Violin Forum/Message Board

[Michael Darnton]

I did a little drawing to explain how the common cello board template is used. In order to have the template fit down the whole length of the board, and yet to have the board edges a consistent thickness all the way from end to end, you have to twist the template as you move up the board. The drawing shows the template positions at the widest and narrowest ends of the board:

[violinarius]

I never thought about that! Thanks!

I have run across in reading into various radii for cello fingerboards, 64 mm and 70 mm mostly.
Is the 70 mm for a non-Romberg, and 64 mm for a Romberg? or visa-versa?
Thanks!

[Chris Knowlton]

Nicely done. I don't expect to make a cello anytime soon but I enjoy reading about them. Your drawing shows the varying shape very well.

Does a cello fingerboard incorporate scoop?

Chris
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[Michael Darnton]

Yes, cello boards need scoop, especially under the C string, much more than the others.

[MANFIO]

Good! Michael, do you use templates for violin and viola fingerboards too?
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[Michael Darnton]

I have the usual set of templates. I always use them when I'm doing something from the beginning, but if I'm dressing a board for a customer and there are no complaints about the way the board is working, I will stay with the way it is. I don't believe in removing large amounts of wood simply to make things my way, without some good reason.

[MANFIO]

Thanks!
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[violinarius]

In trying to answer my own question, about various radii for the curved section of the fingerboard, I too did some drawing ( when in doubt get the pencil out ). I too drew out the diagram the Michael did, and found out that the radii used in Europe, (r=60 to 64 mm) fits just slightly better than the West Coast radii (r=70 mm), at the nut end.

The width of the fingerboard at the nut is approximately 32 mm, and at the bridge end, 64 mm.
The width of the Romberg is approximately 9 mm at the nut and 22 mm at the bridge end.
So we get a change of 2 times in fingerboard width, but 2.444 times in Romberg size.

Something has to give, since scale-wise the two measurements are changing at a different rate.

If you maintain the angle of 30 degrees or thereabouts for the Romberg, then the thickness of the Romberg flat at the nut end, which means keeping the template level, would have to be reduced to something in the area of 4.5 mm, which won't work very well for the player.
This is slightly less reduced with the radii of 60 mm or 64 mm.

The center of the radius, for the curved section of the template, is being shifted as you go up and down the fingerboard, when you do the 6.5 degree tilt. Since the radius stays the same, this is a *cylinder section*.
What does not change is the angle of the Romberg, relative to the cured section, since this angle is fixed with the template.

The flat on the Romberg is actually twisting, since it is following the *section of a cone*, like Michael's oat cereal box.

From a playing aspect, I suspect that this twist in the Romberg works because the player is pulling the string down more at the bridge end of the fingerboard more than the nut end.

I also suspect that while the tighter radius fits better at the nut end, the larger radius works better at the bridge end, which is where the two sized templates vary the most, because a wider section of the circle is being used.

The next fingerboard I do I might try using my European template at the nut end, and the West Coast template at the bridge end, so that the curved section follows the cone principle, rather than the cylinder section, so it's the same as the Romberg section. But hey if it ain't broke .....