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So…I have jumped into my F tuba 5th valve relocation project. I am moving my 5th valve on my Big Mouth Brass F. It is currently built into the 4th valve circuit which gives it stuffiness and lots of resistance when the 5th is used. I am going to move it after the 4th valve like most modern piston F’s that are currently out. I have ordered tubing, hoping it will be here in a few days. I will close the gap in the 4th tubing where #5 was. It will require some 90 degree tube bending(a first for me.) I have to cut the knuckle on one side of the rotor to give me a straight entry. Then I have to rebuild the tuning slide to contain the rotor. Hoping I still have enough slide to play with for tuning. I think the tubing for the 5th will fit in the space between it and the plumbers’s loop curly Q. The only part of this I cannot envision a solution to is the new linkage to the new 5th valve location. I need some suggestions from those wiser than me on what style linkage to use. Suggestions would be appreciated. It seems the arm will run on the bell side of the valves down to the rotor with the connection to the thumb spatula between the thumb and pivot point with the mounting point on the first valve tubing or the valve casing. Ideally, I would like to buy parts rather than make them myself. But in this line of work I realize that’s sometimes not possible. Pics below.

https://photos.app.goo.gl/DD88tmfcGfkQaiSk7

Neat. That will solve pretty much everyone’s biggest problem with the BMB lineup.

It sure doesn’t look like there is much room for that tuning slide to begin with. They probably boxed themselves into a corner so they HAD to use the dependent valves. I can’t imagine that was Dick’s first choice when he envisioned these tubas.

I can’t wait to see where you take this!

I believe I have found that the linkage for a Wessex Viverna tuba will be the right configuration for my project. I have contacted them to order it. We shall see.

Update on project. Been busy lately so I haven't had a lot of time to put into this. Removed rotor from 4th circuit tubing and put in a temporary tube to fill in the space. Learning on a steep curve how to fill and bend tubing on a budget. Had to move and reroute some of the 4th tubing to make room for the new place for the rotor. Got a rough-in for the new set up for rotor after valve set into tuning slide. Next step is to figure out how to make the tuning slide usable and how to route 5th tubing out of rotor behind the valves. Still waiting on rotor linkage assembly parts from Wessex.

Photos https://photos.app.goo.gl/XWMoawoDoDtF8XdCA

What did you use to fill the tube for bending? Where did you find it? How much? Inquiring minds...

I used O’Malley bending matrix. You can get it in powder form and blend with water to desired thickness. Then freeze it.

Havent heard of that one. Will check it out. Thanks.

Got notification that my linkage parts from Wessex should be here Monday!

Getting closer! Got everything soldered in place. Did a play test and the result is a success. The 5th valve is now independent and plays significantly more open than before when it was tied into the 4th valve. I’m very excited to see the end product in sight. Pardon my sloppy solder work, I have some clean up, polishing and light buffing to do. My linkage should be in tomorrow and I will begin fitting it to the horn.

https://photos.app.goo.gl/XWMoawoDoDtF8XdCA