Posted by John Swensen on February 22, 2001 at 12:49:03:
In Reply to: Re: A Rim Question posted by Jay Bertolet on February 22, 2001 at 08:19:10:
Rim (inside) diameter is a funny thing; because of the (more or less) rounded inside edge, there is some question about where to measure the inside diameter. Most manufacturers have some standardized way to measure the inside diameter (for example .063" down from the highest point on the rim for tuba mouthpieces, .031" down for euphonium mouthpieces, .016" down for trumpet mouthpieces, etc.), but there seems to be little consistency among manufacturers. Thus, one manufacturers 1.325" rim might be considered a 1.310" rim by another manufacturer.
Another factor that can confuse the issue is the "feel" of the rim on the embouchure; a more rounded rim may feel (and respond) as if it were bigger than a sharper-edged rim that measures the same. Also, silver tends to be stickier than gold, so it feels smaller, while polycarbonate (Lexan) feels stickier than silver, so it feels (and responds) like a smaller diameter silver or gold rim.
I guess what I am saying is that two rims of different (measured) diameter may feel similar enough to each other to be compatible with each other, and won't mess up a player's embouchure.