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Offbeats Regular Member
Joined: 28 Feb 2005 Posts: 62
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Posted: Thu May 27, 2021 3:43 am Post subject: Question about strange Kanstul backbore |
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Hi folks. I have received some Kanstul backbores (a 10 and a 24) to trial. However on receiving them, the metal on the end of the 24 shank is very ‘“thick” compared to the 10 - which therefore means the exit hole is smaller on the 24. But it’s my understanding that the 24 is a larger backbore, so why would this be?
Does anybody have a Kanstul 24 (or other Kanstul backbore) that is similar or can share some thoughts? The engraving/stamping of the backbore number is quite rough, so I want to make sure I haven’t received a factory mistake or something like that. I’ve attached some pictures - any thoughts from anyone would be appreciated!
Thanks in advance! _________________ Bb: YTR9335CHSII, YTR8310ZS
C: YTR9445CHSII
Eb/D: YTR9636
Picc: YTR6810S
Cornet: YCR8335S
Flugel: YFH631G
Mouthpieces: Undecided |
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Irving Heavyweight Member
Joined: 11 Feb 2003 Posts: 1886
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Posted: Thu May 27, 2021 5:49 am Post subject: |
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You can get a rough idea which BB is bigger by sticking a pencil in the back bore and seeing how far it goes in. Do the same on both. The bigger BB will swallow more of the pencil. Maybe the 24 BB is bigger near the cup but smaller at the end of the shank? It should be easy to tell which one blows more open by playing them. Could also be a stamping mistake. |
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deleted_user_687c31b New Member
Joined: 03 Apr 1996 Posts: 0
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Posted: Thu May 27, 2021 9:42 am Post subject: Re: Question about strange Kanstul backbore |
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Offbeats wrote: | it’s my understanding that the 24 is a larger backbore, so why would this be? |
Are you sure? When it comes to throat sizes, a bigger number means a smaller throat diameter...maybe that also applies to these backbores? (Not saying you're incorrect, I'm just guessing) |
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Tpt_Guy Heavyweight Member
Joined: 16 Jul 2004 Posts: 1101 Location: Sacramento, Ca
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Posted: Thu May 27, 2021 2:53 pm Post subject: Re: Question about strange Kanstul backbore |
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hibidogrulez wrote: | Offbeats wrote: | it’s my understanding that the 24 is a larger backbore, so why would this be? |
Are you sure? When it comes to throat sizes, a bigger number means a smaller throat diameter...maybe that also applies to these backbores? (Not saying you're incorrect, I'm just guessing) |
Backbore bumbers correspond to different shapes, not sizes. Each manufacturer uses their own shapes and numbering system. They do not follow the sizing pattern for reamers and drill bits. When Kanstul copied backbores, they used the numbers designated by the original manufacturers. Usually, letters were associated. I have a copy if a Giardinelli 4 marked "GIR4." This was to prevent confusion between, say, a Bach 3 and a Giardinelli 3, for example.
A Bach 24 is larger in some areas and smaller in others when compared to a Bach 10.
As far as the two shown, are we sure both were made by Kanstul? _________________ -Tom Hall-
"A good teacher protects his pupils from his own influence."
-Bruce Lee |
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Halflip Heavyweight Member
Joined: 09 Jan 2003 Posts: 1906 Location: WI
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Posted: Thu May 27, 2021 3:19 pm Post subject: Re: Question about strange Kanstul backbore |
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Tpt_Guy wrote: | Backbore numbers correspond to different shapes, not sizes. Each manufacturer uses their own shapes and numbering system. . . . When Kanstul copied backbores, they used the numbers designated by the original manufacturers. . . . A Bach 24 is larger in some areas and smaller in others when compared to a Bach 10. |
These are important points. If the Kanstul backbore designations are following Bach conventions in this case, the 24 backbore is intended to give a "bigger, darker, symphonic tone". From what I have seen of drawings explaining backbore differences, this means that the backbore is more 'football-shaped' -- that is, the walls of the backbore are more concave. By comparison, a "tight" backbore designed to favor high-note playing in a big band setting will have a shape that is pinched toward the center (convex walls).
This means that you can't necessarily judge the design of a backbore just by the diameter at the end of the shank. |
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JayKosta Heavyweight Member
Joined: 24 Dec 2018 Posts: 3298 Location: Endwell NY USA
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Posted: Fri May 28, 2021 5:58 am Post subject: |
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The wall thickness of the pictured 24 backbore does look overly thick - is there a 'wire edge' on the ID that hasn't been removed? And the end looks like it has not received its 'final finish' - it appears too rough.
It would require special machining to produce a 'football' shaped backbore. Using a typical bore reamer demands that the finished bore never gets smaller as it progresses from the throat to the end of the shank. _________________ Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'. |
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Halflip Heavyweight Member
Joined: 09 Jan 2003 Posts: 1906 Location: WI
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Posted: Fri May 28, 2021 6:50 am Post subject: |
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JayKosta wrote: | It would require special machining to produce a 'football' shaped backbore. Using a typical bore reamer demands that the finished bore never gets smaller as it progresses from the throat to the end of the shank. |
Forgive my imprecise language -- I should have said "half a football".
I believe my main point that you can't necessarily judge the design of a backbore just by the diameter at the end of the shank still holds. |
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Bogey Factory Regular Member
Joined: 09 Jan 2019 Posts: 56 Location: Springfield, MO
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Posted: Fri May 28, 2021 7:23 am Post subject: Re: Question about strange Kanstul backbore |
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As far as the two shown, are we sure both were made by Kanstul?[/quote]
I'm skeptical about these being Kanstul backbores as well. The Kanstul backbores I've had all have the size engraved rather than stamped. Of course I haven't seen all Kanstul made backbores, just an observation about the ones I've seen. _________________ Justin Shaw |
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JeffM729 Veteran Member
Joined: 27 Dec 2004 Posts: 442 Location: Parrish, FL
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Posted: Fri May 28, 2021 8:19 am Post subject: Re: Question about strange Kanstul backbore |
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Bogey Factory wrote: | As far as the two shown, are we sure both were made by Kanstul? |
I'm skeptical about these being Kanstul backbores as well. The Kanstul backbores I've had all have the size engraved rather than stamped. Of course I haven't seen all Kanstul made backbores, just an observation about the ones I've seen.[/quote]
And most Kanstul Bach backbores I've seen have been labeled B10 and B24. |
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Halflip Heavyweight Member
Joined: 09 Jan 2003 Posts: 1906 Location: WI
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Posted: Fri May 28, 2021 10:40 am Post subject: |
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It occurred to me that I have some trumpet shanks that I purchased directly from Kanstul to try with a custom scanned and altered top that Jim New made for me (at the time, Jim New was still at Kanstul, and Kanstul was still in business). Among them are a Bach 10 and 24.
On both of these, there is no "B" prefix, and the numbers are oriented like the stamping on the "10" shank displayed by the OP -- you have to turn the shank sideways to read the number. (That right there is a 'red flag' -- would Kanstul be so inconsistent that they would orient some numbers parallel to the shank and others perpendicular?)
The edge on the end of my 24 is less than half as wide and flat as the one displayed by the OP, and that, along with the fact that the number is oriented 90 degrees from the way Kanstul did it on mine, suggests to me that the OP's 24 may not be an authentic Kanstul.
The OP's 10 has a correctly oriented number and shank-end edge machining that closely matches my 10, but the number looks very crude compared to mine. Possibly the OP's 10 is also a knock-off, but from a different source.
If you want, I can post pictures of my 10 and 24. |
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