[CAUT] moving capstans question

[Keith Roberts]

If you had one of Dale Erwins Action Ratio Kits you could measure the action
ratio without having to worry about friction as a component. Basically it
depresses a key 6mm for you and there is a mm measuring tool to measure the
hammer rise. Then you read the ratio from the side of the tool. I just
replaced the hammers on a 6'2 Grotrian and it had 5 leads in the bass just
like the situation you describe. Grotrian moves the stack to find strike
point and that put the capstans on the the back of the wippen heel, beyond
the red underfelt in the center of the heel. The action ratio measured 1 to
6.3. I determined that moving the capstan to the front of the heel changed
the action ratio to 1 to 4.8. When I put it slightly forward of center, the
ratio was 1 to 5.5. I now have three leads max in the bass. The keys
themselves have a lot of mass so now this piano plays like dream.

On the S&S, Moving the knuckle is the usual case but Steinway does move the
stack on the key frame to find the strike point. Tokiwa is making really
nice parts and has 17 mm knuckle placement shanks and whips that match. In
Dale's shop I just did a Renner back action for a B and then a Tokiwa back
action for somethindg. They were done almost side by side and I had less
traveling and alignment to do with the Tokiwa parts. I was much happier with
the wippens too.

Keith Roberts

On 9/21/07, Paul T Williams <pwilliams4 at unlnotes.unl.edu> wrote:
>
>
> Hi List!
>
> Happy Friday!
>
> I am working on a 70's Sty B with a horrible action geometry problem. All
> the students and the professor hate playing it and I don't blame them! The
> line from key balance hole to wip has the capstan way too low making the DW
> close to 70g throughout.  It has a renner action and hammers.  the wips and
> capstans are such that I could relocate the capstans back by about 3-4mm.
>  Would that make a big enough difference in the DW? It won't affect the
> line.  I looked at raising the stack, but there isn't enough room to raise
> it more than 1-2mm.  Should I try both?
>
> Also, is the measurement in Steinways made from center of balance rail
> hole on the top of the key, or from the back of the key?  This is a new
> endeavor for me and I don't want to make things worse.
>
> Still green in Lincoln,
>
> Paul
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