Well, I thought I had answered this in earlier posts, but my plans developed as I was doing several unplanned alterations, so my reasoning may have been rather thinly explained.
So here it is, all in one post.
I had badly needed to relocate my thumb ring since I bought this tuba. I usually remove the thumb ring if this is the case, possibly moving it or making/buying a replacement later. However, this tuba has an odd balance point and is very heavy. (It outweighs my 186 by at least five pounds.) So I quickly decided that I needed a thumb ring but that it would have to be adjustable.
With the thumb ring gone, I did not notice just how badly located the lever platen was. After years of suffering from pain in my thumb while using this tuba, but not at all with my 345 or 186, one day while working on this tuba I was comparing some photos, and one was of me playing this tuba.
And my whole hand was in a really awkward position, and I was playing my 3rd and 4th valves with the THIRD joints on those fingers. To reach the thumb platen my entire palm had to be shoved almost on top of the pistons. I just play. I don't think of stuff like this as I play. If a physical issue causes me pain or makes it difficult to play I will address it. (One of the greatest sets of improvements I ever made to a tuba was to unkink my hand and spine positions for my Yamaha YFB-621, which was truly awful from the factory.)
Once I was aware of the source of my problems with this Kurath, I made some comparison photos that showed the positions of all five fingers on the 186, the 345, and this tuba. I was surprised by how bad it was on this tuba, too. So I started the process of figuring out how to get the same nice, relaxed hand shape that I had on the other two horns, which is nearly identical and very comfortable. This is an interesting realization since one has five vertical rotors and the other has 4+1 pistons set at a 45º angle.
Here is the Holton hand position, rotated to sort of match the Kurath.
Here is the same hand shape pasted onto the Kurath, and you can see how far off the thumb ring and lever were. The lever was the issue, as the ring (a replacement) was adjustable and was in a reasonable location in this photo. The original fat boy ring (not on the horn in this pic) was located even higher and closer to the platen. It was painful, and I could not use the lever unless I shifted my hand almost off the valves or my knuckle would have to be shoved hard up into the ring. This adjustable ring from Jürgen Voigt fixed that one, specific problem and allowed me to at least have a ring — but it was not a real solution.
Here is the tuba as I received it. Try to imagine the Sasquatch-like hands needed to play with this spread and be comfortable. Perhaps, if Andre the Giant played the tuba and he used that silly crab claw hand position that some people actually teach to children… Seriously, details like this need to be fully worked out before a horn hits the market. This man continually modified and tweaked this tuba over many years, the thumb position and the lever being one of the things he changed at least once. (He altered the layout of the 4th slide circuit at least three times for which I can find photographic evidence. Charging customers a premium while expecting them to "guinea pig" your "beta quality" tuba for you is pretty unethical, IMHO. I am surprised that buyers accept this. (And things like the shitty intonation most tubas today seem to have. WTF is up with tuba players?) And yes, I'm talking to you, too, Gerhard Meinl, with your ten different iterations of your model 2165.) Come on, guys — DO BETTER!
Here is a newer version of the Kurath, the original Willson 3200FA-5. Note how Herr Kurath himself recognized this issue and corrected it. His corrected thumb rind location is closer to where I decided to put mine. Note that he is still using a "puller" linkage. AND, importantly for the pain in my thumb, his levers (on my tuba and on this one in the photo) are "rollers" in that they cause the thumb to twist laterally, as the fulcrum is TO THE SIDE of the thumb rather than ahead of it as with normal rotary valves, like Miraphone. This HURTS ME LIKE YOU WOULDN'T BELIEVE! The photo above of my Kurath's lever is my first replacement lever, to set up the initial change to a "pusher" system. The platen is exactly located where it was with Herr Kurath's lever; I just moved the fulcrum from the side 90º to be ahead of the thumb.
Here is where I am now, as a comparison. Look at the difference between this and the photo of the original position.
It is important to note that Herr Kurath's lever is a "puller", with the fulcrum in the center. You push it down and the other end comes up, pulling the valve action toward the lever. I had already decided (and bought, installed, etc.) a 6th valve, and for the new 5th and 6th levers to work well, they both needed to operate in the same direction, and in this setting, they would have to be "pushers" with the fulcrum at one end, the platen and link connecting point either together or very close, on the same side of the lever. This was because of my idiotic idea to retain the 5th lever for the right thumb. If I had been willing to man up and play this as a proper 4+2 tuba all of this could have been avoided, as the 5th lever directly connected to the 5th valve with no lever between them would be very easy to make. Very easy. Very, very freaking easy. Since I am congenitally unable to leave things alone and keep changing plans midstream as I discover what I really want for this tuba, I chose to follow the stupid path I am on.
"Stupid, you say? Oh, come on, Wade. Lighten up!"
Well, all this engineering and design wanking is just that: I am doing this to see if I can do it. BECAUSE I WILL LIKELY REMOVE ALL THIS AND REPLACE IT WITH A SIMPLE CONNECTION BETWEEN THE UPPER 5TH AND THE VALVE ONCE I AM COMFORTABLE PLAYING THE HORN IN THIS MANNER.
I am determined to make this work, despite the stupid angles, arcs, fulcrum locations, lengths, and depths. The reality is that I will probably remove all this within a year. That was my plan all along, and I have the upper-lever-only linkage already made. So when I joke around about chucking the whole thing and do just that, I am actually quite serious.
But I am absolutely committed to making this work, even if it *does* end up in a box to be used for parts on some other project in the future.
And maybe, if it works well, I may just retain the two-handed 5th functionality.
I hope that answers this question for the lurkers in this thread. Thanks for your interest. If I come off as frustrated, it is because I am not used to having to redesign anything more than once. I am very good at this specific type of work, so it is unusual for me to have to go to such lengths to make a "simple lever". And it is unusual for me to have to accept repeatedly that a "simple lever" does not do what I had planned for it to do.
But this set of parameters is a genuine mess.
).
