thomas (oil less), but his supply of Thomas dried up. I have a Thomas 2660. These pump last a really long time. I was using one to aerate my lake, it ran 24/7 for 4 years. I rebuild them (easy, parts on eBay), but for our uses it is very unlikely that would ever be needed. Gast makes a similar pump, but a bit more costly.

 

[Earl Recker]

If weight is not an issue, go with the Edwards. If it is, go with the Welch.

 

[JeffSmith]

Full disclosure - I’m not an engineer. Not familiar with the first option, couldn’t find info on the second. The third is a brand of rocking piston vac pump - my first pump was a Reichle-Thomas wobbly piston type pump. These have been used for decades in continuous use situations (like aerating ponds) and are proven performers. They are also simple to rebuild with parts available online. One other benefit - they run quietly. Mine is still in use on my carving stand and, after nearly twenty years of (ocaisional) use, shows no sign of giving up the ghost.
All that said, I scored a new, unused in the box surplus inventory Gast rotary vane pump 15 years ago on ebay for less than $100 that has been my go to since getting it. It seems indestructible. Both of my pumps pull max vacuum here at sealevel.
As for the first one - do some research. Not all oiled pumps are like the ones sold for servicing AC systems that put out an oil fog. Some are used in medical facilities providing continuous network duty remotely. I had a friend who used two of these beasts in a sealed cabinet outside his shop and piped both vacuum and compressed air into his shop. They were sourced through a medical supply house and both used oilled systems. I have no idea if they were noisy - his cabinet is well insulated and outside the rear of his shop.

 

[hockenbery]

Dave Lancaster has a pretty good article in winter 1998 American Woodturner.

He recommends a minimum of 3cfm. Most wood will leak air - usually at way less than 3cfm.
May have a leak in the plumbing but these are usually non-existent.
You might have a small leak at the seal but this is pretty rare because a seal leak is usually too big to hold.
But seals get damaged and at the end of their useful life plus a couple more turnings they may leak a tiny bit.
But wood leaks and in severe cases you need to cover the piece with stretch wrap to stop the air leakage.

 

[Clifton C]

When I pulled up the specs on the Welch 2561B The max vac was stated as 5 torr. The online converter calculators calculate that to be about .1968 inches of mercury.
That seems like almost no vacuum at all, so I'm either reading the max vac wrong, or using the wrong converter.
Could someone else do a fact check? I'd hate for Tim to get a vacuum system that doesn't suck...

 

[Randy Heinemann]

Based on the research I did before buying a system from Frugal, the vacuum pump required for a vauum chuck only needs to be capable of 2.5 - 3.0 cfm. As long as it will do that I would guess any pump would work. Oilless is nice because it's less trouble. If you plan to use the vacuum pump for other woodworking, like a vacuum press, then you might need something different but, even for that I would imagine something capable of 2.5 - 3.0 cfm would be sufficient. If you get a pump that pulls too much it's important to be able to control the flow or you can collapse a bowl or hollow form due to too much suction.

 

[Timothy Hoyt]

Well, I pulled the trigger and chose the Edwards. I am very excited to hopefully get it in the next several weeks. Thanks everyone for their help!

 

[Tom Gall]

Well, I pulled the trigger and chose the Edwards. I am very excited to hopefully get it in the next several weeks. Thanks everyone for their help!

I hope your friend's 'generous offer' is a lot less than $1,649. That said, you'll love vacuum chucking. I've been using vacuum since 1994.

 

[Alan Weinberg]

curious to what went into your decision.

 

[Bill Blasic]

Wow, those pumps at the top are not cheap! When I started looking for pumps I found the Gast Vane pumps at ridiculous prices and bought 3 or 4. But being 220 volt I was slow to use them (so they all sit in cupboards still). One of our club members lived next door to a guy who owned a store that sold refrigerators and humidifiers and he I think took in old ones and removed the gas. Well he ended up with these vacuum pumps (oil) and he gave them to our member who in turn passed them on. I took all he could get. the first system I made using that pump I still use today and still pull 27/28 (that's at least 20 years). I made a bunch for club members and they donated about $39 to the club. The only thing they had to do was get a mayonnaise jar and run a tube into it from the pump exhaust (I put a little insulation in it to catch any oil)., After 20 years there is no visible oil in my jar. At the prices quoted at the top I feel like I cheated