[TPIN] Bell Bow (NOT Bilbo Baggins!) Bends

[Bob Osmun]

Ben, I have no idea what you are inferring about cryogenic restoration.

The point I was making before is that thinner wall bells found on LT180 
trumpets and the Chicago model C trumpets hold their cross section shape 
better with ice as the filler for bending the bow than do  medium-heavy 
bells. It is much harder to maintain the critical dimensions in the bow with 
ice when the brass has a thicker wall

The solids that are used to support tubing for bending a bell bow include 
lead, pitch and frozen soapy water. There are different advantages to using 
each. Lead at room temperature will support the cross section of tubing 
better than nearly anything else, but  makes it harder to bend a tight 
radius. Pitch is more sensitive to changes in room temperature.  If too cold 
the pitch will shatter and if too warm the pitch will not provide adequate 
support, both will cause the tube to collapse. Also cleaning out pitch is 
VERY messy, involving melting the pitch and burning it out or dissolving the 
remainder with harmful chlorinated solvents . Frozen soapy solution or ice 
can provide the necessary support and cleans up easily. Just hang up the 
bell after bending and the solution melts out cleanly when it warms up to 
room temperature. However, it does not always support  the brass tube as 
well as pitch or lead.

Correction of elliptical bell bow cross section is something we've been 
offering for years. It is part of  a "blue printing" process that can 
include measuring and correcting MPC receiver gap, precision valve alignment 
and inspecting for concentricity of tubing and removal of solder blobs. I 
doubt very much that Vincent Bach ever intended these irregularities to be 
included in his original designs. FWIW when a bell bow that is pinched is 
corrected, the sound of the trumpet really open up. To quote local Boston 
freelance trumpet player Dana Russian " That's the best $50.00 I've ever 
spent [repairing] on my trumpet!"

My 2 cents.

Jim Becker
Brass Repair Specialist
Osmun Music Inc.
www.osmun.com


----- Original Message ----- 
From: "Ben Rydell" <benny at benrydell.com>
To: "Bob Osmun" <rosmun at osmun.com>
Cc: "MATTHEW STOCK" <matthewstock at sbcglobal.net>; "Michael Anderson" 
<manderson at okcu.edu>; "Jon" <jon at yakatus.com>; "TPIN" <tpin at tpin.okcu.edu>
Sent: Tuesday, March 11, 2008 11:55 AM
Subject: Re: [TPIN] Bell Bow (NOT Bilbo Baggins!) Bends


> Apparently cryogenic restoration means nothing to a Bach that has a 
> properly assembled
> bell bow bend, when all the vibrations are accounted for.
> Insights?
>
>
> Bob Osmun wrote:
>> I feel it is important  to point out my observation of the bell bows on 
>> the Bach Chicago model C trumpets.
>
----- Original Message ----- 
From: "Ben Rydell" <benny at benrydell.com>
To: "Bob Osmun" <rosmun at osmun.com>
Cc: "MATTHEW STOCK" <matthewstock at sbcglobal.net>; "Michael Anderson" 
<manderson at okcu.edu>; "Jon" <jon at yakatus.com>; "TPIN" <tpin at tpin.okcu.edu>
Sent: Tuesday, March 11, 2008 11:55 AM
Subject: Re: [TPIN] Bell Bow (NOT Bilbo Baggins!) Bends


> Apparently cryogenic restoration means nothing to a Bach that has a 
> properly assembled
> bell bow bend, when all the vibrations are accounted for.
> Insights?
>
>
> Bob Osmun wrote:
>> I feel it is important  to point out my observation of the bell bows on 
>> the Bach Chicago model C trumpets.
>