Happy and prosperous New 2016 to All :) 
 

 i've been wondering on how would you duplicate  a well playing facing curve 
 that doesn't fit any of the radial or elliptical curves onto a different tip opening ,facing
 length & diff tip rail thickness ?
 How would you calculate - program that in a spread sheet you use for regular curves?
  Or are you guys just eyeballing the source facing curve irregularities you want to implement onto a target facing curve?
 

 Here is an example of a well playing facing curve from a mouthpiece 8* ( 0.115") facing length 25mm, tip rail 0,26 that doesn't completely fit the elliptical ratio 3.5 , 

 it is more curved from the facing start, but fits the elliptical ratio from the middle of the curve with a slight bump near the tip.
  Looks similar to  facing curves i've found on many vintage Otto Links . 
 

 what are your thoughts on that?

 dimitri
 

 

 

If you have detailed curve readings, you just use them to duplicate the curve on another mouthpiece.  No need to create a curve fit.

Theo used to have a section on his site showing that he used a 3rd degree polynomial to fit facing curve data.  He called it "the Ring".  I have a slide of it include in a PowerPoint presentation I did in 2009.  It is under the "Clinic" area of my web site.



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> On Jan 23, 2016, at 11:02 AM, jazzroom@... [MouthpieceWork] <MouthpieceWork@yahoogroups.com> wrote:
> 
> [Attachment(s) from jazzroom@... [MouthpieceWork] included below]
> Happy and prosperous New 2016 to All :) 
> 
> 
> 
> i've been wondering on how would you duplicate  a well playing facing curve 
> 
> that doesn't fit any of the radial or elliptical curves onto a different tip opening ,facing
> 
> length & diff tip rail thickness ?
> 
> How would you calculate - program that in a spread sheet you use for regular curves?
> 
>  Or are you guys just eyeballing the source facing curve irregularities you want to implement onto a target facing curve?
> 
> 
> 
> Here is an example of a well playing facing curve from a mouthpiece 8* ( 0.115") facing length 25mm, tip rail 0,26 that doesn't completely fit the elliptical ratio 3.5 , 
> 
> it is more curved from the facing start, but fits the elliptical ratio from the middle of the curve with a slight bump near the tip.
> 
>  Looks similar to  facing curves i've found on many vintage Otto Links . 
> 
> 
> 
> what are your thoughts on that?
> 
> dimitri
> 
> 
> 
> 
> 
> 
> 
> 

Thank you for reply Keith,  I do have the readings from a source mouthpiece that is 0.115" / 25mm facing. 
 but if my target mouthpiece should be for example to 0,105" tip 24,5mm facing length and a 0.020 tip rail.
 how do I recreate the source   curve onto new target mouthpiece... without a new numbers plot?
 I am puzzled, sorry if I am missing something here?
 

 How would u call this type of irregular curve a  parabolic , Power Curve, or....?
 

 Dimitri

Well the curve has parabolic features, but it is not pure one.  I have not been impressed with this type of curve on sax so I have not tried to work out a family of curves.

You could fit it with a polynomial then use scaling factors to stretch or compress it in the X and Y direction.

> On Jan 23, 2016, at 8:37 PM, jazzroom@... [MouthpieceWork] <MouthpieceWork@yahoogroups.com> wrote:
> 
> Thank you for reply Keith, 
> 
> I do have the readings from a source mouthpiece that is 0.115" / 25mm facing. 
> but if my target mouthpiece should be for example to 0,105" tip 24,5mm facing length and a 0.020 tip rail.
> how do I recreate the source   curve onto new target mouthpiece... without a new numbers plot?
> I am puzzled, sorry if I am missing something here?
> 
> How would u call this type of irregular curve a  parabolic , Power Curve, or....?
> 
> Dimitri
> 

A three degree polynomial prescription (this is technique used for optics) will give you a better representation than you can reproduce with tooling unless you have an optical quality machine shop.  Note your manufacturing error will be more than any error from the curve unless you have lots of money (millions) tied up in your numerical controlled tools.

Bill Harwood