Vacuum pump vs venturi setup

[Jim Tobias]

I am still fairly new to woodturning (been doing flatwork for many years) and am interested in a vacuum chuck set up for my lathe. I have a compressor that I believe is large enough to operate a venturi system on the lathe (Quincy QT-54 (~15CFM). What are pros and cons of a separate vacuum pump vs a venturi set up? My compressor is in another room (about 25-30 feet from lathe) so noise is not an issue. Is that distance a problem with venturi setup? I have looked at the one made by Infinity Tools.....anyone use that one or suggest another if venturi is the way to go?
On the surface, the venturi setup seems simpler, but I want to get some feedback from some experienced turners that "have been there do that".

Jim

[Richard Coers]

You may not hear the compressor as objectionable, but you will have a rushing air noise where ever you mount the venturi. You have to compare to the noise of the vacuum pump. You also have to compare running a 3hp motor on the compressor vs spinning a 1/2 hp. Hose length won't make a difference. Just compare the air usage data of the venturi vs the compressor data. 15cfm is a rating that you need to know the pressure as well. The system sold by Holdfast is "Requires air compressor for use (minimum 2.5 cfm at 55-65 psi".

[David Walser]

Jim -- A venturi system can work very well. If noise from the venturi is an issue for you, you can eliminate it mounting the venturi outside your shop and running a longer vacuum hose to your lathe's headstock. Even an extra 50' of hose length will not add a lot of volume to the area from which your vacuum system needs remove air. So, with an adequate air compressor, you can have a quiet, strong, vacuum chuck system.

Having said that, I see wear and tear on your air compressor as the major potential disadvantage of using a venturi system. Vacuum pumps, generally, are designed to be run for hours on end. Some of the rotary vane Gast vacuum pumps designed for use in industry are run non-stop for weeks. These pumps are often used by woodturners. Woodturners also use vacuum pumps that are designed for use in the HVAC industry. These pumps are also designed to be run for hours at a time without hurting the pump. Most air compressors are not designed for continuous use. That is, the air compressor cycles on and off as air is drawn from its tank. By design, the compressor's pump is not supposed to run for hours on end.

Is this a big deal? For most hobby turners, I would think not. They don't use their vacuum chucks every day for hours each day. However, they might use a vacuum chuck for an hour or more at a stretch each time it is used. And, because wood 'leaks' air, the vacuum pump will need to be running virtually all that time. For a venturi system, this will require the air compressor to be on virtually all the time, too. For occasional use, that's probably fine. For every day use, a venturi system is apt to use up an air compressor fairly quickly.

You might ask, if a vacuum pump can run for hours on end without a problem, why can't an air compressor? After all, an air compressor is just a vacuum pump run in reverse. I suggest there are two reasons: First, it's a matter of design. Some air compressors are designed for continuous use. The ones most of us use in our shops are not. It costs a lot more to build a compressor that's designed for continuous than one that is not. Second, is the question of volume. Air compressors move a lot more air than do vacuum pumps. Moving that volume of air, and stuffing it into pressure tank, generates a lot of heat -- heat that the compressor needs to be able to deal with without being harmed. Also, venturi vacuum pumps are very inefficient. It may take 3 - 5 CFM of compressed air to generate 1 CFM of vacuum.

HTH

[Kevin Jenness]

As said, the venturi setups are cheaper but are far less efficient than an electric vacuum pump. You can find used Gast 0522 or 0523 1/4-1/3hp rotary vane pumps on ebay for under $200 that will work well for what you want and have no problem running continuously.

[Mitch schiffer]

I am fairly new to turning but i have been using a vacuum on most of my pieces at some point. I am still using the stock venturi setup that came with my lathe. It does work well but I am planning to switch to a vacuum pump for reduced noise and to keep from running a 5hp compressor to do a job that a 1/4hp vacuum pump can do without issue.

[Jason Edwards]

I have no affiliation with the company but this is a really good import: https://www.frugalvacuumchuck.com/pumponly.html and the owner of the company is quite knowledgeable. I agree with the others, running a vacuum pump is a lot friendlier long term solution than listening to your compressor run all the time.

[Walter Mooney]

Plus one for the Frugal system(s). I got mine at SWAT several years ago, and love it! I can have it up and running in under a minute, and it’s handled everything I’ve ‘asked’ of it.

[Gary Pennington]

Another vote for the Frugal setup. The pump is inexpensive but works well.

Gary

[Robert Hayward]

Yet another +1 for Frugal. The Frugal system is hard to beat for the money.