Tap Tones

Well, I am gluing up the instrument. I decided to check the tap tones and weight of the plates beforehand. I used to use a great program for fft analysis called Sakuro8, or something like that. It doesn't work on Apple. I've tried to use Audacity because it will supposedly work on Apple, but I don't see how to get it to do anything. There is a panel, but nothing is active on it. It is merely an exercise in futility. I used my electronic keyboard instead. Anyone know how to get it to work? It isn't user friendly like the Japanese flute program. That one was great.

The back is about 102 grams, and the tap tones are fairly close to each other. The lowest is E3 then C4 and the ring note is Eb4. Almost an octave, with the the fifth a little high, and the octave a little low. The belly is harder to find the notes for. The low note is low; Bb2. Then the next note comes slightly more than an octave up at B3, so it is a semitone lower than the back there. The ring tone is elusive. I hear different notes depending on where I hold it. I hear a cluster of notes: E4, F#4 and A4. None of them particularly ring like the other two do. The belly is 75 grams.

Using the formula to gage stiffness we have 294 squared times 102 = 11.1 and, 370 (I used the F# a fifth up from the B) squared times 75 = 10.3.

They both seem to flex about the same to me. The edges are quite flexible, but the center is quite stiff. Maybe I could have gone thinner on the belly. Let's see what really stiff can do.

Edge Method

I generally use the edge method given by Roger Hargrave in his article on the Working Methods of Del Gesu. I found it originally here: http://www.vsa.to/index.php?option=com_content&view=article&id=76:classical-edgework-by-roger-hargrave&catid=20:selected-articles&Itemid=140
That is what I used for this one. It would have worked if the purfling was 2.5-3 mm tall, and if my platform was flat; but it wasn't, and the purfling is only 1.8 mm. After fixing it up, I have come up with some alterations to the method if you are making a model with thin edges. Here is the plan:

What this does is make the platform lower, while keeping the edge at about 4.5 or so. Here is what I was dealing with:

And this is how it ends up. I still need a little work on the edges, but it looks much better than it did.

Bite the Bullet

I am going to replace a lot of the purfling on the back I'm making. The model has thin edges, and a thick center strip, and the thin edge combined with short purfling didn't work. When it starts getting thin it looks shabby, even if it is still there. The belly must have had a taller piece of purfling, and it was stuck in the groove within a mm or two, and not .5 mm, and I stayed somewhat further from the purfling when bringing the recurve in, and I may have cut the back a couple tenths of a mm thinner.

The bottom line is: the belly looks ok, but the back needs some TLC.

Cutting the groove back into where it was glued, and may still be glued in is no picnic; but I see no way out. NOt all of it will need to go, but much of it will. I am thinking of making my own purfling. I've thought of doing it with thin strips of wood, that aren't glued together. I've done that, and it works fine. But I think it may work better to glue the strips together in the groove, using fish glue, or casein; and then pulling them out, and re-gluing like normal purfling. The hardest part of loose strips are the corners.

Well, I have work to do.

How Long Does It Take

I'm always asked how long it takes to make a violin. I don't know. It doesn't take as long as you would think. I'm getting faster, but I never kept track of time; it's a lot of bother, and I'm not trying to figure out how much an hour I'm making on them.

The violin I'm making for the VSA was going along fine. Then the back curled up on the ends like a potato chip! The wood had crazy grain, and I was using water on it to make the planing easier. I tried to flatten it out by getting it wet and clamping it to a board. That didn't work. The next day I took it off. It looked somewhat better, but flexing it I heard popping noises; it was pulling away at the center seam, I ended up with a 2 mm wide gap on the bottom third of it.

I split it and re-joined it. I glued it up. Both of those were not easy to do. Then I noticed that the button was about 2 mm off center, and naturally it was off on the side that was cut about 3 mm closer to the centerline. I can't use it for this; maybe for something else, but not for a competition. The new one I made has a lower arch, and a higher tap tone, so maybe it was the one I was meant to use.

Our grandkids, and daughter, and son in law were coming up, so I knew I wouldn't have time to work on it. I had another back glued up, and started on it. I kept track of time and I got it down to the same weight (130g) as the other was when it conked out on me in 9 hours. In 3 more hours I had it ready to clean up the outline, and put in the purfling groove. So 12 hours to get it semi-finished and at 112 grams. Is that a decent time? I don't know.

Today I wanted to get the groves in. I haven't made the fixture for the rotary tool yet (I need to get an 18 mm tap), so it is a job for a marker and a knife. I used my magnifier, and it made a big difference. I don't see anything that looks terrible, I'll know more when I get the purfling glued in. I found a thin flat file that works well for flattening and trimming the groove to size. It took 2 hours a plate to get them done. Is that a decent time? I don't know.

I do know that 4 hours of knife time gets my hands sore!