Apologies if you misunderstood me and vice versa. I think we both agree about degreasing and the care that goes into handling muriatic acid. I didn't want to suggest that he attempt it without knowing plenty about what he is doing since like you pointed out it is a very dangerous procedure. For example, you mentioned the dilution method and degreasing. Second, I didn't mention lapping to get rid of dirt or oil. I mentioned it to get rid of any uneven grooves that may have formed over time. This wasn't exactly a high recommendation either - just a suggestion if the other methods don't work, which they should. Schmid valves are built to an incredibly high tolerance, yes, but if they are installed improperly or if something gets in there to cause uneven wear (including corrosion) then friction will play a role. Sorry for anything that was unclear - we probably agree on mostly everything even if I wasn't very clear in some of my communication. -William In a message dated 1/31/2011 5:05:32 P.M. Eastern Standard Time, [email protected] writes:
William wrote: "First, someone said that strings being too tight was a mistake on this horn, but I personally don't like any play with the string. Pulling the strings tight seems to not be a problem for me as the valves work fine that way." I wrote this, but you misunderstood me. The lower rotor should be strung as normal (no play in the string), but the upper rotor should have only a slight play in it to allow the completely free rotation of the rotor and full swing of the lever arm. If you tighten the string too tightly, it will bind and will pull the rotor stop armature just enough to pull it out of alignment and to cause it to bind. The natural tendency when turning the string holding screw (the one at the end of the linkage lever) is for the string to tighten. I have seen this on almost every Schmid triple I have worked on. The proper balance of tension and slack is critical on this linkage. And also wrote, "It can also be dirt on the valves. So, I'd involve this procedure:" The OP took this horn to two technicians and I doubt that he or she will be interested in doing this work by himself/herself. The steps mentioned are generally the right idea, but the need to degrease before acid cleaning was left out. Anyone who works with muriatic acid does well to take extreme care, as some brands on the market are extremely concentrated and ought to be diluted before use, handled properly (always pour acid into water and not the other way around), and stored properly. The fumes alone can destroy anything made or iron or steel within the near vicinity over time. (Ask me how I know this, sometime.) But the procedural steps were finished with, "10. If it's still there, take it to a pro who can either lap the valves, clean it more thoroughly, or do something else to make it better." I would almost never recommend lapping these valve rotors. Schmid rotors are just about as good they come when they are cleaned and installed and lubed properly. There should be no need to lap these rotors. Lapping should never be used to take off dirt, oil, and buildup. -- *Regards, Dave Weiner Brass Arts Unlimited* _______________________________________________ post: [email protected] unsubscribe or set options at https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/valkhorn%40aol.com _______________________________________________ post: [email protected] unsubscribe or set options at https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/archive%40jab.org
