Official Luthiers Forum!

Well, I picked up a Gast vacuum pump on ebay that is suppose to pull 25in hg.I have very limited experience with air compressor much less vacuums. All i know is that I have to get the vacuum from the pump to the press fixture. I have seen setups with filters, bleed valves, gauges etc. Can someone point me in the direction how to set up this thing. Also does the vacuum pressure need to adjusted down from 25 in hg or is that sufficient?

As always thanks
Richard

Try looking at this site. It will give you some ideas on the process.

http://joewoodworker.com/

Mike

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I'm outside looking in, just farther from the window than most.

I built the Joe woodworker pump and it works great. I too used a gast pump.
Adding the reservoirs really makes it quiet.

I made the EVS system
http://www.veneersupplies.com/vacuum_press.php

Andy

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Andy Z.
http://www.lazydogguitars.com

What are you using it for?

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http://www.chassonguitars.com

Braces and bridge clamping mostly

r

Richard, here's a simple set up that works well for braces.



you need a small membrane for bridges like lmi sells.

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Jim Watts
http://jameswattsguitars.com

Richard,
I bouight the V2 kit from Joewoodworker, and built my own vacuum generator. You still need a compressor for this one. I built mine a little different than the plan callls for. I used four 4" pvc's, 24" long and modified the manifold to accomodate the extra pipes. This gave me more volume to keep the unit from turning on all the time. It works great. I bought the bag material from Joe also. Joe sells everything you need. I use mine to glue up the braces. I also put a contour dish in the bag to match whatever contour I am gluing up. I do 12' on backs, and 25 on tops. The vacuum clamping process makes a huge difference in the sound, as far as I am concerned. And it is a lot easier than go-bars or clamps.
Good luck.
Mike R.

You shouldn't need to go lower than 25 in/hg for gluing. I know some folks worry about braces imprinting in the top but when I was using vacuum, I always used as much pressure as I could get and never had problems.

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http://www.chassonguitars.com

Just remember that the max pressure you can get is 15psi. at sea level. Unless you put it into a pressure chamber.

Chris so you are saying no matter how strong the vac system is even though the front end of the vac may pull 25in hg that you will never get more than 15in hg at the jig?
BTW thanks for the top thickness video, that was interesting, I am trying it on my most recent build

Thanks

Richard

you are confusing in.hg with psi. they are differing measures. normal atmospheric pressure is ca. 30 in hg and ca 14.7 psi. at sea level. thus a vac of 25 in hg will only deliver about 11.6 psi of clamping pressure.

don't worry, the pump will do the job.

i second the recommendation to check out joe woodworkers site.

I made a simple vacuum press... I made a wood frame the same dimensions as my radius dishes, got some heavy duty clear plastic from Joanne's fabric shop, and some weather stripping from Home Depot. You can find used gast pumps on e-bay. I used z-poxy on my radius dishes so the edges are smooth and can make a seal. I use a radius dish on the bottom, followed by some wax paper, followed by the top or back, ... glue-up the braces (on the top you do a few at a time; x-braces first, so on) and cover with the frame with the plastic glued on... and the weather stripping on the edges. I got a connector from a friend (who got it from joe woodworker), that goes thru the plastic and attaches to the tube that leads to the gast pump. I clamp the corners and the sides.

I'm sure the resevoirs are nice, but I just keep running the pump. The vacuum seems to be adequate because when I have the pump going, I can't squeeze out anymore glue with my hand and the top or back is pushed solidly into the radius dish. The clear plastic is nice because you can see what's going on. This system is great! ...better than gobars...

One more thing, if you decide you need resevoirs, buy an air tank from Harbor freight. They are cheaper than building multiple tanks from PVC. The end caps for PVC run about 6 to 7 $ each for 3" or 4" I bought a tank for around 20+ $ on sale. Only have to worry about one fitting leaking as well.

Just my .02cents


MK

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I'm outside looking in, just farther from the window than most.

For the membrane, I found that a plain, clear, vinyl shower curtain from the dollar store works well.

Rene