Laminated Back and sides thickness

[aqualibguitars]

Hello friends
Happy new year to all of you...
friends after building about 15 guitars im thinking of building classical guitar on ramirez bracing pattern from
0.5 mm veneers.
today i made the laminated sides from 4 layers of 0.5 mm and glued them with titebond. they are pretty well rigid and strong.

now i want to glue the back veneers. so want to know the thickness of back
shall i glue 5 sheets of 0.5 mm veneers to make 2.5 mm thick or 3 layers of 0.5 + 1 layer of 0.7 mm to make 2.2 mm thick.

can i glue the veneers on flat granite surface and later dome with the bracing?
or should i glue them in radius dish to get the dome ? if yes how it should be glued as i dont have vacum clamp..
will the radiused back will require lighter back bracing??

sry for asking too much as its 1st laminated back and sides guitar.
Thanks in advance

[Ned Milburn]

I can understand laminated sides...

But why a laminated back??

If you use 5x 0.5mm, it will be thicker than 2.5mm when finished due to glue thickness (4 layers).

If I were doing this, I'd make a male/female form of my back contour, and glue it to shape.

[aqualibguitars]

so shall i make 4 layers of 0.5 + 0.7 mm to make about 2.2 mm
or 4 layers of 0.5 mm?

[redir]

I think I would just use 4 layers of .5 to get roughly 2mm back. That would be too thin for a solid wood back but might be ideal for a laminated back that would be heavier at the same thickness.

[Truckjohn]

A laminated back will be very stiff - especially if you laminate the dome into it.

Without having it in hand so I could flex it myself - I would probably want it a bit thinner rather than thicker.... And then be able to add another layer of it needed it.

[aqualibguitars]

thanks mr. redin and truckjon
is it that similar thickness if laminated more stiff than solid?
i will try 4 layers today and will let it cure for 1 week and check the weight and thickness. and will decide to have another layer o no

i was thinking of making 4-5 domed braces of about 1" thick and use them to clamp the veneers on the radius dish. will it help ?

or i glue them flat and later radius them?

[charles Tauber]

Since you appear to be unaware just how much stiffer two thin pieces are when glued together, I suggest you perform a simple experiment with scrap materials.

Take two scrap pieces of wood the thickness you intend to use for each layer. Flex each of them separately and then stacked. Observe how stiff they are. Then glue the same two pieces together. When dry, repeat your flexing. Observe that they are considerably stiffer than either piece alone, or when stacked. Observe how difficult it is to bend the glued lamination to conform to an arched shape.

Do that, and you'll have direct experience - without wasting a lot of wood or glue - on how stiff a glued assembly will be and what success you might have in pressing flat laminations into a curve after the glue has dried.

[redir]

There is nothing wrong with a super stiff back if that is what you are going for. Those old Guild's with the non-braced laminated and arched backs sound good, for example. But those were probably laminated on arched molds so it would require some tooling for that.