Key Leads and Inertia

[Ron Nossaman]

>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