How are ply basses made?

fdeck · #1 06-06-2010, 04:00 PM

Strictly for my curiosity's sake. I am compelled to learn about how things work. How are the top and bottom plates of ply basses made?

JoshD · #2 06-06-2010, 05:07 PM

This was on How it's Made, but I can't find a link for you to watch.

This is about all I see otherwise.
http://www.youtube.com/watch?v=xFI0roDPNp0
setup by a local shop here in SD:
http://www.youtube.com/watch?v=cD4a54X93Xw

ctregan · #3 06-06-2010, 07:34 PM

Take a tour of the Englehart factory!
http://www.fretwellbass.com/showpage.php?cID=338

It does not show the tops being made. They may be outsourced (?)

You need a mold or form, in conjunction with some kind of press. The tricky part is getting the veneers pliable, in order to make the compound curves of the top.

Sonicfrog · #4 06-06-2010, 07:53 PM

Lots of glue and a skill saw!!! :-)

Dubbin · #5 06-06-2010, 09:24 PM

Hi Fdeck:

I'm curious if you get a response from sombody that knows. My father is a wooden boatbuilder and he always told me that plywood only bends in one direction which is definately the case if you ever tried working with a sheet on a curved surface. I can't see how they could possibly press one out of sheet stock but who knows? I suspect that the veneers are pressed and glued together all at once. There must be somebody on here that knows for sure.

fdeck · #6 06-06-2010, 09:42 PM

Quote:

Originally Posted by Dubbin

Hi Fdeck:

I'm curious if you get a response from sombody that knows. My father is a wooden boatbuilder and he always told me that plywood only bends in one direction which is definately the case if you ever tried working with a sheet on a curved surface. I can't see how they could possibly press one out of sheet stock but who knows? I suspect that the veneers are pressed and glued together all at once. There must be somebody on here that knows for sure.

I agree that the veneers have to be glued and pressed in one operation. This would also help the parts hold their shape over time.

In a former life, I designed the controls for huge steam heated molding presses that were used for molding surface relief into flat sheet plastic materials. While working on the biggest press, I wondered to myself if I could make plywood basses on such a machine.

Jake deVilliers · #7 06-06-2010, 10:57 PM

Quote:

Originally Posted by fdeck

I agree that the veneers have to be glued and pressed in one operation. This would also help the parts hold their shape over time.

In a former life, I designed the controls for huge steam heated molding presses that were used for molding surface relief into flat sheet plastic materials. While working on the biggest press, I wondered to myself if I could make plywood basses on such a machine.

Hey Francis, that's how the moulded backs were done on Guild guitars and I suspect on some basses too.

The Kays however, were laid up in a press and clamped until dry, first with hide glue and then with white glue toward the end. I've seen pix of the aluminium forms, one outer and one inner, that were used to create the tops and backs. Its too bad that Jerry and may Jane don't show the veneer presses on their site.

powerbass · #8 06-07-2010, 04:59 AM

I have done a lot of veneering with mechanical and vaccum presses. Typical veneer is 1/32" - 1/27" thick. Veneer can be made even more pliable with heat and an application of a flattening solution - this is typically water and glycerol sprayed on the veneer then flattened in a press between sheets of news paper. I imagine they used rotary cut veneer full width and there is only 3-4 plys. The hardest part of this process is making the 2 part form, if it is aluminum that is a big investment. What's nice about vaccum forming is you can use only 1 form. I hope to making a plywood top in the near future

ctregan · #9 06-07-2010, 06:52 AM

Quote:

Originally Posted by powerbass

Veneer can be made even more pliable with heat and an application of a flattening solution - this is typically water and glycerol sprayed on the veneer then flattened in a press between sheets of news paper.

The glycerol helps the wood retain water, and the effect is, a soft, pliable veneer that can be shaped (or flattened) much easier.

I am not sure if the water retention properties of glycerol would be good for musical instruments, unless it dissipates or could be washed out somehow.

Jack Clark · #10 06-07-2010, 11:32 AM

Woody Allen says they're made by two luthiers who each spread glue on one side of a layer of top wood, then they run at each other and . . . . Or was that chefs and fortune cookies? Yeah, I think that was it. . . . Nevermind. . . . A little more coffee, please? Thanks.

powerbass · #11 06-07-2010, 11:54 AM

The glycerol solution is very diluted. This process can take a day or 2, changing the newspaper frequently allows you to dial in the amount of water in the veneer. Burl and crotch veneer is notoriously crinkled and brittle so flattening the veneer is essential. After the process is done the veneer is very soft, flat and pliable

Paul Warburton · #12 06-07-2010, 01:49 PM

Quote:

Originally Posted by powerbass

crotch veneer is notoriously crinkled and brittle

I'm really sorry. I just couldn't help myself.

powerbass · #13 06-07-2010, 02:35 PM

I set myself up for that one!

Jake deVilliers · #14 06-07-2010, 05:00 PM

Quote:

Originally Posted by Paul Warburton

I'm really sorry. I just couldn't help myself.

And that's coming from an expert in the field!

fdeck · #15 06-07-2010, 07:13 PM

Quote:

Originally Posted by powerbass

I have done a lot of veneering with mechanical and vaccum presses. Typical veneer is 1/32" - 1/27" thick. Veneer can be made even more pliable with heat and an application of a flattening solution - this is typically water and glycerol sprayed on the veneer then flattened in a press between sheets of news paper. I imagine they used rotary cut veneer full width and there is only 3-4 plys. The hardest part of this process is making the 2 part form, if it is aluminum that is a big investment. What's nice about vaccum forming is you can use only 1 form. I hope to making a plywood top in the near future

With vacuum forming, it seems conceivable that the form could be carved from wood, but perhaps supported by a metal plate. I wonder if the pump needs to have enough capacity to maintain the flow of water vapor that would be pulled off the workpiece as it sets.

Or you could just form a new top using an old bass as a mold.

powerbass · #16 06-08-2010, 08:08 AM

Since the bass top is curved in 2 directions you would need to carve/shape a form just like a luthier carves a top. The form could be made from wood or I am interested in using foam like the foam used for house foundation insulation - it is easy to shape, is stable and strong. Metal reinforcement is not necessary, you need a flat, stable surface for the form to rest on. The moisture in the veneer is really not an issue as I mentioned the amount of moisture is pretty low when it comes time to press/glue. There are numerous vacuum system available http://www.vacupress.com/. You can make your own using a air compressor by reversing a value -it will suck air instead of force air out. Vacuum pressing is an incredibly versatile system for clamping and gluing.

powerbass · #17 06-08-2010, 08:17 AM

I have done a bit of research into this more for curiosity's sake. The initial investment in time, tools and materials is prohibitive if you are only making 1 top, unless you have access to all these tools etc already. The cost goes down the more tops/backs you make. CNC machines are pretty amazing what they can do. I looked into using one for this type of a project. You can place an existing bass top/back into the CNC machine and it will scan the shape and create a digital file which can then be used to make a form via CNC or you could potentially rough shape solid wood plates. Since a bass is symmetrical right/left you could CNC scan only 1 side, saving machine set up time.