Cupping and laminating 1/8" wood plys into a specific shape.

[Dolmetscher007]

I need to make a laminated "arched" guitar top. Here is a picture of what I am talking about.

All guitar makers do it slightly differently. For the most part, it is just 3-4 sheets of 1/8" plys that they glue up, place over a mold, and use some pressure or heat activated glue and press the plys over the mold. The DIY version is to use a vacuum press bag. The problem with that, so I've heard, is that it only comes out good less than 50% of the time. The pressure or heat press systems that the pros use always work, but the press machines are terribly expensive. The vacuum bags are much less expensive, but you will blow through big bucks in ruined wood; keep in mind, guitar wood is usually expensive and beautiful. Not to mention, the days wasted waiting for glues to dry.

Anyone got an outside the box idea?

[Llama]

9 minutes ago, Dolmetscher007 said:

guitar wood

I have always had a problem with this. The idea that guitars are made out of some spectacular wood that only luthiers can get ahold of. It's just wood... The same wood Gibson uses for necks furniture makers use for legs. It's just wood. Fender didn't use "luthier grade" poplar or ash. Hell, PRS used to take apart old pieces of furniture to build his tops out of. Some of his best work. It's all tree wood. Sorry, rant over.

To the opportunity... You can simply carve the top. Unless you are doing a bunch of these, just set up (or purchase) profile templates and carve away the stuff that doesn't belong.

[Dolmetscher007]

Thanks Llama... I agree with you completely about the whole "exotic wood" argument. I don't think that fancy AAAA figured wood makes a better guitar. In fact, I would argue that, due to inconsistencies and internal weaknesses, highly figured wood makes a worse guitar. My plan was to use just standard furniture-grade woods for the back, sides, and all the top plys, except for the outer-most top ply, to make the thing purdy! ;-)

I definitely do not want to make a carved top. I want to learn to laminate for sure. 

[drzaius]

You could use lots of clamps & cauls that would give you a MUCH higher PSI than vacuum would. That doesn't help with the heat though.

[mds2]

I would carve that, myself. 

[Dolmetscher007]

I think I have a cool idea. It's a total hail mary, but it may just work. There is a company called Roarockit that makes a product called the, "Thin Air Press System." It is literally nothing more than a plastic bag with one of those wine-saver rubber cork-valves in the center. You glue up your veneers, place them on the mold you want them to mold to, stick the whole thing in the bag, seal the bag with this double sided tape stuff, and suck the air out, literally with one of those pump-action wine saver things that you can buy at the grocery store.

I am going to go to Wal*Mart, buy a clear plastic shower curtain liner for $9, come home and use aluminum foil and an iron to crimp and melt the thing into a "bag." I'll then work on figuring out a way to get one of those little rubber nipple valve-corks to fit into the top of the bag air tight. Then I am going to make a mold of something, glue up some scrap veneers, and see if I can suck the air out hard enough to mold the veneers into the shape. If it works, that will be amazing. 

Anyone care to get a bet pool going?

[drzaius]

1 hour ago, Dolmetscher007 said:

I think I have a cool idea. It's a total hail mary, but it may just work. There is a company called Roarockit that makes a product called the, "Thin Air Press System."

That's just a cheap vacuum press. With any vacuum system, the most clamping pressure you can get is atmospheric, which is about 15 psi.

Trying to force veneers into a 3D shape while gluing them up, it seems to me would take quite a bit of pressure.

No experience here, just thinking out loud.

[wtnhighlander]

The big advantage of a vacuum press is that the 15 psi is evenly applied to every point on the surface. Clamps won't do that. However, if you can make the proper 2-piece mold, one of those hydraulic jack powered bearing presses can prouduce 20 tons of force. http://m.harborfreight.com/20-ton-shop-press-32879.html

[drzaius]

Good parallel clamps will do 1500 lbs each. Say the piece is 12" x 24". That's 288 sq" x 15 lbs/sq" = 4320 lbs with a vacuum press. If you use 10 clamps on each side, that's 20 clamps x 1500 lbs = 30,000 lbs. Not quite 20 tons, but then you don't need a hydraulic press.

I guess it just depends on what you have on hand.

If you made the mold out of 2" thick MDF & then preheated the molds in the oven, I wonder if the added heat would help out. Might be fun to experiment with that.