Mouthpiece Fit and Gap...again.
"As part of my testing process
I monitor every Sonare trumpet for mouthpiece receiver gap.The average depth of
the receiver to venturi on Blackburn-Sonare mouthpipes is very nearly 1.125"
every time with very little deviation. So if your mouthpiece enters your Sonare
trumpet 1" then you will have close to the target .125" gap. I will often see
significant variance from one mouthpiece maker to another based on his or her
mouthpiece design. Schilke and Yamaha mouthpieces have smaller diameter tapers
and will gap much less than most, while some Stork, GR, New Bach and others with
larger diameter shanks will gap more. When I test gap with my Bach large letter
1 1/2C on the Blackburn-Sonare trumpets I will get very near to the .125" target
gap."
I hope this helpful.
_________________
James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
www.osmun.com
Sonare Winds Brass Tester
www.sonarewinds.com
We don’t agree with all Jim’s
classifications of measurements above but we do agree that they are all over the
place. Being a journeyman toolmaker, gauge maker, and machine builder, GR
has developed a method to measure shanks using GD&T (Geometric Dimensioning and
Tolerancing). This takes form, function, and fit as well as establishing datums
into consideration. These special gauges have been made to gauge maker standards
and jig ground for total precision. As Jim mentioned variation even from certain
manufactures can be huge. It can vary from wear, replating, too much plating,
variation in taper and many other reasons.
NOTE: It is NOT possible to accurately measure the end shank dimension with a
caliper or micrometer!
Why? Because it is a taper; any slight variations of measuring from the end of the shank and you have missed the dimension, furthermore, there can be wear on old mouthpieces, damaged end of shank, as well as a slight radius on the end from polishing or it may be machined that way. ( See pics below)
The only true way to measure it is with GR’s method. This is a theoretical dimension. (See below).
Other Manufacturer's Shank
GR Shank
Most older Schilke are at the small dimension, end shank
dimension of .382” We have not seen any of the newer ones.
We don’t agree with the Yamaha measurements from Jim’s findings. That doesn’t
mean Jim is wrong but he probably measured a different era of mouthpiece. We
find the newer ones to be about .386 to .389, and most about .387. The
older ones were much smaller. Stork’s are up around .388 to .390.
GR are .385 for most standard-Not FD’s, there are some made for Najoom and
Haefner at .383. We do make customs and that number is engraved on the MPC.
New Bach’s are .384 to .387 and drifting upward. The older one were .382- .383
and the worn out ones can be as little as .378.
“When I test gap with my Bach large letter 1 1/2C on the Blackburn-Sonare
trumpets I will get very near to the .125" target gap.”
What is the theoretical end shank dimension of the mouthpiece you are using?
We have master plug gauges that are precision ground for this. If you have master gauge @ .383 and set every horn to be a .125 gap then you have a precision measurement using a “Qualified Standard”.
If the gap is .125 with a .383 older Bach mouthpiece what is the gap with other diameters?
.382 = .105
.383 = .125
.384 = .145
.385 = .165
.386 = .185
.387 = .205
.388 = .225
.389 = .245
.390 = .265
On the other hand if the .125 was check with a newer Bach at .385 what would you get? Big difference!
.382 = .065
.383 = .085
.384 = .105
.385 = .125
.386 = .145
.387 = .165
.388 = .185
.389 = .205
.390 = .225
Conclusion
To make life easier and find a correctly gapping mouthpiece “Industry Standards” would only make sense!
If GR and Jim Becker had a trumpet and it came from the factory with a .385-.125, it would be easy to make a mouthpiece shank to the correct gap with that information. Right now you need to be a toolmaker to understand the variations and invest in $$$$ in gauges.
Do you want to keep paying for sleeves, custom shanks, new receivers, receiver adjustments, worrying, driving yourself nuts, and just wondering “what’s the problem” or “is there a problem”? Of course not! Unfortunately that is the case now, and always will be unless the industry agrees to standards and can actually hold tolerances.