[CAUT] Re: Moving capstans

[David C. Stanwood]

Alan,

If you want to calculate a target BW to make say a 5.8 R the calculation 
would be:

BW=SWxR+WBW-FW

I took your figures and plugged in 5.8 for R and 9.0 for WBW (assuming that 
it would drop a gram by moving the capstan/heel further out on the 
wippen.   The results are:

     Note   SW     FW    Bwtarget

       1   12.0   41.0     38
       2   11.6   41.6     35
       9   11.2   40.7     33
      10   11.2   37.4     37
      16   11.3   37.0     38
      17   11.4   37.2     38
      28   10.1   25.6     42
      29   10.4   30.5     39
      40    9.8   25.0     41
      41    9.7   26.9     38
      52    8.9   24.2     36
      53    8.6   24.3     35
      64    8.2   15.6     41
      65    8.0   18.1     37
      76    7.2    1.9     49
      77    7.3    1.5     50
      87    5.4   -5.2     46
      88    5.5   -8.6     49


So you could float the capstan boat for any of these samples and find a 
position that makes the BW match the target and that will indicate the 
position for a 5.8 ratio.  If you can regulate dip/blow for that position 
then go for it!

Another approach (calculation free) would be to set the dip to a maximum 
say 10.5mm/.413" and find the position farthest out on the wippen that 
allows for minimum after touch with a short blow.  This would give you the 
capstan position for the lowest regulatable Strike Weight Ratio.

Once you find the new position you can assess the ratio level and determine 
if you need to alter hammer weight accordingly.  If the result of a few 
samples comes out to say 6.0 or higher then your going to have to lighten 
the hammers to 1/2 medium or lower unless you can improve the geometry to 
yield a more efficient action.   If it's a Chickering expect the unexpected!

It is my observation that the most efficient actions have the highest 
distance to weight ratio.
In other words the actions that multiply distance (and speed) the most and 
with the lowest weight ratio by proportion are the best.

I don't have a set up for measuring movement of the hammer vs key but as I 
have said checking the dip/blow result gives the answer we need.

David Stanwood