Hammer Weight vrs Friction

[Jon Page]

These figures are from a S&S B.
This, of course is just one scenario, your mileage may vary.

Touch Weight dropped by 10gr with the removal of 1.2gr SW

The Friction difference is negligable because a judgement call
was made while surveying and in the second line, 24 UW or
59 DW could have been decided on, there is a degree of
fudge-factor. So the difference is not considered significant.

#	UW	DW	SW	FW	KR	BW	F		SR
16 	34 	68 	11.9 	32.8 	0.53 	51 	17.0 		6.33 
16 	25 	58 	10.7 	32.8 	0.53 	41.5 	16.5 		6.15 

To make the DW decrease, one or more of the following:
- more weight removed from the hammer
- more weight added to the front of the key
- ease friction (DW decreases, UW increases)
- change leverage

On this piano:
- SW is in the lower quarter of the 'med. range',
  not a whole lot can be further removed.
- key is already loaded with lead, no more room
- the friction is fine for this note (F will not change BW)
- the KR is good (although uneven) and the action regulates well

My advise from this point was to install wippens with assist springs.
That way, lead could be removed from the front of the key and the
spring would compensate thus creating a 'lower mass' action.
At that time I would target a BW of 38; I like an UW over 20gr for
repetition purposes, so since F =16      38BW - 16F = 22UW.
The notes below C16 will have a F a few gr. higher so this will
keep those UW's up as well.
The SR will drop again with the assistance of the spring.

The customer is considering this further refinement and in the
mean time is enjoying a lighter touch and may decide to keep 
things as they are. 

Just another 'rebuild' salavation, tomorrow a M&H rebuilt
'truck-like action' to make controllable.

Keep 'em comin'



Jon Page
Harwich Port, Cape Cod, Mass. (jpage@capecod.net)
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