>Ron, I hope you don't mind if I weigh in on this. I use a 1000g weight >applied to the end of the key (naturals). If the weight bends the key - >measured with a dial indicator - more than 1mm I consider it to be a >problem, ideally is should be under 0.75mm. The key is removed from the >key frame and placed on a work bench. The key is supported under the >balance rail hole and under the capstan. A clamp is place to hold the key >down near the capstan. The weight dangles from a cord off the playing end >with an indicator close by it. The weight is slowly lowered and a reading >is taken. Average several reading to find the key flex. > >I derived the 1mm using data in Pfeiffer's book "The Piano Hammer". Using >the force applied to the key during load play I came up with a figure that >would bend the key 10mm. This along with personal experience led to my >rule - no more flex than 1mm at 1000g. > >John Hartman RPT John, I realized after I posted and left the house that I should have included you in the ask. Sorry about that - an oversight by a poorly maintained used brain. Thanks for the info. Ron N
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