I am evaluating relocation of the capstan line on my Boston grand because the wippen heel cushion/capstan contact point lies well below the "magic line" between the wippen center pin and the key bottom at the center rail pin. At full key depression, the contact point comes just up to the magic line. I made a little adjustable capstan that I can slide back and forth along the key to search for the "sweet spot", as defined by Bob Hohf in his recent PTG Journal articles as the capstan location where downweight is least and upweight is greatest. Moving the capstan toward the center rail key pin will increase action efficiency (Why does there seem to be no trade-off? Am I missing something?). Lets say I move it 10 mm toward the center rail pin (I know, that's alot - just an example), up and downweight is more favorable and the contact point crossed the magic line at half its travel - Perfect! But, I could, for the sake of arguement, install a taller wippen heel, lower the capstan, and move it even further toward the center rail pin, thus increasing action efficiency even more while keeping the heel/capstan contact point right on the magic line at half key depression. What limits me from doing this? Key thickness? (I hope there is something else!) Common sense (or what I perceive to be) certainly suggests that I leave good enough alone, but I want, er a, need, to understand the what and why. What? Why? Anyone? ?-) Terry Farrell Piano Tuning & Service Tampa, Florida mfarrel2@tampabay.rr.com
This PTG archive page provided courtesy of Moy Piano Service, LLC