Hi Stéphane Thanks for your reply. Have to think about it for a bit... bore length dependent eh ? I've always taken for given that the bore length is equal to the distance from the strings (at strike point) to the key bed minus the distance of the hammer shank center to the key bed. That puts the shank at horizontal at impact. Raking to make perpendicular to the string with the shank at horizontal at impact would require the hammer to be raked inwards yes ? Which means increasing the actual bore length by the sin of the angle of the rake times the length of the aforementioned formula and adjusting the length of the shank center to middle of hammer molding accordingly. I see no way at all that an outwards rake is compatible with that formula for bore length at the same time being compatible with a requirement of hammer to string angle being perpendicular. The bore length formula could be easily enough modified to work given an inwards rake. That would be (D1 - D2) * cos sin A where D1 is the distance of the string to key bed, D2 is the distance between hammer shank center and key bed and A is the angle between the key bed and the string plane. Bore at that distance would require the center of the molding to be moved out on the shank by a length equivalent to Sin A times the resultant bore length in order to maintain the shank at horizontal at impact while the hammer is perpendicular to the string. Either way... somethings gotta give.. either hammer shank center to center molding, hammer rake, or shank in horizontal at impact. Strikes me off hand that shank being horizontal at impact is a desirable, so if hammer rake is then to be decided by string angle then floating the distance between hammer center and center molding seems to be the only solution. yes ?? RicB Hi Ric. Strings angle up to the bridge from the striking point so anbackwards rake would just make the angle between hammer and string atimpact even farther away from this stated optimal. < Ar, depends on the bore length, not ? Do you use the dummy spare hammers with known bore length trick to accurate the bore length measure ? It shortcuts all measurements failures and approximations, including the less than optimal keyboard frame bedding and the said strings angle up (or down). I can't remember who brought up this trick, but it is one of my top 5 tricks ever learned on this list. Stéphane Collin
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