TromboneChat

Hi all,

I just received a new rotor plate from Conn-Selmer for a King 607 bell I've had for a while. Naively, I'd assumed it'd come with witness marks and would fit my valve casing without modification. Not so: both the outside diameter and inside diameters are roughly 1mm oversize, and there are no witness marks. Is it usual to have to file/mill/lathe the surfaces and scribe one's own witness marks?

I could probably sandwich the rotor plate between rubber washers and _carefully_ chuck it into my drill, but beyond that, a tech's time would be far more economical than purchasing a lathe or mill.

It would be nearly impossible to re-machine it perfectly concentrically and flat to the center hole. Possible, but not likely. I'd try again to get a correct one.

Doug Elliott wrote: ↑Thu Jan 20, 2022 9:33 pm It would be nearly impossible to re-machine it perfectly concentrically and flat to the center hole. Possible, but not likely. I'd try again to get a correct one.

This ☝

Machining it correctly the first time, easy. Indicating it back to zero and modifying on something that narrow requires some kind of fixture, and a lot of patience.

Thanks, gentlemen. I'll do exactly that. I enjoy an interesting project - but only if it has a chance of succeeding!