 The Clarinet BBoard
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Author: Dan Shusta
Date: 2005-01-19 19:39
(Mark C., if the following is not appropriate for the BB, please delete.)
I believe the following may be interesting only to those who work on mpc refacing and perhaps others who would like to know a little bit more about using feeler gauges to check mpc facings. WARNING: there is quite a bit of math involved here!
A few weeks ago I saw a Brandt refacing manual for clarinet and saxophone up for bid on an auction site. There seemed to be quite a few people interested in it and the last time I checked the price was around $70. One of the things that caught my eye was the great number of facing charts available in the manual. The manual appeared to be quite old and I began to lament that manuals like this don’t seem to exist today.
As I sat pondering about different facing lengths and tip openings, I began to wonder if somehow I could produce my own set of charts. After reading an article by Santy Runyon in which he thought the best facing curve was simply the arc of a circle, I began to think about coming up with math equations for mpc measuring work. One of the first things that I realized quickly was that the radius of the arc was dependent upon two independent variables: the total facing length and the tip opening. Changing either one of them meant changing the radius of the arc.
Since I had forgotten the basic algebraic expression for a circle, I did a quick search on the internet and I found what I was looking for: that the radius squared equaled the sum of x squared and y squared. (rr = xx + yy). (“rr” means “r” squared because my computer can’t produce the squared symbol.)
Since tip openings and feeler gauges are usually in thousandths of an inch, both of these parameters will need to be changed over into mm and that is done with the following equation:
Eq. #1 T (tip opening in mm) = tip opening in inches/0.03937
Next, I set out to determine the equation for the radius “R”. By doing some basic algebraic work on the formula for a circle, I came up with the following:
Eq. #2 R = (TT + FF)/2T where T = tip opening in mm
F = total facing length in mm
Next, when I realized that a feeler gauge was equivalent to a tip opening with just a shorter facing length, I could then look for a formula to determine “M”, the actual measurement with a feeler gauge because the radius was now a constant.
Eq.#3 M = F – (2GR – GG)1/2
where M = actual measurement with feeler gauge
F = total facing length in mm
R = radius figure from Eq. #2 in mm
G = feeler gauge thickness in mm
(Note: GG means G squared and (xxx)1/2 means the square root of the quantity between the brackets.)
As I began to use Eq. #3, I began to notice that even with a 0.0015” feeler gauge, the equated measurement was quite far removed from the known total facing length. I began to suspect that Eq. #3 was somehow incorrect. However, when I put a feeler gauge thickness of 0.0001” into the equation, the equated measurement was now much closer to the known total facing length. To check the accuracy of Eq. #3 even further, I used a feeler gauge thickness of 0.00001” into the formula and the equated measurement was extremely close to the known or supposed total facing length. Now I know that a 0.00001” feeler gauge is impossible; however, I remember reading a post response by one individual who refaced mpcs with a 0.0001” feeler gauge. (Sorry, I don’t remember who that was.)
So, you might be asking yourself, what is the purpose of all this? First of all, it is possible to use common feeler gauges from 0.0015” on up to do basic measurements on the mpc facing with a properly graduated glass measurement plate available from various music repair specialty stores. All you would need to know is the published facing length in mm and the tip opening in mm or inches. (Both of these could actually be off, but, at least it’s a start in the right direction.) Then, with the use of even a basic calculator, you can determine the measuring points for whatever feeler gauges you have on hand.
What was very surprising to me and which fostered within me a much greater respect for the professional who actually refaces mpcs was the discovery that the 0.0015” feeler gauge (which I remember in another Brandt book as being the smallest feeler gauge that they used) was so far away from the known or supposed total facing length. When I read the post from a fellow who used a 0.0001” feeler gauge, I thought “Why is he using such an incredibly small feeler gauge?” Now, I know! IMO, it is extremely difficult to set the total facing length correctly. Now I know why many posters say to try many mpcs of the same model…because machines are not perfect and the tolerances needed for a proper facing are so extremely tight (and is extremely difficult to measure accurately) that it is very difficult for manufacturers to duplicate them from one mpc to another. (The difference between an 18mm and a 19mm facing is only 0.04” and, IMO, that makes a huge difference is playability!)
So for those who are truly interested, please feel free to use the above formulas to construct your own charts. (For greatest accuracy, carry out the decimals as far as your calculator will go.)
(For a 2 page Word document showing the derivations of the formulas, please send me a blank email with “Formula derivations” as the subject. I will return your email with an attached document which will show the diagram I constructed in determining the equations in a step by step manner.)
Please keep in mind that I am basically a hobbyist and am not a professional at this!
I’m not sure if the above has any value at all, but, it sure was fun! And I learned a lot!
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Author: BobD
Date: 2005-01-19 20:06
I haven't read or studied all of your thesis, but can you tell me if you are assuming that the arc of the mp is a segment of a circle?
Bob Draznik
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Author: Dan Shusta
Date: 2005-01-19 20:22
Exactly.
I took Santy Runyon's opinion that a circle arc makes the best facing.
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Author: Alseg
Date: 2005-01-19 21:06
Santy used the word "circle" loosely, I think.
Actually the arc is more parabolic or ellipsoid, or a compound parabola where one portion (say from the part of the facing that meets the reed to the middle of the rail) is one equation, and another portion (middle of rail to tip, in this example) another equation.
Just a thought, maybe Walt G. or Greg S. or Vytas could elaborate...or maybe a physicist.
Former creator of CUSTOM CLARINET TUNING BARRELS by DR. ALLAN SEGAL
-Where the Sound Matters Most(tm)-
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Author: David Spiegelthal ★2017
Date: 2005-01-19 21:16
I don't believe a good facing curve can be described by any standard curve --- I would guess a polynomial (rather high order) would be the best fit.
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Author: Mark Charette
Date: 2005-01-19 22:48
David Spiegelthal wrote:
> I don't believe a good facing curve can be described by any
> standard curve --- I would guess a polynomial (rather high
> order) would be the best fit.
A NURBS surface would be a proper form for describing the facing since there are some facings with non-symmetrical rails and/or a dip in the facing. you can ev en add a trim curve if you want ... pretty straightforward stuff nowadays if you're an engineer.
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Author: Dan Shusta
Date: 2005-01-19 22:59
To D.S.:
Is this polynomial published anywhere or does each mpc maker have their own secret formula?
Another question: If the formula is secret, how can other mpc refacers successfully achieve the same feeler gauge readings that the manuf intended?
Just one more question...If all of the formulas are different, could this be the reason different makers of a mpc with 18mm facing with a 0.041" tip opening will play differently? (Discounting the interior baffle design)
This is really getting interesting...
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Author: Dan Shusta
Date: 2005-01-19 23:13
Mark C wrote:
"A NURBS surface would be a proper form for describing the facing since there are some facings with non-symmetrical rails and/or a dip in the facing. you can ev en add a trim curve if you want ... pretty straightforward stuff nowadays if you're an engineer."
Where can I learn more about the NURBS surface? Is this standard material in college textbooks? Are there books available on the open market that delve into this kind of material?
All the reading I've done talked about how the rails absolutely had to be perfectly symmetrical. What playing advantage is obtained by non-symmetrical rails?
How can a refacer check the measurements on any mpc and and know if they are correct?
My thanks in advance.
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Author: Mark Charette
Date: 2005-01-19 23:21
Dan wrote:
> Where can I learn more about the NURBS surface? Is this
> standard material in college textbooks?
Pretty much - it stands for a Non-Uniform Rational B-Spline surface (and you trim it using Non-Uniform Rational B-Spline curves). Plenty of math books cover it. It's the surface form of choice for most 3-D design nowadays. Type "nurbs" into google and you'll get about 383,000 hits.
> All the reading I've done talked about how the rails absolutely
> had to be perfectly symmetrical. What playing advantage is
> obtained by non-symmetrical rails?
There are some very well-known makers (such as Jim Pyne) who create asymmetrical curves on purpose, and if you look at some of the real-life measurements you'll find assymetry. Can't tell you what it means in terms of playing, though ...
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Author: Vytas
Date: 2005-01-20 00:25
Dan,
Before you come up with any math equations for mouthpiece measuring work, at least you have to have basic understanding about clarinet mouthpiece facings and design. If you think that all you have to do is just squeeze a circle arc from the beginning of the facing and the tip and you'll get a perfect facing, you're kidding yourself. It doesn't work like this.
Here's one example of the American standard facing for 1.06mm tip opening.
6
12
22
34
Believe me; there is no circle arc in this facing and if it had one, mouthpiece would be unplayable. (in a sense of tone quality and stable sound.)
The facing alone is meaningless. You can not discount "the interior baffle design", because the facing is just a small part of the bigger picture and all these parts must be in perfect balance or a mouthpiece will not play well.
Vytas Krass
Professional clarinet technician
Custom clarinet mouthpiece maker
Former professional clarinet player
Post Edited (2005-01-20 22:56)
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Author: Dan Shusta
Date: 2005-01-20 00:42
Vytas,
Thank you for your response. Did you get those numbers from some published book? Also, are there standardized feeler gauges that go with those 4 numbers?
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Author: Dan Shusta
Date: 2005-01-20 19:38
Hi everyone,
I just reread Santy Runyon's article on the Runyon website and it stated emphatically that Santy believed the best facing curve for the clarinet mpc was indeed a section of a perfect circle and not a combination of various types of circles.
I decided to call Ruyon and talk to them about the article. I asked one of the production workers there if their current production followed Santy's belief that the curve should be a section of a perfect circle and was told: "Oh, yes. We still use a machine that Santy set up in the 50's".
I have read several posts by people on this BB who said that they are very pleased with their Runyon jazz mpcs.
So, with all due respect to the mpc professionals who made comments about the curve needing to be of a higher order math than the arc of a perfect circle, if this were really true, I think Runyon would have gone out of business a long time ago.
Just my opinion...
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Author: Mark Charette
Date: 2005-01-20 20:01
Dan wrote:
> So, with all due respect to the mpc professionals who made
> comments about the curve needing to be of a higher order math
> than the arc of a perfect circle, if this were really true, I
> think Runyon would have gone out of business a long time ago.
Santy Runyon is but one manufacturer; whether ot not what he came up with is perfection is highly debateable. I can read a few hundred posts on "jazz" mouthpieces and come up with near as many suggestions.
Hopefully the setup of the machine has been checked and fixed over time, or it is highly unlikely to be a chord anymore.
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Author: Dan Shusta
Date: 2005-01-20 20:21
Thank you, Mark, for your comments. It caused me to think a little bit about the possibility of changes in their machinery, so...I gave them another call.
I talked to the same production worker and found out: 1) he has been working with this very same machine set up by Santy Runyon for the last 33 years; 2) absolutely no modifications have been made to this machine; and 3) this very same machine is still being used today to turn out all of their "custom" models.
In all fairness, he also mentioned that they have another machine which uses a different curve for the student model.
I never stated that a section of a perfect circle was the perfect facing for a clarinet mpc. I believe I stated that it was Santy Runyon's belief that a section of a perfect circle was the best curve for the clarinet mpc.
Since many types of curves are being used successfully today, it seems obvious (to me at least) that many types of curves are possible and that a section of a perfect circle just happens to be one of them.
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Author: David Spiegelthal ★2017
Date: 2005-01-20 21:20
Other than some sort of mystical belief in the beauty and purity of a perfect circle, there are no scientific or empirical grounds (other than Mr. Runyon's belief) that an arc of a circle is the "optimum" (whatever that is!) facing curve for a mouthpiece. I have tremendous respect for Mr. Runyon and his work, but in all honesty I've been sent as many of his products for refacing as any other maker's. There is no one best mouthpiece design for any instrument or any individual or any playing style. One thing I can guarantee is that my preferred facing curve is nothing like a constant circular arc, it is more like a higher-order spline as described by Mark --- curves fairly sharply at the transition or 'break' from the flat table, then holds a flatter curve for a while, then curves a bit more sharply again near the tip. Usually.
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Author: Dan Shusta
Date: 2005-01-20 21:48
Thank you, David, for your comments. They are much appreciated.
Since I have read many responses from BB members about how they loved their mpcs after being refaced by you, your preferred facing curve is obviously of high caliber and produces results well enjoyed by many.
Would it be safe to say that the higher order math facing curves are simply better than the basic section of a perfect circle?
I think this is so because it appears so many mpc refacers fashion their curves in a much more complex manner than just the arc of a perfect circle.
I also think it would be interesting to find out how the more complex facing curves actually affect playability. Perhaps these are trade secrets and rightly so.
Thank you everyone for your comments.
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Author: Mark Charette
Date: 2005-01-20 22:02
Dan,
I think you're thinking too hard ...
There are an infinite number of possible curves for a facing. Of this infinite number, some subset will be usable for manufacturing and playing. Of this subset, there will be a subset that some set of people will find the usable, and some smaller set will find "just right" ....
In other words, some mouthpieces will work for some people but not for others. Luckily we have a fair number of manufacturers who make a variety, pretty much ensuring that you can find something "just right".
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Author: Dan Shusta
Date: 2005-01-20 22:23
Thanks, Mark, for your enlightening comments.
I think all of this is very good information to know. In the past, all that seemed to be important to me was the total facing length and the tip opening. It never even came into my mind that different manufacturers, for example, would have totally different facing curves for the exact same total facing length and tip opening.
And, I really liked David's following statement:
"There is no one best mouthpiece design for any instrument or any individual or any playing style."
I like to think that his statement is really all encompasing and is very true.
On another note...as for thinking too hard...what else have I got to do? I've been unemployed for over a year and thinking hard is the only way I can maintain my sanity.
You have no idea how much I appreciate this BB!
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Author: Vytas
Date: 2005-01-20 23:51
Dan wrote:
***"Did you get those numbers from some published book?"***
I've never read a book on the subject and really don't care for one. I've learned from the masters themselves and by studding the work of others. This cannot be replaced by a thousand of books. IMO
You have to learn the basics first and please don't start from the other end by creating formulas to construct mouthpiece refacing charts. LOL
Clarc Fobes wrote:
"Curve - most often referred to as "the facing" This is the portion that arcs away from flat and allows the reed to vibrate in interesting ways. It is not actually a full arc to the tip. The area just below the tip is flat. The length of the curve is measured from the tip to the point where the arc breaks away from flat. Always decribed in millimeters".
http://www.woodwind.org/clarinet/Equipment/MBL/Mouthpiece.html
Vytas Krass
Professional clarinet technician
Custom clarinet mouthpiece maker
Former professional clarinet player
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Author: Alseg
Date: 2005-01-21 01:01
Here is one way to record the curve.
This is found somewhere in these pages....but I can not remember where.
oh well....I will send it to Mark and maybe he can attach it.
Former creator of CUSTOM CLARINET TUNING BARRELS by DR. ALLAN SEGAL
-Where the Sound Matters Most(tm)-
Post Edited (2005-01-21 01:04)
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Author: Alseg
Date: 2005-01-21 03:24
Thanks Mark
I forget where I got this...it is not mine, but it was posted for all to see and use.
Former creator of CUSTOM CLARINET TUNING BARRELS by DR. ALLAN SEGAL
-Where the Sound Matters Most(tm)-
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Author: Dan Shusta
Date: 2005-01-21 05:21
Thank you sooooo much, Alseq and Mark. This program is absolutely fabulous!! I never knew such a program even existed!
I think there will be a few others besides myself who are going to bookmark this program for their use.
My only question now is how many different names of arcs can be put in? Or is this for a circular arc only? I certainly hope it can create different kinds of arcs.
I can't thank the both of you enough!
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Author: BobD
Date: 2005-01-21 13:01
Dan...I truly appreciate your quest for scientific information on mpc facing. I do not do mpc facing on a regular basis and do not claim to know anything about it but rather believe that Mark's comments above pretty well state the case. May I suggest you try something that I did and that is take a mp that doesn't play well for you and go about changing the facing yourself until the mp starts yielding a decent response. Then continue and see what happens. This is strictly a learning experiment and not guaranteed to yield a mp that you will treasure.
Bob Draznik
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Author: D Dow
Date: 2005-01-21 22:56
The baffle of a mouthpiece and it's bore exert such a profound influence over the instrument that it would be interesting if someone would chart the differences in tuning and timbre from one type of baffle/bore configuration to another.
David Dow
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