TromboneChat

I can't find the thread, but awhile ago a few of us were wondering what the difference between these two parts is, but IIRC, nobody actually had any experience with the parts.

https://instrumentinnovations.com/copy- ... -628-bore/
https://instrumentinnovations.com/solde ... -605-bore/

Thinking that maybe the .605 was a small bore version of the threads... I went ahead and ordered one because I have a project I'm planning on using one that I can go either way for. Turns out, the .605 has "large bore" threads, meaning it accepts Shires and Edwards (probably other) .525, .547, and .562 pipes. I tested all of them on mine and it works fine. Presumably, this means that the .628 also accepts the same pipes and the difference is the size of the cork barrel it is being soldered to.

If you are curious what I could do with either size, I recently had a King 3B (508) slide converted to accept threads (shoutout to Brad Close who did magnificent work on it). I already had a "large bore" set of threads on hand, so I just sent them to him and it worked fine. His shop has threads for Kanstul/Shires 525, 547, and 562 slides on hand, so I just had him add that ring to the top and it worked great for the 32H copper replica I had made. The horn this will be going on has a 500 upper slide.

The "bore" on these parts refers to the outside diameter of the mouthpiece receiver on the trombone. I have installed several of these, mostly on Bach instruments. Since there is great variation in the outside diameter of the mouthpiece receivers (even among the same models), I usually measure the specific horn with a micrometer and order a specific custom size to the 1/1000th of an inch from Mike Olsen at Instruments Innovations. It takes a few more days, but the fit is always perfect. It is also what Mike recommends should be done because he knows that the manufacturers are not consistent.