Violin Forum/Message Board

Michael Darnton · Posted: Sat Oct 04, 2014 9:09 pm Post subject:

In the 90s I was visiting Beare's in London. Their head restorer had been the teacher at one of the UK schools. Looking over his shoulder, I ran my finger over one part of the arching of a Strad he was working on, without saying a thing. He said "Yeah, when I think of all the students I taught wrong!"

It's easy to see if you have access to enough of the instruments to get a handle on what should be there, which is something that just about no maker is able to do unless he has worked at a large shop that handles those instruments regularly. Even then, you have to pay attention, and you have to be a good observer. That gives you a slight edge, but you still have to take it and do something with it.

A few years ago a good instrument and its "bench copy" visited my summer class in California. After the show-and-tell, several of my students came up, on their own, and commented on how the copyist, who'd had the instrument in his possession while making his, had missed a very crucial aspect of the arching.

It's "easy" to drive a car, but you still need to learn how to do it, right?
Easy to see does not mean that everyone sees.
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Chet Bishop · Posted: Sat Oct 04, 2014 10:24 pm Post subject:

Well...this is a little frustrating. I am assuming that this is something not touched upon when I had my one chance to come to Claremont.

And, it looks as though it is something that will only be discussed in veiled terms unless one comes back again. I am sure I must be "doing everything wrong", but I am not sure I can afford another trip to L.A.

If it is something that can be learned here on the forum, I would like to partake. If not, then...I guess I don't foresee learning it any time soon. Too bad...

Is there a place within the forum that I can go to see this? I have tried to keep up, but I must admit I haven't a clue what "everyone is missing", and feel kinda sad to miss out.
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Michael Darnton · Posted: Sun Oct 05, 2014 9:54 am Post subject:

It all boils down to cycloid cross arching. Not hanging chains, circles, catenaries, or various freehand ideas. Very simple and straightforward; very difficult for people to want to accept, apparently.
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Chet Bishop · Posted: Sun Oct 05, 2014 11:17 am Post subject:

So...if I do the hypo-cycloid curves for all the cross arching, (how many? every centimeter like Sam Compton, or just the usual five or six places?), will I most likely produce the thing you are talking about, or is there a trick to it that will be missed without further explanation?

I completely accept the concept, but wonder whether I really understand it. I have followed with interest all the talk about curtate cycloid curves (hypo-cycloids) because I knew about them before I ever tried to build a violin,. and am completely convinced that you are correct. (Incidentally, hyper-cycloids are interesting, too, but useless for violin-making...they make a loop outside the curve, momentarily moving backward at the bottom of each cycle. A dot on the outer edge of a railcar wheel does this.)

I guess I need to cut out some wheels. Thanks.
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Michael Darnton · Posted: Mon Oct 06, 2014 1:49 pm Post subject:

I would say that you don't need to understand it only do it :-)

I'd you Google violin curate cycloid smann you will find the software I use to generate my templates.
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actonern · Super Member Joined: 15 Aug 2007 Posts: 444

I find that following C. Cycloid cross arches has the effect of making the top f hole slope downwards, when looking at the instrument sideways to observe the slant of the f hole stems

I know that lots of cremonese instruments share this feature, but Strad f holes seem, in the main, to stay parallel with the edge work, or sometimes even seem to slightly climb upwards.

Would this mean something else was going on in the arching to make this happen?

E

Michael Darnton · Posted: Mon Oct 06, 2014 4:01 pm Post subject:

I'd you think in terms of carving the holes from the side via tiny arcing changes at their edges, you can achieve any appearance you wish.
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actonern · Super Member Joined: 15 Aug 2007 Posts: 444

From your examination of Stradivari's instruments, Michael, have you made any observations about his having adjusted the arch through the mid bouts in order to preserve a parallel orientation of the f hole slant to the instrument edge?

E

ctviolin · Posted: Tue Oct 07, 2014 11:21 am Post subject:

so, just to get this idea straight in my own mind, Michael, you'are talking about the top and the back CROSS arches, both?
Right?
And the long arch, is that starting out life a segment of a very large circle?
I have my tops slightly off center this way, as the highest point of this top plate long arch (for me) is directly under the bridge - for the belly, that is - and ifor the back, its in the center of the plate longitudinally.

I know that once the violin has been strung up, depending on what's going on inside, and with the different thicknesses and different woods used, that there may well be very different results, with regard to the long arch, and its bending due to neck/tailpiece pressures and strains, plus the downward force of the bridge on the belly and the soundpost pressure on the back.

But my question to you has to do with the long arch before stringing up...

I understand the cross arch methodology everyone here is posting about.
And I believe that we've spoken of this aspect of arching before (the long arch and its character), but I no longer remember what the final decision was - or if there ever was one?
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ctviolin · Posted: Tue Oct 07, 2014 11:23 am Post subject:

Sorry if I'm changing the direction slightly...
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Michael Darnton · Posted: Tue Oct 07, 2014 11:44 am Post subject:

Michael Darnton · Posted: Tue Oct 07, 2014 11:45 am Post subject:

Craig, you can't have a circle if it's highest at the bridge.

I don't make the top and the back the same, but if I did, I would make them the same. :-)
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ctviolin · Posted: Tue Oct 07, 2014 11:59 am Post subject:

ctviolin · Posted: Tue Oct 07, 2014 12:10 pm Post subject:

OK, now you've got me thinking back to when I first designed the top arch, arch...
If I remember correctly, for the high point to be directly under the feet of the bridge, I had to stretch one segment out of circular into essentially an ellipse...

It's been a while since I made a complete violin (probably at least three years -the damned stroke and all of that mess) and much of the what I used to do essentially routinely, I've had to re consider or re invent.

Please let me reconsider the problem... I did have it all figured out at one point but much of this stuff has eluded me recently.
Ahhh life, what fun, huh?
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