Jim Also consider this. Long key or short key... the key is like the engine and the action being the transmission device. With the key dip , usually .393/10mm at the key pin, the overall key travel,.... give er take some wiggling, only raises the capstan roughly 5 mm , on any key. Only 5 mm. So key flex a side its not traveling ling very darn much. And that 5 mm of travel distance is mechanically advantaged into approx 60 mm of hammer movement by the action geometry/levers. Fairly amazing. So the question remains about the affect longer keys (meaning longer from the capstan to the check location) may affect back check function. So is all this questioning coming from some recalcitrant actions failure to check? FWIW....Many, including me, appreciate a slightly longer tail. I like to measure 1" from the bottom of the shank to the bottom of tail. This leaves some wiggle room for future hammer wear and plenty of tail to contact the back check. I like the back check and the tail to be at the same elevation at the bottom of the slow test key stroke. I don't think there is any magic here just acceptable parameters. Dale The 72deg check face (how'd you do that degree sign), 2-1/2"-3" rad tail, back check head height 1mm below tail at letoff, 1" min tail...are these specs that work on "standard" 17"-19" length keys only (call it 8-1/2"-9-1/2" back lever)? What about a shorter back lever, with its smaller radius at the backcheck? ALthough "D's" go the other way and have longer key lengths than 17-19, so maybe that shouldn't change things that much?Jim Ialeggio -- Jim Ialeggiojim at grandpianosolutions.com(978) 425-9026Shirley, MA Dale Erwin RPT- Mason & Hamlin/Steinway/U.S pianos Pre-hung Ronsen hammer sets/Abel parts Sitka Soundboards & Supplies WWW.Erwinspiano.com 209-577-8397 -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20120229/801c64c9/attachment.htm>
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