Making Solera

[Steve.Toscano]

Hey all.

I primarily have been making falcate braced, spanish heel, steel strings in a solera (with unknown radius dome) that i borrowed from a mate, mate and solera have now moved to Alice Springs, solera is in storage.
So I'm embarking on the journey that is making my own solera.

So far i have a completely flat made from 18mm marine ply cut to shape and slotted for moveable side supports.

I'm about to dome out the lower bout area around the bridge which brings me to the following questions:
1) Should I dome all the way to the edges (where sides will meet top) or dome to 10-20mm short? Advantages/disadvantages of both?

2) I'm aiming for 25foot radius and will be doming entirely by hand - planes/chisels/scraper. What's the best method to measure this? I've used the cut out the radius on a piece of thick paper before, is this still the preferred method?

3) How exact do i have to be to the 25foot radius of the dome? I'm guessing i dont have to strive for perfect symmetry. I will clamp top braces in the same solera.

4) Based on a 25foot radius and a 644mm scale length what would be the approx shim size at the nut to get the right neck angle when glueing the back on? Is there a way to calculate this? Or am i left with having to "guess and check" - not that keen to resetting the neck angle. In the last solera it was exactly 1 paddle pop stick at the 5th fret but the dome radius was unknown on that one.

5) I've never made a classical before, can i used the same solera (side supports are moveable and will accommodate this). Same dome? Same neck angle if the scale length is the same?

Thanks in advance

Cheers
Felix

[johnparchem]

I can answer some of the questions as I have made a solera for a classical ..

Hey all.

1) Should I dome all the way to the edges (where sides will meet top) or dome to 10-20mm short? Advantages/disadvantages of both?

I left the dome short a bit, but I do not have a good reason why

2) I'm aiming for 25foot radius and will be doming entirely by hand - planes/chisels/scraper. What's the best method to measure this? I've used the cut out the radius on a piece of thick paper before, is this still the preferred method?

Your way with paper will work I just calculated the sagitta of a arc across the dome, Drilled a hole in the center that deep and by hand planes\scraper\sandpaper worked a dome down to that depth. A cut out radius will help keep it even.

3) How exact do i have to be to the 25foot radius of the dome? I'm guessing i dont have to strive for perfect symmetry. I will clamp top braces in the same solera.

I was not perfect but pretty good

4) Based on a 25foot radius and a 644mm scale length what would be the approx shim size at the nut to get the right neck angle when glueing the back on? Is there a way to calculate this? Or am i left with having to "guess and check" - not that keen to resetting the neck angle. In the last solera it was exactly 1 paddle pop stick at the 5th fret but the dome radius was unknown on that one.

On a classical the neck needs to tilt the opposite way because of higher typical action on a classical and lower string height over the top at the saddle. Typically the nut is 2 mm above the plane of the top. Some solera makers tilt the neck part of the solera back a bit hinged at the neck body join. I seen others where they will use a shim but under the top at the body join not the fret board position. If I am thinking straight about 1 mm.

5) I've never made a classical before, can i used the same solera (side supports are moveable and will accommodate this). Same dome? Same neck angle if the scale length is the same?

If I am understanding side supports and they can move they should be OK. The dome could be OK but the neck angle should change, clever use of shims might accommodate both SS and classical .

Thanks in advance

Cheers
Felix

[Steve.Toscano]

I can answer some of the questions as I have made a solera for a classical ..

4) Based on a 25foot radius and a 644mm scale length what would be the approx shim size at the nut to get the right neck angle when glueing the back on? Is there a way to calculate this? Or am i left with having to "guess and check" - not that keen to resetting the neck angle. In the last solera it was exactly 1 paddle pop stick at the 5th fret but the dome radius was unknown on that one.

On a classical the neck needs to tilt the opposite way because of higher typical action on a classical and lower string height over the top at the saddle. Typically the nut is 2 mm above the plane of the top. Some solera makers tilt the neck part of the solera back a bit hinged at the neck body join. I seen others where they will use a shim but under the top at the body join not the fret board position. If I am thinking straight about 1 mm.

Cool. I'm thinking for a classical here that i could just use a sheet of 400gsm paper which is around 1.2mm, place this between the entire body part of the solera and the top of the classical. This would 'lift' the body by 1.2mm and yet keep the same dome.
Obviously not use a shim at the neck/nut as i would with a SS build.
The solera will primarily be used for steel string builds anyway.

[jeffhigh]

Typically a solera is scooped out to about 2-2.5mm depth, just in the lower bout.
Leaving it flat at the edge makes it easier to fit lining blocks
If you taper it down to 2mm at the nut it will be usable for classicals and you can just shim it up for steel strings
You need to use a straight edge to measure your dome and then calculate neck angle
It does depend on desired action height, fretboard thickness, fret height, neck joint location and dome height ,so a simple answer is not applicable. I use a spreadsheet.
Mostly I build with a radius disk and a bolt on neck but I currently have one slow student building a classical on my solera.