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I scored a vacuum pump, medical surplus. What have been the experiences of the forumites with vacuum bridge clamping? Technique? Times? Pitfalls?
Thanks
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I use hide glue so I have to rehearse and get every thing just right. It's a little stressful but I can see where it will get better with more experience.
Another thing is my vacuum frame leaks no matter what I've tried but as long as the pump is running it's more than able to keep up and I'm glad I went the vac route rather than traditional clamps.


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I haven't used my clamp yet, but it seems to hold the vacuum perfectly! I used a cheap chopping block that I snuck from the kitchen. I used #10 machine screws to hold the clamp assembly together with vinyl sandwiched between! Veneersupply.com is a great resource for everything you need for vacuuming!!

Good idea for using the cutting board material. What did you use for the bottom seal material and did you have to leave some slack in the vinyl? I suppose vinyl would not stretch like the rubber often used in these jigs. Thanks-Bob

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“ The meaning of life is to find your gift and the purpose of life is to give it away” Pablo Picasso

No slack , the vinyl stretches 3 times its length and width! I used a very soft closed cell foam from McMaster Carr! Also made a body clamp to hold while binding.

Terry I have used vacuum for about 7 years now and won't go back. But that is for phases of bracing and not just the bridge. Only problem for me at first was holding the bridge in place. But now just use a couple of bridge pins I made up of stuff glue doesn't adhere to and keeps everything tight.

I use closed foam I got from Joe the Woodworker (anyway think that is the guy as got a big roll when built my frames and who I got compressor from) Since top is probably on a radius I just pa little pressure for making a good seal is all that is needed (if that is your problem talking about)

By way my son just finished med school (at 36) He was going to go ortho surgery, but with long residency, and he decided he loves EM decided to go that way. Still a 4 year residency though.

Thanks Stan!
I've had an old medical vacuum pump in my basement for years but never got around to going with vacuum clamping. I got a massively overbuilt classical in with a lifted bridge. Braces so big and soundhole so small no clamp I know of will fit. Figured it was time to take the leap to vacuum.

How long do you wait before addressing squeeze out? Total clamping time?

Hey congrats on your son's achievements! ER medicine is a great gig. Ortho is a long hard slug and then a ton of night and weekend work if you do trauma. I was 35 before I actually started practice, he'd probably be 42 or 43. I think he made a good call.

Great to see you posting here.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Terence,
I use fish glue so repairs are easier, but I have a long working time which I appreciate so I'm not rushed.
I hold vacuum on it for an hour and a half, then take it off and clean the squeeze out with a damp rag; then back under vacuum for another hour and a half. I've done it this way on both classicals I've built and found it really user friendly,
Mike

I always wanted to try vacume clamping but seems like the pumps are pricey.
Does anyone use the valve you can hook to a compressor?

FREE VACUUM PUMPS !!! Now that I've got your attention, I've been using old refrigeration pumps for years. I have always scrounged them from heat/ air conditioning contractors. They work great, and have never cost more than a handshake and a smile.

Al

got to practice my smiling skills, then.

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member of the guild of professional dilettantes

Steve Smith has a plan for a bridge clamp in the tutorial section.
http://www.luthiersforum.com/forum/viewtopic.php?f=10117&t=23895

I bought the LMI foam gasket and used that and Steve's plan to build this one.





I used a rubber exercise stretch band for the rubber membrane.

My big lesson learned is that the membrane needs to be really clean when you glue the bridge on. I had done a test run on something and neglected to clean two bits of dried glue off the membrane. I found and impression in my finish in the spot where I first had the clamp on. Then when I removed it to clean the glue squeeze out up, I didn't look at the membrane again and left two more spots in the top.

Other than that, vacuum clamping the bridge was a breeze. I didn't even realize I had done that till I was working out my final polishing.

David,

What are you using for the base of your body clamp? That looks slick.

John

Terry on the braces I get it up to pressure for if remember right about 10 minutes or so and then use a chisel to take off the squeeze out. And then turn the pressure on another 10-15 minutes. Kind of a thing you have to work out with your rig. At a shop I worked at we had an air compressor and mine is the (can't think of the right term) electric rig. I just start checking about 8 minutes into it and when the glue is like a rubber I take it off with chisel as it is pretty clean that way.

For Bridge I keep in on an hour or more. Don't know why, just do.

I have a radius disk I put the top and back on and then for the back and X braces a little wood clamp made up to hold them in place. I made sure used good cauls to make sure get a good distribution of glues. On vacuum need enough to get good adhesion, but not overdo the glue and nice even amount on the whole brace.

I love vacuum and wish a way to glue the plates to the rims, but that would be one big clamp rig and not sure a thing want to try and hassle with.

The first try went well. I made little cauls to help even the pressure on the classical bridge. Got 22" of vacuum.
Cleaned squeeze out at 15" which seemed just right. Left clamped another hour. So far so good. Thanks all for the help.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Anyone glue the bracing with a vacuum clam?

I remember seeing someone post photos doing that with a clamshell type fixture but it's probably been over 5 years and I think it was on the MIMF.

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Steve Smith
"Music is what feelings sound like"

Like this?

http://kennethmichaelguitars.com/vacuumclamp.html

Similar except the one I recall was hinge mounted on a purpose-built table. It may have been for low volume production.

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Steve Smith
"Music is what feelings sound like"

I'm using vacuum clamping for braces. The set up I built in the photo below is based on the design detailed here: http://www.joewoodworker.com/veneering/vacuum-frame-press.htm

My set up is simpler than most because it only has a top which is easy to store out of the way when not in use. No bottom like the clam shell type presses. The top of my free standing workbench comes from a biology lab and has a flat, hard, smooth surface and it serves as the bottom. The vacuum frame seals nicely on that surface. I place the appropriate sanding dish on the bench, cover the sand paper with paper, place the top or back on that, places braces, and then put the vacuum frame over that and pull a vacuum. I use cam clamps on the edges of the frame to to clamp it to the bench top to get the vacuum started quickly. Once the vacuum is established, they aren't necessary. Works like a charm. There is no skating of the braces at all as the vacuum is drawn down.

I'm using a small GAST vacuum pump I got on ebay for 90 bucks.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

I love using my repurposed fridge pump for vacuum clamping. Works perfect for my needs, currently I'm using It for bridges and guitar holding.

For bridges I clamp for about 10 mins, unclamp, clean squeeze out, reclamp for an hour. Then let cure overnight before I string up.

Worked great for me. I got some odd doliscoloration in nitro one time but now use a thin layer of plastic wrap as barrier, no issues since.

Joel

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http://Michaudmade.com

Here's a bridge glue up

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http://Michaudmade.com

I went low tech on my bridge gluing. Some masking tape, Saran Wrap, piece of tubing, couple vacuum cleaner motors. Not a heck of a lot of vacuum but worked anyway.

Here's my "vacuum clam", btw that's a great name for this tool. I have always wondered what to call it, "frame" doesn't do it justice and bag is not accurate.

Joel,

I 'found a mini fridge that has a working compressor in it. I was wondering if you could point me to a tutorial or give some tips on how to set it up and what supplies I need to get it going?

Thanks

Wes