Posted by Rick Denney on March 09, 2003 at 12:39:21:
In Reply to: Re: Upgrading S-linkage on rotary tuba posted by Sam Gnagey on March 09, 2003 at 09:28:05:
The ball-joints are made by Du-Bro and thread onto 4-40 threaded rod. That threaded rod will feed through a 1/8" brass tube. That becomes the linkage. The ball joints attach at the ends with brass balls that mount with small bolts to the stop arm (after removing the S-link pin) and the finger-button lever, in the manner Sam describes.
Depending on the instrument, you may need to carefully bend the linkage to avoid interference. I've even carved a bit of the ball joint away where it touched the stop-arm at full travel. A bit of willingness to experiment is a requirement, so buy some extra materials.
Rick "who has done this on half a dozen tubas" Denney