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Dennis J

Arching Templates

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2 minutes ago, David Burgess said:

Right now, it sounds like you are endorsing something much less complex than your past multiple pages of design theories.

Explain the unfamiliar in full detail can look much more complicated than it is.

The complicated explanations amount to the simple one above.

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7 minutes ago, David Beard said:

Explain the unfamiliar in full detail can look much more complicated than it is.

The complicated explanations amount to the simple one above.

Except when they don't.

You been smokin' a bit o" pot? ;)

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So, take that simple version and add some detail:

1) The radii observed from the channel bottom aren't just random.  Like with ever other f'ng detail, the old Cremona work places and sizes everthing by proportional relationship between parts.  So the radii for these curves are proportioned from the rib height.  

2)  The test for the fall depends the points you choose to test between.  The top point for testing is chosen at or a little ways out from the center line.  The low point choice varies.  Always a logical fall point is used.  For depth, we see the edge level, the channel bottom, and underside of the plate all chosen in different classical examples.  Horizontally, setting this lower point by the edge, channel bottom, or channel width are all logical.  Classical examples stick within these examples.  

 

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8 minutes ago, David Beard said:

So, take that simple version and add some detail:

1) The radii observed from the channel bottom aren't just random.  Like with ever other f'ng detail, the old Cremona work places and sizes everthing by proportional relationship between parts.  So the radii for these curves are proportioned from the rib height.  

2)  The test for the fall depends the points you choose to test between.  The top point for testing is chosen at or a little ways out from the center line.  The low point choice varies.  Always a logical fall point is used.  For depth, we see the edge level, the channel bottom, and underside of the plate all chosen in different classical examples.  Horizontally, setting this lower point by the edge, channel bottom, or channel width are all logical.  Classical examples stick within these examples.  

 

Are these things which cannot be easily observed with oblique lighting, and a bit of a skill-set?

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Mr. Beard,  I haven't been following all this run-fall evolution, but one question, if you don't mind.  

"The test for the fall depends the points you choose to test between.  The top point for testing is chosen at or a little ways out from the center line.  The low point choice varies.  Always a logical fall point is used.  For depth, we see the edge level, the channel bottom, and underside of the plate all chosen in different classical examples.  Horizontally, setting this lower point by the edge, channel bottom, or channel width are all logical.  Classical examples stick within these examples. "

I haven't sketched all these out.  But wouldn't the above range of choices pretty much cover the range of classical examples using cycloids, circles, and everything else?  Is it just that each instrument is consistent in the way the run-fall rule uses certain end points?  

As Mr. Burgess observes: "Are these things which cannot be easily observed with oblique lighting, and a bit of a skill-set?"  

While using the run-fall rule improved my arches, I'm now questioning whether this much analysis is used and am seeking a rapid workshop rule that gives the "right" looking result.  

Please do not think I am dinging your approach - it is highly educational and imposes a great consistency, but Mr. Burgess seems, at least from my distant perspective, to have a valid observation that making an arch "look right" may well lead to an arch that satisfies the rule.  

I am really enjoying this debate.  Thank you all.  I have two plates ready for final arching, so this is a particularly relevant debate!

 

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David, devil's advocate here to ask if you have run your scheme against a wide sample of various non-Cremonese violins to see if you may have just simply discovered one common type of the violin arch rather than the Cremonese arch? What would you say is different about your plan that makes it specifically Cremonese and excludes other schools?

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Just now, Michael Darnton said:

David, devil's advocate here to ask if you have run your scheme against non-Cremonese violins to see if you may have just simply discovered the violin arch rather than the Cremonese arch? 

Already doesn't work with Guadagnini and Stainer.

They maintain the channel ideas, but fall in differeng rates.

Also doesn't work with some earlier Amati work were the central arching is circle based instead of '1/2 fall in 2/3 run'.

Beyond that, I haven't taken a lot of effort looking at later copy work.  Obviously, you can see lots of stuff has out of pattern bulbous arching, and lots other stuff messes up the channel work.

One they other, I would guess that some copyists have copied well enough to get the arching right by observing well rather than by understanding.

 

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20 minutes ago, David Beard said:

Already doesn't work with Guadagnini and Stainer.

They maintain the channel ideas, but fall in differeng rates.

Also doesn't work with some earlier Amati work were the central arching is circle based instead of '1/2 fall in 2/3 run'.

Beyond that, I haven't taken a lot of effort looking at later copy work.  Obviously, you can see lots of stuff has out of pattern bulbous arching, and lots other stuff messes up the channel work.

One they other, I would guess that some copyists have copied well enough to get the arching right by observing well rather than by understanding.

 

Stainer works if you bend the rule to 1/2 fall in 3/4 run. See the 1679 and 1668.

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Good to hear.  I haven't studied that.  But it feels much more consistent with everything else seen the Stainer simply uses a variant not seen in Cremona than that a maker in a very parallel tradition would just ignore a principle.

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On 10/22/2020 at 1:12 PM, Michael Darnton said:

I guess this would be a more useful discussion if people would state their intent regarding the arching they use. Things like "replicate X", "achieve X tonal result", "make something I personally find attractive, without reference to something else". . . . something like that. It seems like the two of you (Peter and Dennis) are basically discussing personal preferences (choice #3 above) rather than specific objectives, right? That's a point of confusion I've seen throughout this discussion.

My objective is to make something that looks like a Cremonese arch.  But with little experience I'm not sure what that means other than pics of those instruments that have so far been posted.  I made arch templates from the Titian poster but the back plate is turning out to look more like that Amati.   

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