Vacuum frame membrane material - created 10-06-2004

McCafferty, Terry - 10/06/2004.00:15:18

I recently toured the Martin guitar factory. During the tour, I noticed the vacuum frames they use for clamping braces to tops and backs while the glue dries. The fixture was a thick aluminum plate with an aluminum frame (like a picture frame) hinged to it. The frame was covered with a rubber membrane and had a gasket to seal the frame to the plate. The guitar back was laid on the plate, the braces positioned, the frame closed, and a vacuum applied.

The guide was not able to tell me what the membrane material was. I am familiar with the clear plastics that the vacuum clamping industry uses. This material was tan and appeared to be some sort of rubber.

Does anyone know what it is and where it can be purchased?

Chinchen, Jason - 10/06/2004.02:38:00
Lufier in training

The material is probably latex.. LMI or stewmac. Can I say that?

sysop - 10/06/2004.07:25:58
Deb Suran

Sure!

Chinchen, Jason - 10/06/2004.19:29:04
Lufier in training

yay.

Poling, Brock - 10/07/2004.08:11:46
Columbus, OH

You can buy what you are looking for at McMaster Carr (google for their web site).

Once you get in use their search engine to look for "rubber sheet" and the stuff you want is natural latex rubber sheet. They sell it in .05" thick sheets 42" wide and it is priced by the linear foot.

It is kind of expensive, but exactly what you are looking for.

Hope this helps.

Foster, Bert - 10/07/2004.08:34:45
Try to be the person your dog thinks you are.

Search for rubbermann7 on ebay as he sells small quantities.

Also search google for american rubber group they have a site with lots of info on sheet rubber, natural and synthetic.

Robinson, David - 10/07/2004.13:18:48
future flatlander

I thought the membrane alot use was a urethane rubber. Also available at McMaster Carr

Debelleix, Max - 10/08/2004.03:58:14
Feeling like Galileo!

Hi everybody!

I was thinking it was thicker that 1.5MM, more somethink like 5MM, you know like the plastic partitions in factories, the big strips of transparent pvc ruber hanging from the sealing or frame.

Best regards.

Max.

Robinson, David - 10/08/2004.10:38:45
future flatlander

I use, I think, 0.040" PVC on my vacuum frames. It is sold as boat window material at the boating store. It really conforms to shapes, and when it wears out it is cheap to replace.

McCafferty, Terry - 10/10/2004.06:41:01

Thanks a lot folks for the response on this. I couldn't find the source referenced on ebay. I will go ahead and order the .050" latex from McMaster Carr.

I guess I'll just build a frame out of maple. When you glue braces this way, do you put a "grooved plate" or something under the instrument top or back to allow airflow? I was curious if you would still get vacuum out in the "center" of everything.

Thanks again.

Poling, Brock - 10/10/2004.14:38:51
Columbus, OH

It would be worth a trip over to Don William's site (search on dewguitars). He has a nice rig outlined. His HTML is a little borked (for me), but do a view source in a web browser and it is easy to get the missing text.

sysop - 10/10/2004.15:20:09
Deb Suran

Sorry, Brock - no links at all, to any pages any website selling guitars, including images. Thanks.

Poling, Brock - 10/10/2004.17:05:17
Columbus, OH

Bummer... sorry Deb. I tried to give the info and be respectful of the rules -- no offense intended.

Anyway.. it is worth it to check out Michael Keller's site. He has a jig picture that is really nice. You will have to hunt for it, but it is worth it.

sysop - 10/10/2004.17:10:29
Deb Suran

No problem.

Daniels, Barry - 10/10/2004.21:26:59
MIMForum Staff

Many vacuum baggers use a "bleeder" to help evacuate the air. The bleeder is a layer of non-woven polyester fabric that is laid over the top directly under the vacuum membrane, and it keeps air flow open across the layup. The bleeder material sold by many vacuum bag suppliers is very similar to what you can find at the local fabric supplier. Look for non-woven polyester thats about 1/8" thick.