Vacuum system

[Christ Kacoyannakis]

Hi all. Looking to put together a vacuum system (not a venturi powered off my compressor) for clamping, bending, holding and anything else I can think of. Not sure how much vacuum power (CFM) I need. Also I have found two companies that make pumps, Viot and Quality Vakuum Products. Are there any others I should look at? Also, the bags most of these companies sell seem pretty large. Do people buy large bags and somehow make them smaller (clamping off ends) or something? Totally new to this, but I can see the possibilities, and I have already seen how some clamping procedures I do might be better done with vacuum (and some that would not). Thanks!

[Bob Gramann]

I bought a Dayton diaphragm vacuum pump off of ebay for $65 a few years ago. It works my bridge clamp and my body holding clamp just fine. It’s rated for continuous use so it doesn’t even need a reservoir. You can see it if you ever come visit.

[Bill Raymond]

I bought a diaphragm vacuum pump from American Science and Surplus a number of years ago (they don't have them anymore) and made my own bag from heavy duty plastic sheet that can be bought at WalMart or a fabric store, glued the seams with vinyl cement and used a piece of threaded steel tubing (out of an old lamp) some washers, nuts and rubber gasket material to connect to the vacuum tubing. Laminated an arched guitar back with it with no problem.

[Bob Hammond]

also look for Gast pumps - many of these pumps are both vacuum and compression, with both single and double diaphragms. also, you might look for medical aspirator pumps - they come mounted and often with noise suppressors and bottles, and so they can be handy for other jobs

[Bob Francis]

also look for Gast pumps - many of these pumps are both vacuum and compression, with both single and double diaphragms. also, you might look for medical aspirator pumps - they come mounted and often with noise suppressors and bottles, and so they can be handy for other jobs

Gast pumps are very reliable and often available at surplus sites. It almost seems that they are decertified for med use but nothing wrong with them.

[Randy Roberts]

Christ,
Another route you might want to consider is using the compressor out of an old refrigerator or freezer.

Here's some discussions from years back on vacuum systems:

http://www.mimf.com/library/Hot_hide_gl ... -2009.html

http://www.mimf.com/library/Super-simpl ... -2012.html

http://www.mimf.com/library/Vacuum_brid ... -2011.html

[Christ Kacoyannakis]

Thanks all.

A few things I forgot to ask. Is the plastic bag itself enough to glue parts together? So, if I applied glue to two parts and pin them together with 1/8 wood dowels so they don't move, and put them in the bag, is that going to be strong enough to apply gluing pressure (this is not something I am veneering, but more like a three piece neck).

Also, can you buy different size bags? All the ones I see online are huge.

Finally, does glue stick to the plastic? I think I saw something where they put polyester material over the part, because epoxy does not stick to polyester (is that correct?), but I am also wondering about hide glue and regular PVA glue.

Thanks.

[Barry Daniels]

A bag is not enough pressure for a laminated neck. They are really intended for thin veneered laminations. Different types of glue can stick to different types of bag materials. Bags are available in different sizes but they are mostly large because most people are doing veneered panels. If you want something smaller you can make your own bag fairly easily. Or just use a large bag with part of it rolled up unused. Hide glue and PVA glues can be used in a bag but are not ideal.

[Christ Kacoyannakis]

Thanks Barry. So, another application I was thinking of using the vacuum for was laminating a 5/8 inch piece of hardwood onto a piece of 1.5 inch mahogany to make a carved top electric guitar body.

I thought this would be a good use for the vacuum bag. Do you think that would work with a plastic bag? The two parts are flat and I just need even pressure over the entire top surface. Right now, I have a complicated set of wood clamps with bolts that have to be tightened, and it takes quite a while to tighten them all and I am never sure if I get even pressure over the whole area.

[Bob Francis]

I'm not Barry but I do dome vacuum bagging and in a word the answer is yes.

[Bob Gramann]

Hide glue does not form a permanent bond with the rubber clamp material that I am using. I clean it with hot water after the glue is dry. For a drop top, I would consider making a frame clamp a bit larger than the guitar body in the manner of the vaccum bridge clamp that LMI sells. The vacuum clamp would seal to the table that the guitar body is on and the rubber would pull down under vacuum and totally clamp the pieces. Personally, I would experiment with hot hide glue for this. Warming the pieces w ith a heat gun would give plenty of working time for the hot hide glue. I would worry about that large a Titebond joint moving with weather changes and producing a palpable edge.

[Pat Foster]

+1 for the Gast pumps.

I found a lot of good info and parts at veneersupplies

Pat

[Barry Daniels]

Thanks Barry. So, another application I was thinking of using the vacuum for was laminating a 5/8 inch piece of hardwood onto a piece of 1.5 inch mahogany to make a carved top electric guitar body.

I thought this would be a good use for the vacuum bag. Do you think that would work with a plastic bag? The two parts are flat and I just need even pressure over the entire top surface. Right now, I have a complicated set of wood clamps with bolts that have to be tightened, and it takes quite a while to tighten them all and I am never sure if I get even pressure over the whole area.

If the wood is much thicker than veneer then the joint has to fit well enough that not much pressure is required to completely close the entire joint. I am giving you the benefit of my years of experimentation with vacuum bagging that getting good glue joints are not a sure thing. Many places will often have compromised joints due to the the way things fit together, poor vacuum penetration, and other factors. Laminating a guitar body with 5/8" cap is possible, but a bit of a challenge. I tried laminated guitar sides several times and gave up it.

Personally I would never try hot hide glue or PVA in a vacuum bag. Epoxy or Urea Formaldehyde (UniBond 800) glues are better choices for vacuum veneering.

[Bob Hammond]

Just a couple of items.

1. Gast pumps can be rebuilt with kits that include the seals and reed valves. So if the motor runs and it doesn't look otherwise abused, then you can pick up a good quality pump cheap.

2. For laminating a neck, I think I'd place some small dowels in the interior laminations to index the layers, and then wrap with stretched strips cut from bicycle or auto innertubes.