Violin Forum/Message Board

[hillyer43]

I have fitted several violin bassbars and a few tonebars on archtop fretted instruments, but I'm still very slow and not very good at it. I try very hard to achieve a smooth inner surface on the top plate. I then temporarily glue 4 small locating blocks either side of the bar position and gradually fit the bar using the sharpest possible chisel to remove the chalk-marked areas after chalk-fitting the joint. I only move the bar 1-2mm end-ways when chalk fitting. When I get to a 60-70% fit, I use a very sharp scraper on the high spots.

It takes me many hours to get a fair fit, but I've never yet managed a 100% result. I suspect I'm doing something wrong, or at least inefficiently and would appreciate some guidance from more experienced makers. How long does it take for a professional to fit a bar?

[Michael Darnton]

I can do it in about 20 minutes, but I've fit maybe 400-500 bars. A reasonable time is around 3-4 hours. The key is to NEVER cut a place you aren't absolutely sure is touching. Don't think that you'll take an extra cut on someplace you think will put you ahead; just cut what you're sure touches. If you're not sure, put it off until you are.
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[hillyer43]

Mr. Darnton...many thanks. A 20 minute fitting time is certainly something for me to aim at ! I'm partly relieved at your suggestion that 3-4 hours is a reasonable time. I've just got the glue drying on a bar that has taken more than 6 hours to fit. I pencil round the marked chalk on the bar glueing surface, then with my sharpest chisel angled at about 45 deg., use the finest slicing motion I can manage to pare the chalk away with (hopefully) the finest of shavings. I'll definitely be more careful in future as you suggest, not to get the chisel to cut places that aren't touching. I'm sure this is one of my problems.....my chisel control needs improvement I'm sure. I suspect that scraper use also risks rounding the bar edges as well, but it does seem to work for me.

[actonern]

Hi Michael:

I'd be interested to know if you initially trace the cut lines on the bar with some sort of compass like tool or just go at it with the experience of knowing roughly how much to hog off the ends and then slowly refining till it fits...

E

[Michael Darnton]

I don't do any scribing or anything. First I take a big knife and shape with large cuts until I'm forced to make smaller and smaller cuts. At some point I switch to a tiny flat plane for the finishing. I use my eyes as much as possible, going to chalk only at the end. The violin maker's basic tool choice rule is to use the biggest tool you can, for as long as you can control it easily. Also, don't rely on chalk too much: use eyes until they can't do the job.



I use a very small (8mm wide blade, I think) flat fingerplane with a shim under the blade to close the mouth down. The blade is sharpened for minimal clearance above the wood so that it doesn't tend to dig down into the wood. The edge is bowed, across, just a little, so I can snick out just the little bit of wood I want.
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[actonern]

It would all be so much simpler if it weren't for that little reverse dip section on the f hole side of the bar, in the middle!

[Jacob]

[actonern]

Hi Jacob!

Not a source of "worry." Just more work than a straightforward uncomplicated bow shape. I've made all my recent violins strictly in accordance with the c cycloid profiles, and I've not made one yet with that method that didn't have that gentle little angled "concavity" mostly on the outside f hole side of the bass bar close to the f hole...

Best regards,

Ernie

[Jacob]

[actonern]

In the mid bouts? Really?

Let"s say the bottom of the trough is right on the purfling (in other words as far apart east and west as you'd ever practically want to go). A cycloid will still produce the effect I'm describing... and I'm talking a Del Gesu model with mid bout widths of 112- 113 mm... That's a wide violin!

A narrower waisted instrument, or one that has the "trough" further in from the edge even more so... do you disagree?

E

[fjodor]

I've also had the same experience as Ernie regarding "a dip" in the bassbar at the upper f-hole area when using cc arching.
(admittedly not as wide as Ernies model in the c-bouts, but the low point of the cc-curve being at the purfling)

[Jacob]

[actonern]

I look forward to Michael's comments too.

My impression of the cycloids used in Cremonese work is that there isn't the flexibility of choice you're describing.

As far as I've seen, the circumference of the "circle" for any cross arch point is defined by the distance from the "trough" or exact bottom of the arch on one side of the plate to the same point on the other. At least that holds true for the comparisons I've made...

So, for example, if the bottoms of the arch across the widest point of the top bout are 150 mm apart, that is the circumference of the circle for that cross arch point, and the little hole is set at a distance from the centre axis established by the long arch height at that point. Using this approach, there will naturally be a "tighter" radius to the trough in the mid bouts than the wider upper and lower ones.

I'm happy to be corrected... just conveying my understanding to date.

Best regards,

Ernie

[Michael Darnton]

I guess there's a lot to say about the subject, but most direct at the moment is that I've never seen a "real" violin that didn't have the dip in the bar in the center.

As far as the dynamics of how the various curves were mapped out, I'm pretty sure there's a plan to it, and I think I know what it is, but I've been too lazy to do the necessary work to see if I'm right. :-)
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[Jacob]