Trombone dimensions for DIY project

[MrDillon]

Hi all,
I recently began a project to create a new trombone valve. However, I do not have much knowledge about instrument design so as far as proper dimensions are concerned I am in the dark. I would like to mount this valve on a Bach 42 so Bach dimensions would be ideal. If anyone could provide any of these in inches it would be a big help! Thanks!
-MrDillon

-Wall thickness and diameter of Bach 42 rotor casing
-Diameter and width of Bach 42 rotor core
-Outer diameter and wall thickness of rotor knuckle
-thickness of rotor from the inside of the core(on stop arm side) to the outside of the casing(on the stop arm side)

Other general questions:
-When designing something to be milled out of brass what is the thinnest any wall should be? (ie. hole in a rotor core that is close to the outside of the core)
-Tolerances between valve core and casing?

[ithinknot]

I do not have much knowledge about instrument design so as far as proper dimensions are concerned I am in the dark.

[reaches for popcorn]

I say this to save you time and grief - if you have to ask any of the above, you have no business attempting this.

Fortunately, the universe already contains plenty of valves, and there are probably people on the forum who would give you a used Bach 42 rotor for the cost of shipping.

[Doug Elliott]

My thoughts exactly