Cutting a trombone from Bb to C

[Jimtrombone]

Hello all

I am toying with the idea of cutting a small bore trombone down from Bb to C. Part of this is a certain curiosity about "C" trombones, and part of it is to gain beginner skills in music tech. I have a donor King 606 student horn. I may put a Bb or G valve on it, depending on how it goes.

Has anyone done this? Thoughts or recommendations appreciated.

Jim

[hyperbolica]

A couple guys have done it. A guy named Pete Edwards did it with a bass, and made the Bb valve normally on.
https://trombonechat.com/viewtopic.php? ... ass#p64649

Plus, Yamaha has a small bore YSL-350C with the valve. There are some other odd ones, but that will get you started.

[Jimtrombone]

Thank you, I will have a look at the other thread.

[elmsandr]

Without looking at whatever I may have written in the other thread, you’re going to want to cut from ~111” Bb down to ~99” C. The slide only needs 20.5” of straight extension to get 7 C positions compared to 23” for a Bb trombone.

Good luck,
Andy

[imsevimse]

There were trombones made in C back in the 1920ies. Conn had a model in C called "The Preacher" (Conn 60h). I guess other brands also made C trombones in the past. It would be interesting to know about that. I have never heard about others except the Conn 60h. These trombones are quite rare and do not turn up very often on eBuy. I have one in silver and one in brass. They both has a whole tone valve that you can turn to put it in Bb. Bore is only 0.458. They are rather useless. I have thought of using one instead of an alto in a symphony orchestra but it has not happened. I have thought of getting one of the new Yamaha C trombones. I believe that to be a much better horn.

The model number 60 was reused later for the well regarded single valved Conn 60h bass.

/Tom

[brassmedic]

You need to take off 12 inches. How about cutting each slide tube by 3 inches, take 3 inches off the bell tail, and take 3 inches off the neckpipe. Expand the neckpipe a bit so it fits snug at the tuning slide tube. The bell side tuning slide receiver won't fit over the larger diameter of the cut down bell tail, but maybe if you take off the ferrule it might fit inside the diameter of the bell tail. Then you could cut a slit in the ferrule to bend it open a bit and solder it on around that joint.

Or, if you don't mind having a shorter tuning slide, you could cut down those tubes and you wouldn't have to take as much off of the neckpipe and bell.

Of course if you want to get fancy and preserve the bell/slide position relationship, you would have to change where the bell brace attaches to the bell, and that would make the other calculations more complicated.

[hyperbolica]

If you make it TIS you could elimate more of the tuning slide. That might simplify changes to the bell taper.

[elmsandr]

You need to take off 12 inches. How about cutting each slide tube by 3 inches, take 3 inches off the bell tail, and take 3 inches off the neckpipe. Expand the neckpipe a bit so it fits snug at the tuning slide tube. The bell side tuning slide receiver won't fit over the larger diameter of the cut down bell tail, but maybe if you take off the ferrule it might fit inside the diameter of the bell tail. Then you could cut a slit in the ferrule to bend it open a bit and solder it on around that joint.

Or, if you don't mind having a shorter tuning slide, you could cut down those tubes and you wouldn't have to take as much off of the neckpipe and bell.

Of course if you want to get fancy and preserve the bell/slide position relationship, you would have to change where the bell brace attaches to the bell, and that would make the other calculations more complicated.

On that bell/slide relationship... don’t forget that there is a variable part with the difference required for pitch and a fixed portion of the distance between the end of the slide, the brace and your finger to hit the bell. That is the distance between the end of the slide tubes and the flare that you see and feel doesn’t shrink by the 12th root of 2 for each half step.

(I’ve tried to do that before and made some mistakes in my calculation). Not hard, but measure twice and cut twice. Tis usually easier to make tubes shorter on a second pass than to make them longer after missing the target; aka why I now have an ancient peashooter flare as part of my shop towel holder instead of a playable horn.

Cheers,
Andy