Official Luthiers Forum!

There’s always going to be something. Take notes, press on…:)

It's actually a matter of three dimensional geometry. The doming of the back makes the edge rise and fall when you profile it. Also, the taper of the body makes the whole line run at a slight angle, so the surface isn't perfectly perpendicular to the edge. Since the liners don't bend well in the vertical direction you have to twist them a bit to get them to follow the line. This ends up opening the joint on the inside in some places.

Part of the issue has to do with the use of a uniform radius dome. Traditional Spanish classical makers used a straight taper; dressing the back edge off on a flat sanding board. In order to get the curve of the dome along the center line to be smooth they used different radii for the back cross braces, and just trimmed the edge down lightly to the proper angle so that there would be no gaps. This allowed them to use solid liners on the back, which helped stiffen up the back edge while it was being worked on. If you try that with the the uniform dome it's just about impossible to get the liners to go in without any gaps. There's also the problem of getting the dome of the back to look right, avoiding a 'dimple' at the waist. When I work on a solera I usually start out with tall liners, trim them to match the rise and fall of the edge, and then trim them to a uniform height before gluing them in.

With enough clamping pressure you can usually get continuous kerfed liners to be 'close enough'. I prefer to use less pressure, and instead simply cut the liners into short sections that can twisty enough to lie well. I put cloth tapes across the sides every three or four inches, and have the cut ends of the liners over the tape, so I'n using 6"-8" lengths of liner. If you'r careful about lining up the ends it won't show. Try to avoid having a joint at the waist, though.

So THAT's why my kerfed linings bulged. dang, I could learn something every day if I just listened. \\

Thanks!

_________________
Peter Havriluk

I went with binder clips back in the 1970s and I'm still using most of them today. A few months back I got a look at Linda Manzer's shop and was surprised to see uses the binder clips in her shop.

_________________
Rather have a bottle in front of me than a frontal lobotomy