Now that the back story is out of the way, I have so far cut all the tubing to match my CC and spent hours re-tapering ends of each branch so they fit into the ferrules without gaps.
I have been saving all the replaced parts from the CC for use on this tuba. There has been a debate for decades as to what *exactly* differs between the BBb and CC 186 and I wanted to find out for certain by turning a BBb into a CC and seeing what did and did not work in the process. Any parts on the CC that were not going to be easy to copy for the BBb and that were sort of beat up I replaced with new, and the BBb inherited the old ones after I cleaned them up to a nearly new condition.
By doing this bit of scavenging and then cutting all the bugle branches, valve circuit runners, and inner/outer slide tube sets to the correct lengths I saved a ton of money while the CC got a major facelift.
What I have right now is an assembled set of five rotors with the 1st, 2nd, and 3rd slide circuits installed. I have the top bow installed to the three inner branches, with the 5th branch "pretzel" to the main tuning slide (MTS) chopped to more closely resemble the CC part, which at first glance looks to be the same, but the BBb 5th branch is NOT USABLE on a CC. [
I *think* that if I had to use a CC 5th branch to save an old BBb it could be made to work, but the reverse is not at all possible.]
I have filled about 30 holes in the bottom bow, but the metal is so embrittled that the final reshaping of the bow opened up something on the order of 25 more holes and cracks, so I have a long way to go yet on that part.
All the branch re-tapering went well, though some of it was physically very difficult to do without splitting the tube. Everything fits really well, now. The bell garland I installed looks perfect on one side but needs additional work on the other, so that will have to happen at some point.
The big thing that brought this dormant project back to the fore is that I decided to give the 5th branch narrowing and reshaping a try. I nailed it, too. I am quite pleased with myself. I'm about to enjoy a cheat on my diabetic diet in celebration.
The 5th branch of the BBb has a more natural and graceful curve as it has more space in which to live. The CC part is just tightly wound to fit in the smaller space. I chopped out about a half-inch from the middle of the branch and then made a ferrule. I measured very carefully to find a spot where the taper was less pronounced, the tube was as straight as possible, and that would allow a tube from my junk boxes to fit snugly without gaps. It happened to be just east of the brace beneath that part of the branch so that when the material was removed and the joint was soldered together it was nearly centered on the brace feet. I wanted to use brass so that you would not notice this cut so easily, but all I had was nickel silver, so now it sticks out like the proverbial sore thumb. Oh, well…
This is still very oddly shaped and will set the valve section off from where it goes by about three millimeters. However, the water key elbow from the CC that I scavenged for this horn was installed on the CC when that area was damaged; it was altered in both length and shape to fit that space. If you try to use it in a "corrected" space it no longer fits. This is why it came off the CC and was replaced with a new part. I was sure I could make it work on this horn, but, well: nope. That ain't happ'nin' baby. No way. It is now 3/8" too short to seat into the MTS outer tube correctly. Luckily, the water key elbow is a LOT less expensive than the 5th branch. One is like $15 and the other is like $70. So I get to fudge on this build to the less expensive side, thankfully.
Here are some pics of some of the BBb parts. I did a lot of cleanup today, too, as I had not removed flux that last time I was putting around with the valve section. Tonight the top bow, inner branches, and valve section look much better, and the chopped up 5th branch is clearly visible in the photos.
Here's the obligatory PornPorn…
This is the CC MTS. It will serve as my model today.
First mockup of the 5th branch to see whether my two cuts were in the ballpark…
The CC section has most of the information I need to alter the part using a little "Dremel Persuasion".
This is a press-fit mockup to set the height/angle of the crook end of the 5th branch. The BBb part is a bit flatter/less steep than the CC version. This setup mimics the CC part very well in most regards. Of course, now the water key elbow is too short. It comes too long on both ends and you have to cut it to fit, so this won't be an issue.
Another view of the cut branch and how it lines up on the brace through pure happenstance…
The assembly on the left used to be the BBb 186 pictured in the first post of this thread. Now it is a CC with some new parts and stuff from three other 186 tubas The assembly on the right is the factory CC 186. The one on the left is about six months older than the one on the right. Cool…
This is a better view of how this altered part fits within the frame of all the other altered parts. Every tube in this assembly has been shortened to raise the pitch of the tuba to play "200¢ sharp"…
Another view of the ferruled 5th branch. It is not fully cleaned up. This was the first pass to better allow my failing eyes to see what it up at every joint on the horn. It is easier for me to do this and then study the photos to really clean stuff up.
