Laminate doublebass

[Nicolas Martinez]

Hi so i was wondering if anyone can help me out i'm building a laminate double bass i was wondering if anyone knows how to make a mold in order to get the arch in the top and back.

[Thomas Erickson]

Sculpt it in clay/wood/whatever you like and then lay up fiberglass over that. This will be your top; when it is cured, remove it and lay 'glass into the underside to make the bottom plate. Mount both of your 'glass plates in concrete slabs and there's your form.

It isn't that simple, really, but that's the idea of one way to do it - I haven't made a bass from laminate materials, but I used to press skateboard decks like this.

[Nicolas Martinez]

Sculpt it in clay/wood/whatever you like and then lay up fiberglass over that. This will be your top; when it is cured, remove it and lay 'glass into the underside to make the bottom plate. Mount both of your 'glass plates in concrete slabs and there's your form.

It isn't that simple, really, but that's the idea of one way to do it - I haven't made a bass from laminate materials, but I used to press skateboard decks like this.

do you know where i could get sonme decent wood for a laminate bass

[Thomas Erickson]

I don't.

I am curious though - why do you want to make a laminated bass? :confused:

[Adrian Levi]

I don't.

I am curious though - why do you want to make a laminated bass? :confused:

+1

ply basses are probably super hard to make without super specialized machinery . Im thinking you'd need positive and negative type press moulds etc ?

[james condino]

An inside and outside mold / press system is an outdated approach to a laminate concept, unless you've got a huge industrial infrastructure. A much more simple method would be to make one mold that reflects the desired arches you are looking for. It could be either inside or outside, just a matter of your preference and approach. I'd probably just carve or grind one out of mdf. You could also make a nice one by plaster casting an existing plate, but the plaster can be a bit fragile. I've also seen it done by simply making a series of stacked forms similar to a topographic map out of very thin materials; the choice is yours.

Stack your glued up laminates on top of the single form, put it all inside a large sealed bag, and use a vacuum pump to draw out all of the excess air and then draw down the pressure from the entire system. You should be able to get approx. 20 lbs /square inch or more with very even distribution across the entire plate. You'll need to use a glue with a longer open working time in order to get everything put together and in place before it all sets up.

I'll admit that I've never used a system like this to build a laminated bass top (I prefer to carve them from solid spruce for a number of reasons). I have used the same concept for veneering a 30' long conference table top, to make countless jigs and small parts in a production environment, and to glue up the bracing on a LOT of steel string acoustic guitars, so I'm very familiar with it. You could use the exact same setup to also layer up a nice carbon fiber plate. I'd guess that Ken has some sort of vacuum wizardry in his production shop for some part of the process...

The crux of the task is getting your arched molding plate- either carve, cast, or stack it. After that, you can fabricate a very nice bass sized bag for under $50. A commercial vacuum pump will run about $500, but you can build one yourself out of salvaged parts for $200 or less. I believe that you can also buy an in line gadget that will work in conjunction with your standard shop compressor to reverse the flow and create a vacuum; I've never used one. These type of systems are fairly popular in the guitar building circles; you should be able to find lots of information on the web about them. They are not difficult to make, nor are they expensive.

You have to go to almost the same amount of total work to gear up to make one or 100. Thomas summed up the real question- why do you want to make a plywood bass? As a novice, you'll likely spend 50 hours ( best case scenario!) to get one top made. I can carve a beautiful solid spruce top to completion in less time than that, with much more pleasing end results, and the process is near zen like bliss for the top plate ( backs are a different story!). Of all the things I do as a working luthier, carving spruce by hand is my favorite.

j.

[Thomas Erickson]

^^^ nice post!

Vacuum bag is a good idea; I haven't used it though.

I did try the "stacked" method of making a form, and had problems with surface cracking/impressions. I tend to think fiberglass over a clay plug is the best solution because the materials are relatively cheap and easy to source, easy to work with and they don't take any special tools or skills.

Ultimately though I think the "why" overrides any of it - nobody wants a plywood bass, and even if a laminated back was desired for whatever reason it might as well be flat! ;)