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Right now, precisely, what is the distance between fingerboard plane and top, at the bridge (mention if frets are included). Make sure the FB is well pressed on the neck when measuring, and tell us the thickness of the FB at each corner.

Even if we decide the geometry is OK, a gap between foot and back seen from the soundhole is not the best thing you could show someone inspecting your work!

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Build log

I understand it now. The gap is between the heel and the actual Back - which would indeed indicate more of a negative angle. 3/16" gap is too large to ignore IMO - even though the majority of that gap will be towards the front edge of the slipper foot.

Filippo,

My condolences. The back on the one I've kept for myself had to come off for the same reason. Using the Schramm method, I measured and got my shims together, and then glued up the back without the shims in place. Maybe this is the downside of the method. If the geometry really is fixed by the solera, none of this messing around.

Fish glue is a bear to undo. Waddy's advice is good. I didn't lose any back braces on mine. (I glue braces to the back first anyway, not to the sides

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Jim Kirby
kirby@udel.edu

Don't take the back off, just work out the geometry you need to get the right bridge height/action and taper the fingerboard. A lot of the great builders did it this way, in fact it is the most traditional way of doing it.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Colin. That would only work if the neck was in the same plane as the body. A 3/16 th's gap suggests that it has gone a bit too far the other way, and of course tapering the fretboard will not close that gap between the foot and the Back.
I guess the worst that can happen is a new Back but providing real care and time is given to removing the original it really should be possible to release it and save it. It's just a matter of using the correct technique and approach. Think of it as a real valuable Torres! Tends to focus the mind.
Filippo, you can also glue a 'dummy' back to a 'dummy' slipper foot and practice removing the joint. In fact you can do several to get a feel for what is required. It's much better to do that than diving head first into your actual Back.

Fillippo,
Richard Brune' specifies a 2mm lift at the nut (2mm above the plane of the top) in his specs for the '37 Hauser plus a tapered board. Did David actually specify a neck angle? Or is he relying on the builder to determine it from his method?
That way of getting the angle seems difficult to me. I did it simply by working on a flat solera and blocking up the top with a 2mm thick piece of illustration board shaped to the plantilla under the top with the nut end of the neck clamped to the flat surface to create the 2mm lift. I'm now using a Solera wth this angle built in so I hardly have to think of it at this point.

I would not take the back off but would attempt to fix the back strip issue by popping that section out and fitting a new section which matches the rest.
If indeed your neck and top are in the same plane (which many builders did) a tapered board (say 7mm down to 4) should allow the correct action height (4mm bass 3mm treble) using a slightly taller bridge but you will need to determine the actual measurements.

Fillippo, I hope this helps to illustrate (albeit crudely) what I am talking about.

The built up area of Waddy's form (and mine as well) is to create a drop off at the back of the guitar which enhances the doming (why you scooped out your solera) of the top.
Postive neck angle as illustrated places the neck fingerboard mating surface ABOVE the plane of the top (as illustrated). The flatter this angle is, the more you can taper the fretboard to create it.

The dip at the saddle location is a bit worrying. It should still retain the doming feature, which is a product of gluing the struts into a hollow form. Other than a big change in humidity I can't think why this has happened. It also changes the whole neck geometry thing.

This is interesting, Filippo. I was looking at my solera last night, and I put a straightedge on the neck board, resting on the nut support, and extended it to the bridge location on the scooped out and wedged up lower bout, and it just touches the solera at the point of the saddle location. It's sort of like building flat, but with a "twist", so to speak! The way this works out is, you then add a 7mm fingerboard (at the nut), and a nut slot height of approximately 1.5mm (which clears any fret height). That gives you 8.5 mm which is about the same height of the body of the bridge. Then I taper the finger board and lift the strings with the saddle, and end up with a string height at the bridge of 10 - 11 mm and an action height at 12th fret of 2.5 - 3 to 3.5 - 4 mm depending on whether you are measuring the treble side or bass side. So, what happens is that I have about 2 - 3 mm of saddle above the bridge, depending on the action. I also plane or scrape or sand a slight dip in the bass side of the board starting somewhere near the 5th fret. My strings at the bridge are very nearly level to the fretboard, except for minor variations for action, though I do put a slight dome in the saddle to give a tiny lift to the g and D strings.

If you have a 3mm dome, and an 8.5mm bridge, and a 2 - 3mm saddle, to get the clearance at 12 you are going to have to taper the board a bit(maybe 1 - 2 mm on the bass side to get the correct clearance for good action. This will give you a string height at bridge of 10.5 - 11.5 mm and a bass clearance of about 4mm and a treble clearance of about 3. I'm doing this in my head, so I could be off a little. My figuring puts the treble side pretty close to 3mm without a taper.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I was slow in my post (potty break), and Dave showed it pretty well. Just for purposes of visualization, here are some pictures of my current build's top out of the solera to confirm the doming and taper of the lower bout.

Here you can see the drop off of the lower bout, which begins at about the edge of the soundhole.


Here is a shot with my rough 25' dome measuring device, across the LB showing the side to side dome.

And one more using the 25' radius to show how the tapered lower bout and doming process work together.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Indeed Waddy, the Romanillos solera is much more sophisticated in it's geometry than what I've illustrated and why I liked it enough enough to adopt it for my own building. The solera I'm using still has a little lift to the neck if compared with the sound hole level, but the drop off at the back gives it a much more pleasing and less "folded" look than the simpler arrangement drawn above.

The dip in your top Filippo sounds like excessive dryness to me as well. I'd "bag" the guitar in plastc with a wet sponge to see if you can bring it back up.

Filippo, give us a look at your assembled guitar with a straight edge from nut to bridge location!

Dave, I have about 1.5mm of lift in my neck too. Somewhat less than originally planned for before the wedge was added to the lower bout. I'm at about 1.5mm, which seems to work just about right for the way I'm working right now. I did like you - adding a shim at the nut end of a previously sloped neck. If I change the geometry, I can change the slope.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

0.115 frets included? I think I read something about a dummy FB with the fret height included.

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Build log

Pretty set of wood Filippo. Would have been bad to mess that up!

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Jim Kirby
kirby@udel.edu

Look on the bright side. You didn't trim the top and back yet!
Regluing a top or back is a nightmare because you can never get things lined up perfectly again. But since they weren't perfect to begin with, this should be a piece of cake.

I recommend a clothes iron to heat the surface and get the glue warmed up enough so you can slide a nice wide spatula in there and pry that thing off of there.

Good luck.

Dave