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Has anyone ever built a vacuum table? One for holding thin pieces of wood in places while working them with sanders/routers? Thinking 2x4 feet... shop vac driven....?

Mike

Had good down draft built by Bill at his shop and worked well. I am selling a jointer and shaper so can get one from Griz. Tried the table top type that shop fox and delta had. Not work well at all. If make one need blower and vacuum in the unit. I am just going to buy one, but shouldn't be to hard to build.

If you're talking vacuum hold-down then you're going to need a whole lot more than a shop-vac to handle 2x4 feet, unless it's a 40HP shop vac. You can get by with a small vacuum pump for hold-down if you seal properly around your parts.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

A good article to read might be "The Universal Vacuum Island" by Charels Fox. You can find it in the Winter 2006 American Lutherie from GAL. Fox uses dicarded refrigerator pumps for the vacuum. No plans or anything but well described and plenty of pix and good ideas with feedback.

Tim

To maintain a good hold about 25 ft of vac is required and the vac must be isolated or sealed in relation to the part it is holding by some sort of gasket seal equal to or smaller than the dimensions of the piece being held so that the vac pressure constant. It is pretty easy to build clamping system that uses a venture vac generator of a vac pump, varying sized O-ring type gaskets to form the seal and different channels for the different sized O-rings to hold various sized materials . But to have one table, one seal to fit varying sized objects is not going to work. And certainly not being wet/dry vac powered.

Be Aware that if the parts to be held have contour. Like a domed back or top the gasket must be tall enough that with the vac pulled the contour does not contact any part of the fixture or the seal is to easily broken.

Mike one thing I could suggest is the possibility of using V-clamp system

http://www.vac-clamp.com/

You can run this in parallel series. Each one has its own venture valve built in and they operate off of your compressed air system via an on off valve. They do a good job I have 4 that I use through out the shop and some times together. Easy to configure in groups or as singles.

WOW! That is awesome looking product... Do you use it to hold down the guitar body? Does it take two to get a secure hold on a guitar?

No it just takes 1. Because of the dish you will need to use the tall seals (see the web site) or Woodcraft.com The tall seal is ordered seprate. Also be sure you compressor can produce enough constant cmf at 60psi check the web site for info.

I would not use it to hold a top or back during brace shaving as it will over hang and it would be possible to crack the top or back but I use mine to hold assembled bodies for all sorts of tasks.

I have one mounted to a T shaped board I use in my vice when I need to pivot, one perminatly mounted to a work bench and a couple that I move around from place to place. I bought just one on/off valve as it is easy to move the hose from one to another.

The only thing I dislike about these is that because the seal is an open length of oval rubber you must be sure you have a tight butt-up of seal to seal. If there is a leak in the seal the of course the vacuum is broken. I solved this by making up seal specific to the job that the ends are closed. but this is not much of an issue to use the open ended seal if you reform the seal each use and intermittently if used for extended periods. The seal does not seem to move once vacuum is drawn but when you release the part the seal ends want to move away from each other a tad. so you have to be sure and close it back before next use if you leave the ends open so that you can adjust to a specific size.

Since I have pretty much specific uses I just cut the seal material to length and use ABS adhesive and glued the ends together. The rubber seals do shrink with age but not a problem as it will stretch. I have had mine for just over a year or so and I use the heck out of them.

That is good and useful info Michael, thanks!

This forum has just popped up on our website statistics panel, so I thought it prudent to assist if required.

Mike you might be relieved to know that the seal now comes as a joined unit to avoid the very problem that you mention.
If you are concerned about having too much clamping power, particularly on thinner materials, try turning the air supply pressure down a bit. At 60 psi supply, vacuum is still quite high, but about 50 it tapers off noticeably.
As far as maintenance goes, just use an air dusting gun in the vacuum port and exhaust port occasionally and all should be good.
If you want the clamp to last pretty much forever (not the seal/gasket) keep your compressed air supply clean. Condensate is not a problem.

Errol at V-Clamp