Official Luthiers Forum!

Hello,

I've recently purchased a small CNC router and I'm in need of a good vacuum system to hold guitar bodies, necks and whatnot down for machining; also, I plan to start glueing bodies together with vacuum bags. Are there specific systems that would be ideal for these applications?

So far I've found these sources for pumps:
http://www.2linc.com/venturi_vacuum.htm
http://www.piab.com/
http://www.vaccon.com/Venturi-vacuum-pumps.aspx

I have a 80gallon air compressor rated at 17cfm @ 90psi. Let me know if further information is required.

Thanks,
David

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David
Vancouver, BC

I'd go for a pump/reservoir system over a venturi. It will cost more but it's no fun to run your air compressor for hours on end.

There's lots of good info at http://www.joewoodworker.com/veneering/welcome.htm

You can get pumps for cheap on ebay occasionally. Some folks have had good luck with refrigerator pumps to but they can be slow and inefficient.

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http://www.chassonguitars.com

Joe Woodworker has a design for using a vacuum switch with a venturi pump so that it doesn't run you compressor continuously. I built one like it and it works great.

I use a Gast rotary vane type vacuum pump with 3cfm, maybe 5cfm I don't remember, for both of those types of operation. No tank, no problems and I've used the pump for a long time. A vacuum generator running off a compressor would probably need a tank so the compressor doesn't run all the time.
Vacuum pumps run a lot quieter that compressors also.

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Jim Watts
http://jameswattsguitars.com

I use a Venturi, but I need max vacuum fast (lots of CFM) and it does eat up a lot of air. I have them from a couple different places, but Vaccon makes the nicest ones (and their prices are very good as well, I'd have only bought from them if I'd known about them when I started).

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I have a 4'x8' cnc router and I use 2 Fein shop vac's for all of my hold down (holds down a 4x8 sheet with holes in it with no problem. Im sure 1 could hold down your pieces easily. A simple grid with some gasket foam and you are rolling.

Im sure some people that are not familiar with the Fein's for hold down. But it is a proven system that has been used time and time again (check shopbot message board). I have ran mine for over 8 hours with no problems. They are cooled by a second fan and not by the air that passes through.

A shop vac system might hold down a large sheet reasonably well, but it absolutely will not hold down something the size of a guitar neck. It's a matter of vacuum*surface area and the shop vac is pulling a very low vacuum on what will be a very low surface area on something like a neck (or even less on a bridge!).

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services