Ribs, 3 Ways

I get my ribstock off the backs. I have had a couple backs that came with a separate piece for ribs, but usually I saw them off the extra stock on the back. I don't know if that's what most people do. So I have 3 backs cut out, but I just started on the ribs. Here's what I have:






The first is the way I usually do it. The stock was thicker than needed, but not any wider, so a long rip cut left me with this. It isn't all smooth yet, and it looks like it will be "fun" to bend.






Then the one I started the other post of long rip cut. It was extra wide, 33mm or so extra wide so there was enough left over after roughing out the outline to get a set of ribs too... I think. It might be a tight squeeze, but there should be enough for a violin. I left the tabs on to clamp it while roughing some of the stock off.






This is the last one. I looked at the leftover from the last one I cut out. That one has the light/dark luminous wood. If I'm careful there is enough to make another violin! This one I'll flip the one side over so it is easier to carve. I won't be bookmatched, the thick area was on the outside, but it doesn't look bad, the wavyness seems to work. The light/dark still won't match, something about it just won't let it happen, but at least you can carve in the same direction on both sides. There was enough left at the big end to cut 2 chunks 33mm wide for ribs.

Drawing lesson

Danhux asked me how I got dimensions for my drawing of the Guadagnini violin. Well, I kinda, sorta, made them up, and kinda sorta scaled them off of photographs, and kinda sorta used ratios that are used to draw up outlines on all violins. Each maker may use different ratios, or different starting points. The fastest and best answer to Dan might be to buy a Stad Poster. That wouldn't be a bad idea, I might suggest The Titan (Titian) Strad and then you could follow the same arching I used on the one I made at the beginning of the blog. It will give all the measurements you need except the neck and fingerboard, those are just made standard. Many people will recommend that you just make the mold for the ribcage by tracing the outline of the back on a 1/2" piece of wood, and cutting it 3.5mm or so in from the line. This will allow for the overhang (2.5mm or so) and the 1mm thick ribs.

Yeah, that will work. But it wasn't the way they did it. And your outline might end up pretty whomped out. The Titan is a good poster, but it is not very symmetrical. There aren't many old violins that are. It's from the way they are constructed. The ribs are build on an inside frame, and when they are released from the frame they may not stay where they were. The outline was traced on to the back and belly using a washer to get the overhang, and then they were cut out. There could be quite a difference in shape. The frame, or mold was made fairly symmetrical, so the ribs started out symmetrical. Why not start out the same way?

Well I thought my mold for the Titian, (I thought it was Titan, Titan sounds better, who makes this stuff up?) was off. It was another mold for one I started a long time ago. The delGesu is OK too, it's a little different. But here's a lesson on how to draw up a P mold for a Titian Strad.





Draw a centerline, mark the center of it, and then mark it out 173.5mm from the center to make it 347 long. Mark it again at .8 and .6 of the length from the top. That will mark the lower bout and lower corner. Mark a point 4/7 of the lower corner for the upper corner. The point for the upper bout can be located where the distance between the bouts will be .618 of the total length. Yeah, you have to do some math for that. That gives you the lengths.

For the widths you can use 160/101/200. I only draw one half, so divide them in half. I used 78mm and 88mm for the upper and lower corners. For the arcs at the top and bottom I chose a point 5/8 up from the bottom. That point happens to be the apex of the triangle drawn between the f holes. A line 5/8 down from the top bisects the lower holes.

You can find radii to make the shape right, but you'll have to have the poster to make it to your liking. The poster also give every measurement you need to make it. Thicknesses, f hole measurements, arch height vertically and horizontally. It also has the ct scans of the arching and ribcage (thats where you want to check your drawing.

The one I just drew up is pretty close to my mold. The f hole at the bottom could be pushed out a mm or so further, but it's pretty close. It's closer than the one I made!