Darryl Keil Last Activity 2025-09-09 11:09 AM
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David Shores

Posts: 1

Joined: 2006-08-22
Location: Dublin, Georgia

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Subject : Vacupressing Guitar tops/backs
Posted : 2006-08-22 7:45 PM
Post #33348
I'm making my first acoustic guitar. And I just bought a used Industrial Vacupress with a big bag (like, maybe 49 x 97?). The guitar top and back will need to be clamped into a "dish" with a radius of 28 and 16 feet, respectively. Has anyone got any experience with gluing up guitar parts with a vacuum bag? The top and back would have "bracing" pieces glued into precise positions. The other question is, do I need a smaller bag to do this? Could I just fold the bag and use the portion closest to one end?

I've never done any vacuum veneering, so my questions are probably quite basic.

thanks,

david


 
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Darryl Keil

Posts: 1455

Joined: 2003-05-22
Location: Maine

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Subject : RE: Vacupressing Guitar tops/backs
Posted : 2006-08-23 7:51 AM
Post #33350 - In reply to #33348
David,

I'm not experienced in gluing up the guitar party you talk about but I do have customers that do it, so it can be done.

As far as the bag goes you can easily use only a part of the bag. Just make a small platen, the board with the shallow grooves in it, roll up the extra bag behind your platen.

Sincerely
Darryl Keil


 
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Bob Peticolas

Posts: 2

Joined: 2006-08-24
Location: North Providence, RI

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Subject : RE: Vacupressing Guitar tops/backs
Posted : 2006-08-24 9:34 AM
Post #33357 - In reply to #33348
I know guitar makers do use vacuum for bracing the top and back, but I don't think they use a standard bag. The radius goes the wrong way. Since the radiused dish is taller at the edges and shorter in the middle, the vacuum bag will not provide good clamping pressure in the middle area.

I believe they use a sort of rubber gasket but I don't know the details.


 
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Don Stephan

Posts: 825

Joined: 2003-07-18
Location: Cincinnati, Ohio

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Subject : RE: Vacupressing Guitar tops/backs
Posted : 2006-08-27 11:54 AM
Post #33364 - In reply to #33357
If the radius "goes the wrong way" there are at least a couple solutions.

One would be to fabricate a matching top caul out of tight styrofoam using coarse sandpaper, files and rasps, etc to shape the curved side. Since the top surface of the foam would be flat the clamping pressure on the veneeer would be good.

A second solution was suggested by Craig's response to another thread. If a piece of laminate is used for the top caul, it should offer little friction to the underside of the vacuum bag. Increase the vacuum gradually, stopping the pump as needed to shape the laminate and vacuum bag to the convex (?) curve of the veneer. I think there is a segment on Darryl's second video on vacuum pressing a convex curve in cove molding that might be helpful.


 
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Bob Peticolas

Posts: 2

Joined: 2006-08-24
Location: North Providence, RI

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Subject : RE: Vacupressing Guitar tops/backs
Posted : 2006-09-13 8:20 PM
Post #33384 - In reply to #33364
I like Don's ideas. You might also ask on www.mimf.com (musical instruments makers forum).
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