Relocating capstans

[RobertD429@aol.com]

>Our school has a Steinway B from the 1980's  which has terrible
>downweight/upweight problems. The keys in the bass are full of leads, and
>we are still getting downweight between 65-70 grams in that section with
>barely any upweight at all, improving to 60 grams in the treble with
>marginal upweight.

>Upon examining things, we discovered that the capstan on note #1 is hitting
>the heel of the capstan almost at the front of the heel instead of in the
>middle, tapering to almost normal on note #88. We tried changing out
>wippens with several different styles from our kit, but the one which
>worked the best was the original teflon wippen.

This sounds like a description of TWO problems.
  1)A large difference between downweight and upweight means friction,
period. A tight shank flange center makes the most difference, but a
systematic examination of the other friction points might turn up a little
here, a little there. Check the repetition support flange center, of course,
but also check for tight front and center bushings or friction at the knuckle
or capstan. Check the balance rail hole to make sure a tight fit is not
impeding movement of the key.  If the knuckle is large (probably is on these)
there can be excessive sliding friction at the knuckle as it does more
sliding and less rolling due to the angle between it and the top of the
repetition lever. Check the cushion felts on the bottom of the repetition for
dishing. Although the action spread is usually quite consistent on Steinways,
it is still worth a check.
  2) Although reducing friction would certainly bring the downweight down and
raise the upweight, the "lots of lead" part may indicate that this is a
leverage problem, but not necessarily at the capstan line. These parts are
low leverage. Although Steinway says the distance between the shank pin and
the knuckle core is the same as on the older pianos, I have seen some that
were a half millimeter shorter. This coupled with hammers that were heavier
than the hammers of old, means a lot of counterbalancing, which translates
into more inertia, and an action which becomes more resistant to rapid
playing.
Can you take any weight off the hammers?

I don't know why the stack is back relative to the capstan line. At least
nowadays the factory fits the stack to the strike line, then the capstan line
to the stack (causing the capstan line to be variable but the contact to the
repetition to be tidy).  I think I saw a suggestion to move the stack
forward. This would improve the contact between the capstan and the heel, but
would also reduce the leverage between the keystick and the repetition by
moving the pin of the repetition support flange closer to the capstan. It
would cause the hammers to be rehung, lengthening that lever (shank). Check
the ratio between the front and back of the key. You may indeed want to move
the capstans, but it is most likely in order to help out a stack, the
leverage of which is pushed to its limits and maybe a little beyond.

The next time the hammers are replaced, you might experiment with a shank
that has its knuckle farther from the pin, and just increase the dip. I
hesitate to recommend any parts, as things are always changing, but I think
Pacific used to sell a shank with the knuckle distance greater than the old
parts or the current Renner USAs,  but just under the new factory or Hamburg
length. It's better to replace the repetitions at the same time, but if cost
is an issue (ha ha) some shanks will improve things enough leverage-wise that
even if the jack doesn't make exactly a 90-degree angle, it's worth it, as
long as the jack has enough room in the window to go back a little.

Hook 'em Horns
Bob Davis
B. Mus.  UT '68