vacuum chuck help -- will this pump work

[David Wadstrup]

I have yet another plea for help. I wrote earlier asking for advice/suggestions/recommendations on Oneway's Mega Jaws. Many who replied suggested going the vacuum chuck route instead. Which, of course, I'm now considering. I happen to have a vacuum pump made by Festool for their vacuum clamp system(VAC-SYS,) and am wondering whether it would be suitable? Here are the specs:

Technical data

Vacuum pump	VAC PMP
Volume flow (air) max.	124 cu.ft./h (3.5 m3/h)
Current	2.5 A
End pressure abs.	150 mbar
Motor speed	3300 rpm
Ambient temperature range	41°F-104°F(5-40°C)
Ambient pressure	Atmospheric pressure
Weight	20.4 lb (9.25 kg)

I'd use Oneway's chucks and adaptors, but am hoping this pump will suffice. Can anyone tell me whether it has the correct, safe pumping capacity?

Thanks again!

[ChrisA Edwards]

I just sold my Oneway 1224 yesterday. I had the Oneway vacuum adaptor on the spindle end, mounted permanently and used a Holdfast vacuum chuck.

I used a cheap AC vacuum pump ($49) from Amazon. It worked very well.

As long as your Festool can hold a pretty constant vacuum, which I have little doubt that it does, I don't think you'll have any issue.

But at least you know there are cheap alternatives available.

[David Wadstrup]

Thanks, Chris. Is that a Robinaire pump?

I had a real tough time deciding between Oneway's 1224 and 1640. I opted for the 1640 which will hopefully reach me in the next month or so. Congratulations on the sale and on the new lathe!

[ChrisA Edwards]

The brand is Arksen 3CFM. If got good positive reviews on Amazon, so for $49, I figured I'd give it a try.

It looks like the RobinAire and probably came from the same factory as it seems there are many knock offs or clones of the RobinAire.

https://www.amazon.com/dp/B00BXMRP4I/ref=dp_cerb_1

[Keith Buxton]

here are the spec on the one I got and works fine it is Thomas 2660


RANGE TECHNICAL OVERVIEW:
Max Flow 4.6 cfm / 130 l/min
Max Vacuum 27.1 in.Hg / -920 mbar

[David Wadstrup]

Thanks, Keith.

All of these different standards of measurement are very confusing. I'm still not entirely sure I'm converting correctly, but it seems like the pump I have will not work. It's a very nice German made pump, but it look to be really underpowered as it specs only 2.06 CFM and 150 mbar.

Thanks for you help, everyone.

[Paul Williams]

I suspect the amount of leaks in your system and the connection between your chuck and the wood have a lot more to do with your success than the cfm rating. If you already own the pump I would try it.

[ChrisA Edwards]

Once you get a good seal and the vacuum is established, you need very little CFM. The higher CFM rating just allows for more leaks.

I had a bowl that weighed about 2lbs and was 11" in diameter, as I mount it on the vacuum chuck, I actually open the bleed valve to allow me to position/center the piece, it'll still hold with the bleed valve partially open, but I can slide the piece on the chuck, then as soon as I close the valve full vacuum is established and it's on solid.

[William C Rogers]

Well, unless I have this wrong a 150mb is only 5 inhg. It won’t hold anything enough for turning. I have the Thomas 2660. I actually have 3 of them. One is used on the lathe, one is used for lake aeration, and the third one I rebuild and replace the lake pump. That pump runs 24/7 for two years and is generally about 50% of rebuilt spec when replaced. The pump I have will pull 28 inhg dead head, but usually get 20-25 inhg as wood is porous and depending on the species is how much vacuum I can get. The more cfm the better maintaining the vacuum. You need a bleed as you could crack thin parts due to too much vacuum. I have the Oneway vacuum chucks and they are very nice, I have a few special made chucks from PVC also.

[Jeffrey J Smith]

I’d be a little leery of the Festool pump. Much better to have one that’s tried and true. The cfm at 2.0 or so seems weak to me. While good leak sealing will help, I’d keep an eye on a good vac gauge while turning to make sure everything is going to stay where you put it.
The Thomas/Reichly aeration rocking piston pumps work well and can be found pretty cheap. Most of the Frugal systems I’ve seen used these. Lots of rebuild kits available - they’re an agricultural standard. Better yet, a gast rotary vane pump can be found used or as surplus/new equipment, often at good prices. I bought one brand new, excess inv/surplus for $85 a few years ago on ebay. They’re used in hospitals/dentists offices a lot and are bulletproof. I use both - the gast on the lathe, the Thomas on a carving stand. Both work very well.
If you build your own system, check out joewoodworker.com - while mostly concerned with veneering/bagging - lots of info on vac chucking as well. Veneeringsupplies.com is a good source for parts, too.

[Brice Rogers]

"The cfm at 2.0 or so seems weak to me".

I have a Thomas pump (2-1/2 or 3 cfm?) and another 1 cfm pump. They actually seem to work the same. When I'm drawing a vacuum, the real cfm is limited by the system leakage and the leakage through the wood. Both my 3 cfm pump and my 1 cfm pump can both draw about 27 inches Hg. (Why not more? Well, I'm at 1750 feet elevation - - do the math). On a PERFECT seal with zero leaks anywhere, the actual cfm of air moving into the pump should be zero. If you add some leaks, the real cfm through the pump increases. So on most items it doesn't matter a bit. When I turn off my vacuum, it takes anywhere between 10 seconds and 60 seconds for the piece to "let go". So, some leaks but not a whole lot.

But if I had a leaky sealed bearing or really porous wood, the higher cfm would help.

Leaky wood? Once I was sanding a bowl of Jacarunda wood and used compressed air to blow out the inside. I saw dust flying off of the outside at the same time. Jacarunda is really porous. I think that red oak is similar.

My suggestion is just "try it". If it works. Fine. If it doesn't work, then get a higher CFM pump.

[Keith Outten]

[roger wiegand]

Same question, different pump. I'll tag onto this thread instead of starting a new one. I bought an unused vacuum veneering setup at an estate sale and thought I would use the Gast pump that came with it for vacuum chucking on the lathe. I plugged the pump in today and thought it was pretty anemic. When I looked up the spec it was only 0.5 cfm . That might be adequate for a well sealed vacuum veneering bag, but based on all my reading here and elsewhere it sounds like I'm SOL with respect to vacuum chucking and need to look for a bigger pump. I don't' yet have all the other components for a system so I can't test it yet, but is there any way this could work?

I suspect I know the answer, but I'm still in denial.