Vacuum Generator vs. Vacuum Pump Systems

[Ned Ladner]

I've read through numerous threads about vacuum chucking systems, including those operating with vacuum generators such as the Holdfast, and those powered by vacuum pumps such as those manufactured by Gast.

i would like to get the pros and cons of both systems based upon experience and, thoughts on how the two systems compare to each other as related to performance, reliability and cost.

Thanks in advance for your comments.

[Josh Bowman]

I have a gast pump and its upside is....uh........ well, it's not small, it's not quite, it is self contained, but I do like it. We use lots of venturis/air ejectors (vacuum generators) at work, they are noisy and hog air. I can't speak to the type that oneway sells, but it has to have some noise and has to have an air supply that meets its SCFM requirements. These vacuum generators can't produce the same total vacuum that a pump can, but really you only need 17" Hg to hold a piece of wood on a decent size chuck. Generally the venturis draw down faster than a pump, but only go so far. The nicest thing about the venturis is no moving parts! If you're starting new and have a decent air compressor, the verturi (vacuum generator) might be the way to go. I know John Keeton has one and seems to like it the last I heard.

[Roger Chandler]

I have the Holdfast as well........I like it because it was economical and it was ready to set up which was a simple process and came as a system.......I did not have to gather all the parts, assemble and hope for success.........the compressor I already had and that was a big consideration........

It does a good job and noise only comes from the compressor coming on and off.......which if you have a good sized one [mine is a 25 gallon, 5 hp.] then it is not too frequent.......every 10 or 15 minutes.....depending on the pourousness of the wood.......I have gotten 26 hg in vacuum on a few woods [denser ones].......most are around 18-22 hg .......adequate for my uses so far.

[Jeffrey J Smith]

I've got a Gast pump on my system, I find that it works great. My experience is a little different from what I've seen in some of the posts. I've got mine in a semi-enclosed section of the rolling cabinet that holds my grinder, and I can hardly hear it run. It draws down quickly and, with a good size chuck, can easily peg my gauge on the woods I normally turn.

The only drawback to a quiet pump is that, in the event that the thermocouple kicks in on a particularly hot day, without a reserve tank in the system, you can find your lathe turned into a launch site (don't ask how I discovered that). With either a generator or a pump, I'd recommend a reserve tank in the system.

[Thom Sturgill]

I started with a Holdfast on a Jet 1220. Did not like the through the head adapter and I was using a pancake compressor (all I has at the time) located in the lathe base. NOISY!!!
When I bought my Jet 1642 I had it in the back room of the rental house I was in - the small lathe was in my daughters garage across the street. I set up a vacuum pump and bought one of JTs adapters - much better than the through the head version. The dedicated pump (not a GAST) is small and quiet. I could run it without disturbing others in the house. Now I have a large shop and large compressor so the Holdfast with the better adapter would work fine, but I still use the small pump on the large lathe with the Holdfast dedicated to the small lathe. Maybe I'm just too lazy to reconfigure a working setup.

[John Keeton]

As Josh noted, I do have the Holdfast system and it does a great job. It is compact, simple, no maintenance, costs less than the pump system, and sets up quickly. I store it in a cabinet, though one could leave it in place. Personally, I don't like having extra "stuff" on the lathe all the time. I easily draw 23" on good wood. The Holdfast chucks do a good job, as well. However, unless they have redesigned them, you will want to "ease" the sharp edges on either side of the foam seal to avoid marking the piece.

[Fred Belknap]

John I was having the same problem with the hard plastic marking my turnings. I covered the foam rings in the vacuum chuck with some stick on foam from Walmart and it has worked fine. Mine will draw about the same as yours on good wood but most of the time a little less. I still use the tail stock as long as I can. I leave mine hooked up on the wall beside the lathe, it just takes a minute to attach to the lathe. I have used it a lot and it has done the job.

[Jim Burr]

I'm heading to the Holdfast...I'm not an engineer sopre-made is best! I've been using a refrigerator compressor picked up for $40.In my stabilizing tank, it pulls -28-30" mg...that discussion has alreadytaken place. I'm having a lash with that and a bleed valve to hold more in the15-20 range. It’s not fast, but neither am I!