Inre a thread about which new hammers for an older Steinway, we digressed onto action parts, i.e.
ED may be talking a lighter version for a 13mm knuckle placement,, eh?
The following is a digression of a digression, but there is so much emphasis placed on keeping a brand all genuine that the impropriety of the modern parts is often overlooked.
A 1912 Steinway B. The original knuckles were 15.5 mm from the pin. The bottom key has two leads in it. The leading is erratic, but minimal. The DW,( with SW's following the boundary of Stanwood's chart 'tween light and medium) progressed from 51 in the lowest octave, losing about a gram per octave as I went up. I didn't compute BW's, as a full WNG is going in. The piano has had a professional life, and is destined to continue as such.
What I have arrived at is the 16 mm knuckle placement. The Ronsen Weikert hammers can be made light enough to allow this geometry, and, in fact, it was a better fit in the piano's architecture. That fit encompassed custom boring the hammers for squareness to string and shank at contact, which often requires shorter boring in the top octaves, and longer boring through the middle. 1 7/8" blow leaves the lowest shanks 2 mm off the rests, and .390" dip allows .035" aftertouch without jamming the jacks.
The WNG aspects of Steinway action replacement allow things others cannot. This piano had the heavy capstans. 7.5 grams each. Replacing with the low-friction aluminum parts takes 3 grams off the key while effectively removing friction from "magic line" considerations, (another tangent which I will leave alone, for now). This is a "free" 3 grams off the DW, which costs neither geometry or lead. If I want, that change allows another ,6 grams to be left on the hammer. In this case, it meant that I could forego the 16.5 knuckle that would otherwise be needed to keep the lead down. I wanted to keep the ratio high, like the original, but took a small compromise. The WNG system lets me set the knuckle exactly where I want it, and they are all the same to within thousandths. Can't find that consistently anywhere else.
I think there is a difference in physical response between various actions of identical DW but differing hammer weight/action ratio, or differing hammer weight/FW. The original action in this piano, in order to provide a medium touch, would need ultra-light hammers. I have changed that by .5 mm at the knuckle and 6 grams reduction in capstan weight, leaving me with room to hang hammers from light to med-light.
I have seen pianists respond well to a high ratio, low SW action. The shorter knuckle distance makes a lot of velocity available, and with the Ronsen hammers, I can still get a lot of fundamental in the tone without a lot of weight Factory replacements would require a 17 mm knuckle and over .400" dip. I am seeking a different feel, and one that I think is closer to the instrument's original than what new stock parts would provide.