Thinking about building a Vac Generator

[Rick Fisher]

Anyone here built a Vac Generator for a lathe ?

I decided to build a vacuum generator for my lathe. I'll get the Oneway attachment for the hand wheel.

Never having done this before, and never having used a vac on a lathe, how do these spec's look ?

The Air-Vac MFP-M104H 2 stage vacuum motor will create 27.2HG with 6.0 CFM of flow, from 2.4 CFM of compressed air, at 75 PSI.

I have an 80 gallon x 5 hp compressor that is more than capable of keeping up.

The motor is $60.00 USD .. with a $22.00 Muffler.
http://www.air-vac-store.com/mm5/mer...egory_Code=MFP

I figure I would need a vacuum gauge and a regulator .. I could use the regulator to control the whole thing ??

The advantage over a Vac pump would be the 80 Gallon tank on the compressor. In the case of a power outage, or a tripped breaker, I would have plenty of Vacuum left to hold the work until it stopped spinning. And I have the air already..

I also think this would be far more capable than the Holdfast if I wanted to use it for Vacuum bagging, due to the volume of air this will move.

The Holdfast appears to be rated at .6 CFM of flow.. While the Oneway system is 4.5 CFM of flow.

I really think in a lathe situation.. There would be so little flow that the compressor would probably never kick on ..

Where are my flaws in this plan ?

I am thinking of building the whole thing into the lathe, with a coupler to be able to use it for other things.. So the lathe would become the Vacuum pump as well.

[Thom Sturgill]

Wood is porous. Even when sealed with sanding sealer.

I had a Holdfast connected to a pancake compressor and it ran constantly. Replaced it with a small vac pump that is so quiet I have to check to be sure its running sometimes. On the other hand 6cfm is way more than enough for even moderately porous wood I would think. I normally see 4-5 cfm as the desired value. I was able to accidently crush a bowl with the holdfast.

If I understand correctly, the venturi system requires constant airflow to maintain a vacuum unless you add a check-valve. Otherwise when the flow stops there is nothing to keep air from flowing back INTO the venturi and down the hose to the chuck. So even if the chuck + turning was sealed and the lines were sealed, you would lose vacuum.

[John Keeton]

Rick, it sounds like you are interested in doing other things with the vacuum system aside from turning, so the Holdfast system may not suffice. I have used the Holdfast for 2-3 years, though my methods of turning have changed somewhat and I don't use it as often now. It is more than sufficient and the problems Thom had with the pancake compressor are related to the storage capacity of the compressor tank. With your compressor, the Holdfast wouldn't run the compressor very often. The cost of the Holdfast generator, with gauge and regulator, is $129. Not sure this project is cost effective - unless, you want to use it for vacuum bagging, etc., as you state. Additionally, it may generate too much flow/pressure.

While there are a bunch of folks that use a vacuum system that is permanently attached to the lathe, I find the Holdfast system to be very convenient. It weighs next to nothing, and I can attach it to the lathe in a couple of minutes. For my occasional use, it is the best solution. For you, it may not work as well.

[Shawn Pachlhofer]

I would skip the Holdfast vacuum generator.

For the same or less money - you can get a true vacuum pump from Harbor Freight. For a bit more than the Holdfast - you can get a very nice Robinaire vacuum pump.

For less then $20 - you can buy a venture vacuum generator at Harbor Freight. It might need a brass fitting or two to adapt it for use, but certainly cheaper than Holdfast.


also - vacuum generators require you to hook them to an air compressor and run it almost constantly (even with an 80 gal tank). I have an upright 60G compressor. It's a LOUD piece of equipment. My HF vacuum pump is not whisper quiet - but it makes far less noise than a compressor.

[Steve Estabrooks]

i built my system from Veneer supplies, they have a lot of info on this site:

http://www.veneersupplies.com/pages/...um__Press.html
This is for a vacuum press but the principle is the same. I have had mine for a couple of years, works great

[Harry Robinette]

If you buy a pump from Harbor F remember that they are oil type units and you MUST have a "oil from air filter" system which are expensive. If not your whole shop and everything in it will be covered with oil.
I was going to get one then waited and got a $100.00 Gast{spelling} pump that works just great. A friend got a HF oil type and is trying to build a filter system and degrease his whole shop.
Just some info.

[Jon Nuckles]

I have used the veneer supplies (Joe Woodworker) venturi system for a large veneer bag and the compressor didn't kick on very often once the bag was drawn down. The system has the check valve that Thom mentioned, which shuts off the venturi line when sufficient vacuum is achieved. I believe the other secret is that it includes a separate reservoir that holds "vacuumed" air so small leaks don't cause quick pressure drops. Joe Woodworker's site, linked by Steve, has a lot of information on the capacity of the various setups and the compressor requirements to use them. I never used it for vacuum chucking, but the compressor only ran for about a minute of every fifteen or so for veneer pressing. The compressor had a 60 gallon tank and the vacuum reservoir was probably 5 gallons (which is bigger than the one Joe's site recommends building, I believe). I'm not recommending it because I don't really know how it would work for vacuum chucking, but Joe takes phone calls and is very knowledgeable and helpful.

[Shawn Pachlhofer]

If you buy a pump from Harbor F remember that they are oil type units and you MUST have a "oil from air filter" system which are expensive. If not your whole shop and everything in it will be covered with oil.
I was going to get one then waited and got a $100.00 Gast{spelling} pump that works just great. A friend got a HF oil type and is trying to build a filter system and degrease his whole shop.
Just some info.

or, you can just cover the exhaust port with an old sock.

[Bob Bergstrom]

Google the " Furgal Vacuum Pump. Also advertised in the back of the AAW magazine. It's a whole system with all the parts. The pump is a oxygen generator pump used in hospitals. We have one at our club workshop and 3 members who have purchased them. They work very well for about the price you are looking at.

[cody michael]

If you buy a pump from Harbor F remember that they are oil type units and you MUST have a "oil from air filter" system which are expensive. If not your whole shop and everything in it will be covered with oil.
I was going to get one then waited and got a $100.00 Gast{spelling} pump that works just great. A friend got a HF oil type and is trying to build a filter system and degrease his whole shop.
Just some info.

sounds like a fix for rusting table tops!