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Expanding bottom bow joint

PostPosted: Wed Jun 26, 2019 9:13 pm
by roweenie
A question for the pros:

Is there a method that one can use to expand the large end of a bottom bow to accept a slightly larger bell tail and ferrule?

The difference in diameters is about an eighth to three sixteenths of an inch, maybe too much?

Re: Expanding bottom bow joint

PostPosted: Wed Jun 26, 2019 10:43 pm
by bloke
If you can laminate some hard rock maple together, have a wood lathe + skills, and have a Ferree's dent machine. Otherwise, I wouldn't attempt it.

Re: Expanding bottom bow joint

PostPosted: Sat Jun 29, 2019 8:09 am
by roweenie
Thanks bloke - on to plan "B" :tuba:

Re: Expanding bottom bow joint

PostPosted: Sat Jun 29, 2019 11:02 am
by KiltieTuba
What about making a "long" ferrule with a spacer in the middle? Some of the King tubas have this.

Re: Expanding bottom bow joint

PostPosted: Sun Jun 30, 2019 6:36 pm
by roweenie
That's an intriguing idea, KT, but I don't have the facilities to make a ferrule that size.

It would be really cool if there were some sort of "data bank" of the measurements of different available bells - maybe there's one already in production that would "fill the bill" of what I'm looking for........?

Re: Expanding bottom bow joint

PostPosted: Mon Jul 01, 2019 3:33 pm
by bloke
roweenie wrote:That's an intriguing idea, KT, but I don't have the facilities to make a ferrule that size.


Yes you do...You would just cut a section out of some tuba bell that is the proper length (and cut from the proper portion of the bell) to fit your bell (large end) and to fit that bottom bow (small end)...the ACTUAL issue - not that you don't have the facilities - being that it would look like $h!t. :|

Re: Expanding bottom bow joint

PostPosted: Mon Jul 01, 2019 11:26 pm
by Dan Schultz
I have one of those small open-ended rolling mills. I think I could cut a long ferrule from an old bell stem that's rather thick and expand one end by thinning the material on that end. I've made ferrules larger this way but not attempted to make just one end bigger. I'll fiddle with it when I get some of the current stuff off my bench.

Re: Expanding bottom bow joint

PostPosted: Tue Jul 02, 2019 7:28 am
by Ken Herrick
It isn't that hard! Visualise things a bit. Something needs to be smaller and the other needs to be bigger.

Required tools - a torch and something like a Dremel.
I won't go too far now as I have been thinking and drinking but will give more detail here or by PM or email if you want more info.