capstan replacement on Bohemia 185

[Farrell]

Capstan friction isn't a big deal if you don't have any, or if it is acceptably low. On a properly set up action you won't have much is any friction loss there anyway because the capstan/heel interface will be on the magic line at half blow.

On a poorly set up action - likely like the one you describe - one can reduce friction a lot by polishing an otherwise rough capstan. If the interface is not on the magic line, that capstan will be doing quite a bit of traveling along the wip heel during key movement.

So the bottom line is that on a well set up action, capstan friction likely isn't a big deal. But on a poorly set up action it can be very big deal indeed. Polishing is great, but it would be best to correct the action geometry also.

Terry Farrell
  ----- Original Message ----- 
  I've heard it said that capstan friction isn't a big deal because the amount of sideways motion of the capstan against the wippen heal is minimal.  I found it interesting, then, that on a new Bohemia 185 I felt some roughness when playing, and was able to isolate it to the capstan/wippen heel interface.  The surface of the capstans was sort of rough, and in some instances had pronounced burrs, as well as overly defined (IMHO) edges.  As a temporary fix, I teflonned the heels.

  Bohemia (now owned by Bechstein, btw, for better or worse) said that they'd go with my recommendation to replace the capstans and re-regulate the blow distance.  The new capstans--of a completely different, polished texture-- arrived a couple of weeks ago.  I completed the agreed-upon task tonight, and when I got the action back in the piano, the difference was absolutely astonishing.  The action felt entirely different, far faster and more controllable.  Both the owner and I were quite surprised and pleased at the difference.

  Now who was it that said that capstan friction is no big to deal?  I beg to differ!

  Thanks for reading,

  Dave
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