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Cello graduation pattern


Jim Bress
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I'm at the point in my cello build where I'm preparing to graduate the top and back plates. The cello is based of the Strad poster for P.G. Rogeri 1717. I've increased the LOB to 746 mm by rounding the neck and tail block areas of the outline. My bout widths are 353 mm, 243 mm, 440 mm. 

https://www.thestrad.com/lutherie/from-the-archive-a-1717-brescian-cello-by-pietro-giacomo-rogeri-/7878.article

My question is in regard to what graduation pattern folks use that make cellos of this approximate profile (also similar to filius Andrea Guarneri celli). Without knowledge of whether the instrument had ever been regraduated, I hesitate to simply try recognize the graduation pattern (without following every dip). The graduation pattern maps I have for cello are from Brian Derber's book, and Sacconi's book. The biggest difference between the patterns to my eyes is for the top plate.

Thanks,

Jim

1263902573_Derbergraduationpatternback.thumb.jpg.0795da4885d440b9fb4350369ec84aeb.jpg2062651678_Derbergraduationpatterntop.thumb.jpg.e2ba9abbf41d687830b147a14d25d3a9.jpg739716361_GraduationpatternSacconi.thumb.jpg.28321181664bd294603ac0eab750676e.jpg

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Crickets... To be clear, I'm not asking about the thicknesses. Rather the pattern of the thickness map. As I said before, the biggest difference seams to be the pattern for the top where Sacconi uses a constant thickness, whereas Brian Derber's diagram has a more complex (concentric) pattern.

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Hi Melvin, Yes the strad poster has grads. Somewhat thinner than J. filius 1710 cello of nearly the same bout widths, but unknown arching. The Rogeri  has quite full archings so the thinner graduations make sense. The top is a bit more of a mystery as there are no grads under the finger board or the tail piece. Although I would guess slightly thicker along the center line. I'm just not fond of guessing (occupational hazard). At present, I'm taking the greater of the asymmetrical thicknesses and adding a couple of tenths of a mm for my first rough gouging.  

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18 hours ago, Jim Bress said:

Hi Melvin, Yes the strad poster has grads. Somewhat thinner than J. filius 1710 cello of nearly the same bout widths, but unknown arching. The Rogeri  has quite full archings so the thinner graduations make sense. The top is a bit more of a mystery as there are no grads under the finger board or the tail piece. Although I would guess slightly thicker along the center line. I'm just not fond of guessing (occupational hazard). At present, I'm taking the greater of the asymmetrical thicknesses and adding a couple of tenths of a mm for my first rough gouging.  

Hey Jim! Something I've done with several grad maps on posters is make a photocopy and then use highlighters to turn it into a "heat map" - so I'd take 5 or 6 different colors and assign value ranges to them, like pink= 4.5 to 5mm, yellow= 4 to 4.5, etc. For my brain at least, this makes it so much easier to visualize what might have been the type of line diagram you are showing from Derber and Sacconi was used for the instrument in question. I'll text you a picture if I can find it. 

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On 5/11/2022 at 12:04 AM, Jim Bress said:

Hi Melvin, Yes the strad poster has grads. Somewhat thinner than J. filius 1710 cello of nearly the same bout widths, but unknown arching. The Rogeri  has quite full archings so the thinner graduations make sense. The top is a bit more of a mystery as there are no grads under the finger board or the tail piece. Although I would guess slightly thicker along the center line. I'm just not fond of guessing (occupational hazard). At present, I'm taking the greater of the asymmetrical thicknesses and adding a couple of tenths of a mm for my first rough gouging.  

My approach would be to listen to recordings of the Rogeri. If you like it then follow the grad patterns ( which I have not seen) .  I'd actually go a bit thicker than the original in most cases l keeping the gradations in proportion aiming at strength and longevity. It's very simple to pull a cello apart and thin it and seldom required.

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2 hours ago, Melvin Goldsmith said:

My approach would be to listen to recordings of the Rogeri. If you like it then follow the grad patterns ( which I have not seen) .  I'd actually go a bit thicker than the original in most cases l keeping the gradations in proportion aiming at strength and longevity. It's very simple to pull a cello apart and thin it and seldom required.

Head slap! :) Yes, I chose the model in large part because of the sound. Not that I would be able to reproduce it, but it's a good place to start. The Cello is by Pietro Giacomo Rogeri 1717

https://tarisio.com/cozio-archive/property/?ID=40712

The player of the cello is Enrico Dindo. One of many YouTube videos. Sadly I have never heard it played live.

https://www.youtube.com/watch?v=9lIMmE6GxwI

I plan on increasing the grads of the back by 50% because it is made of white willow (Salix alba) instead of maple. The ribs are beech. The choice of woods is your fault Melvin because I fell in love with pictures you showed in your bench thread some time ago. :)  The wood is definitely too good for the likes of me, but I'll do the best I can to not make a waste of it.

 

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