Bell re-spinning?

[sirisobhakya]

I have always wanted a gold brass bell flare for my Yamaha YBL-835D. But Yamaha won't sell the flare separately; the only way to have a gold brass flare is to buy an entire bell set. But with the price tag of 68,000 THB (approx. 2,200 USD), it is far beyond my capability.

I then talk to a local tech (considered one of the best in Thailand), and they say they can provide a bell flare, cut from a pre-made bell, first on a trial basis at around 250 USD. So I accepted.

The problem is that Yamaha's bell taper and ring position is quite unusual, and the new flare is almost 2 cm shorter than the original bell. Intonation-wise it is acceptable (my horn is quite flat with the current mouthpiece combination) but the position of the bell throws my slide position off almost entirely. Yes, I understand that a good trombonist should be able to play with ears and without using visual reference, but I am not that good obviously... The tech offers to make an extension ring, but I am not quite comfortable with that given the flare is already much heavier than the original flare.

Is it possible to spin a bell, with its rim already rolled but not soldered, ti increase its length? If possible, what tools are required? Or should I abandon my hope entirely?

[tbonesullivan]

Spinning a bell requires a big lathe, a mandrel, and specialized equipment to apply pressure to the bell as it is spun. However I don't think you would be able to make the flare longer easily without also making it much wider. I don't know of any way to make the stem portion of the bell longer.

Now, I do recall that Burgerbob / Aidan has installed Bach bells on some Yamaha bass trombones. That might be an option if you really want to have a different alloy bell. What are you trying to achieve by swapping out the bell aside from just having something you perceive as better than what you do have? Did you notice a large difference when you had the Gold Brass tuning slide for your YBL-830?

[Burgerbob]

Most of what makes a bell sound the way it does is the taper. I'd say second is the weight, and finally the material.

It sounds like you have a totally different taper bell in a totally different weight, so the material difference is going to be pretty negligable.

The Bach bells I have put on yamahas were the exact same length, so had no bell position issue. What was this new bell from?

[sirisobhakya]

Thank you for your responses! I have to clarify: I would like only the bell flare to be made, not swapping the entire bell. My objectives are:

- Mainly to study whether the tech can make a spare/replacement bell flare in case the original one is damaged (I have dropped it once already, luckily it was from a shallow height so the damage was minimal), and options I can order.

- To try new weight, alloy, and construction. I understand that the sound might not be that different, but if I can have spare bell flares with different configurations to try at 250-300 USD each, I am not complaining.

The (short) flare was made from a Chinese-made OEM bell. The construction looks OK, but it is quite heavy. And as it turns out, the taper is different enough to cause the position problem.

[Burgerbob]

Ahh, you're talking about the flare after the screw. That makes much more sense. If they're using a Chinese mandrel from something with a narrower throat than a Bach 50 (I would assume the 7B copy mandrel), then the same point on the screw ring will be much farther along the length of the bell (making the flare short).

If your tech can source one of the 613H copy flares, that should be pretty much an exact match- although heavier as well, at least in original form.

[timothy42b]

Hmm.
Does anyone make a carbon fiber bell flare, past the screw? It might be easier to experiment that way.

[RobL]

Hmm.
Does anyone make a carbon fiber bell flare, past the screw? It might be easier to experiment that way.

https://butlertrombones.com/custom-trom ... fications/