Regulating Woes

[Terry Beckingham]

Hi Newton,

I have done the checks that you suggested. The main action rail appears to
be straight as an arrow. I wonder if the butt springs have too much tension.
When disengaged they are slightly above the top of the hammer butt, which I
believe is about right. I hesitate to reduce the tension lest I end up with
bobbling hammers.

There are very few weighted keys, only from F6 up to C88. 

I don't really know what the touch weight was like before I worked on this
piano as pretty well everything was shot. Everything was very loose and
sloppy. I did lots of re-bushing and re-pinning along the way. I have been
doing this type of work just for the experience in hopes of someday passing
the technical exam. It's a slow grind with the nearest RPT being 400 miles away.

I have only the supply house gram weights with the nut, so my measurements
may not be too accurate. Here is what I came up with:

Note     DW    UP   BW    FR
C1       53    36   46    8.5
F1       56    36   44    10
C2       48    33   40.5  7.5
F2       54    33   43.5  10.5
C3       54    33   43.5  10.5
F3       56    33   44.5  11.5
C4       52    32   42    10
F4       54    32   43    11
C5       56    33   44.5  11.5
F5       54    35   44.5  9.5
C6       54    35   44.5  9.5
F6       58    42   50     8
C7       58    40   49     9
F7       60    42   51     9

I have had very little to do with weight measurements, so I don't really
know what to look for. I can see that the balance weights are too high and
friction is too low in some areas.

I'll have to dig out my reprint book on Hammers and Touchweight and do some
reading.

Thanks for your interest.

Terry
(Wishing I was on the way to KC)

At 02:32 PM 7/19/99 -0400, you wrote:
>Changing the location of the capstan, which you did by moving them
>back, will change the touch weight.
>
>Like you I am uncertain why this has occurred but I would check and
>see that the main action rail in not warped either when the action is
>in the piano and when it is not.  I did have this problem in a grand
>action once.
>
>An easy way to check this when the action is in the piano is to
>stretch a thread along the edge of the wippens below where is wires
>enter and see if it is bowed outward.
>
>If everything checks out then you may consider removing the lead
>weights from the backs of the keys.
>
>Determining optimum touch weight for an upright is not so easy because
>of the hammer springs.  Any variation in their tension will effect
>touch weight.  With that said:
>
>What you are most interested in is not the actual touch weight but the
>average of the up and down weights and half the difference.  The
>average is the balance weight and half the difference is the
>friction.  Like so:
>
>Make sure all hammer springs are properly engaged and in perfect in
>performance.
>
>Touch weight is always taken without dampers involved to block down
>the sustain pedal.  
>
>Touch weight is defined as the maximum weight a key will lift from
>just before before jack involvement and minimum weight required to
>depress a key to just before jack involvement all the while jogging
>the action to release pin stiction or excess friction.
>
>Down weight is 61 grams and up weight is 15 grams.
>	(61+15)/2=38   this is actually an excellent balance weight
>	(61-15)/2=23   this is excessive friction so go look for it and fix
>it.
>	THE BALANCE WEIGHT WILL NOT CHANGE even when the friction does.
>
>BUT you want 36 grams of balance weight so:
>
>Subtract 7 grams (half the friction) from the down weight then place a
>small key weight on the key and slide it back and forth until the key
>goes down while thumping on the keys.  Mark the location of the
>weight, drill a hole in the key and press the weight into place.
>
>New balance weight. Friction should be in the 8 to 15 gram range.  Up
>and down weights will vary according to the amount of friction but the
>average should be made to be the same you decided you want.  Balance
>weight should be at 35 grams for an extreme low and 40 as an extreme
>high.
>
>Don't try to deal with 1/2 grams.  Round down to an even number for
>subtracting from down and adding to down weight.
>
>Take a few measurements and post them so we can discuss them.  Measure
>all Cs and all F#s.
>
>Lots and lots of fun, especially without a full set of graduated
>weights.
>
>By the way, if you are using supply house stacked weights with a nut
>on top you will need to calibrate those weights.  The smaller weights
>van be as much as 30% too heavy.  You will need a fine balance or
>digital scale to do this work.
>
>		Newton
>
>