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fingerboard thickness violin


violins88
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The fingerboard is not a cone either. The radius is the same at both ends and the surface between those ends is not a uniform curvature. This, I think, is the point both David and I were making.

Also, if you slice off the curved part of the fingerboard from trapezoid it sits on the difference from one end to the other end is more like 3.6 mm not 2.25 mm. This is what the Sagitta calculates for you.

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I like Michael Darnton's example of the cone shape of the fingerboard is like theshape of the containers Rolled Oates come in, but modern times has made that more difficult to find.

So instead here is the best I could do.

 

kraft_parmesan_1.jpg

 

I like it better than Rolled Oates because of the Italian connection! ;):)

 

The difference in thickness from the 'nut end' to the' bridge end' of the fingerboard is around 2.25 mm.

A cone will have a smaller radius (rounder) at the nut and larger radius (flatter) at the bridge end. This is the worst shape for a fingerboard. See post 16 above.

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I just shot a fingerboard, working more carefully to my template in the centre than usual. I have measured the scoop and I find I have a fairly even progression from shallow to deep. Now I'm totally confused, as I see the merit in David and Curious One's arguments, but I can't see why my own visualisation of it (post 20) should be all that wrong either.

 

Anyway, as long as it works properly!

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I just shot a fingerboard, working more carefully to my template in the centre than usual. I have measured the scoop and I find I have a fairly even progression from shallow to deep. Now I'm totally confused, as I see the merit in David and Curious One's arguments, but I can't see why my own visualisation of it (post 20) should be all that wrong either.

 

Anyway, as long as it works properly!

I think if you did the calculations of David's point I don't know how much rounder the board is in the middle but it is rounder and I agree. I think David is making more of a point about theoretical conceptualization not practical manufacture. My point is more about method and production of a fingerboard. The change af curvature in the middle of the board is the result of the scooping. You can certainly use your template in the middle of the board as a visual guide that everything is transitioning well but it should match as it does at the ends. If you try to match the radius at all three points the scoop will be off. How much? Probably not much but off.

It is my experience that the correct radius at the ends and a perfectly formed scoop both in shape in amount is the key to success here.

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I have now determined the problem for my fingerboard. I had ASSUMED that the factory curvature was correct. The sagitta formula would not work out right. It turns out that the nut end of the fingerboard has a much smaller radius of curvature than 42 mm. Thus the middle was 8.2 mm high when the sides were 5.5.  Whereas the correct numbers is closer to 7.25.

 

And thanks again to all who have replied. Once again, Mnet has increased my understanding.  I always get very excited about how the violin will sound when first strung up. Can't wait.

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Once again I appeal to the great resource of Maestronet makers.

 

I am preparing the fingerboard for violin #16.  At present the nut end thickness is 8 mm. Thickness of the other end is 5.0 mm, with most of the scoop prepared.  I read Schleske's page here, which suggests the fingerboard main resonance in the free state should be 1.67 * B0

 

So if B0 is 270Hz, then the fingerboard frequency should be about 450Hz. 

I measured the frequency of my too-thick fingerboard at 393Hz. Already too low. So the fingerboard is thick, but already too low in frequency.

 

Should I keep thinning it. Right now it weighs 73.7 grams.

 

Thanks in advance.

 

 

violins88,

 

It took a look at Schleske's FB tuning page. The formula 1.67 * B0 is only a prediction what the B0 could be with his own more or less standardized necks/scrolls density.

 

If you are still interested in tuning, a better formula to predict B0 is: (B0 without FB + free FB mode)/2,5

 

393 Hz is quite low. Shortening the fingerbord, hollowing out the underside 1,5 cm at the end, and removing wood from the sides rises the frequency. For example If the B0 without FB is 240 Hz, a FB of 393 Hz would give a predicted B0 ~ 253 Hz.

 

Others have already given you info that your FB is a little thickish and heavy.

 

Peter

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Once again I appeal to the great resource of Maestronet makers.

 

I am preparing the fingerboard for violin #16.  At present the nut end thickness is 8 mm. Thickness of the other end is 5.0 mm, with most of the scoop prepared.  I read Schleske's page here, which suggests the fingerboard main resonance in the free state should be 1.67 * B0

 

So if B0 is 270Hz, then the fingerboard frequency should be about 450Hz. 

I measured the frequency of my too-thick fingerboard at 393Hz. Already too low. So the fingerboard is thick, but already too low in frequency.

 

Should I keep thinning it. Right now it weighs 73.7 grams.

 

Thanks in advance.

Only low if you are trying to match the A0. Otherwise 253hz seems fine to me.

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I bet I am the last person to realize that this scraper 650.jpg

the one on the left, has a curve of exactly 42 mm. Just right for checking your violin fingerboard. My stock fingerboard had a much smaller radiused curve than this. I have had this scraper for 30 years. Finally discovered its use.  Better late than never. So now, the fingerboard, at the small end is 7.25 mm high and 5.5 mm at the edges. Just right. And the fingerboard now has a constant radius, (more or less, due to the scoop), of 42 mm.

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The Karl Roy book, (free page here)  which I think is a very valuable resource, seems to have an error with regard to fingerboard thickness. For 4/4 violin, it shows 9 mm as the thickness of theend of neck". Does this mean the narrow end of the fingerboard?  My calculation, assuming the side thickness is 5.5 mm, gives 7.25 mm for the end of board thickness.

 

Maybe an addendum has been issued, I don't know.

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The Karl Roy book, (free page here)  which I think is a very valuable resource, seems to have an error with regard to fingerboard thickness. For 4/4 violin, it shows 9 mm as the thickness of theend of neck". Does this mean the narrow end of the fingerboard?  My calculation, assuming the side thickness is 5.5 mm, gives 7.25 mm for the end of board thickness.

 

Maybe an addendum has been issued, I don't know.

Appendices2 fom Karl Roy's book reads "Thickness: End of Neck" 4/4 violin as 9 mm.

 

This strikes me as being the end of the neck where it meets the neck root.

So you end up with a measurement somewhere between the Nut end and the Bridge end of the fingerboard.

This would mean that the measurement would be taken very close to the middle of the fingerboard.

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Appendices2 fom Karl Roy's book reads "Thickness: End of Neck" 4/4 violin as 9 mm.

 

This strikes me as being the end of the neck where it meets the neck root.

So you end up with a measurement somewhere between the Nut end and the Bridge end of the fingerboard.

This would mean that the measurement would be taken very close to the middle of the fingerboard.

Yes, after looking at it again, I agree with you.

 

Thanks

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I'm curious if anyone can give a reason for this particular measurement?  Not the number itself.  Maybe it's to make sure the maker hasn't left too little meat in the process of shaping the board.

My guess is that Karl Roy does not give numbers for the amount of scoop under the strings, but following the 41.5 mm radius template at each end, with 5.5 mm edges, and 9 mm middle thickness accomplishes the same thing.

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I bet I am the last person to realize that this scraper 650.jpg

the one on the left, has a curve of exactly 42 mm. Just right for checking your violin fingerboard. My stock fingerboard had a much smaller radiused curve than this. I have had this scraper for 30 years. Finally discovered its use.  Better late than never. So now, the fingerboard, at the small end is 7.25 mm high and 5.5 mm at the edges. Just right. And the fingerboard now has a constant radius, (more or less, due to the scoop), of 42 mm.

John, do yourself a favor and round off those sharp corners. When scraping the ridges off a planed fingerboard in situ, there is the potential to damage the varnish on the top or the side of the pegbox.

 

I actually cut my scraper like that into three pieces, one concave for fingerboards, the convex piece for inside plate scraping, and the center squared piece for undetermined future use.

 

This concave scraper is also very useful for finishing off the neck heel and handle too.

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John, do yourself a favor and round off those sharp corners. When scraping the ridges off a planed fingerboard in situ, there is the potential to damage the varnish on the top or the side of the pegbox.

 

I actually cut my scraper like that into three pieces, one concave for fingerboards, the convex piece for inside plate scraping, and the center squared piece for undetermined future use.

 

This concave scraper is also very useful for finishing off the neck heel and handle too.

Bill,

 

Thanks for that advice.

 

John

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