Keys and MOI - wipp assist

[Don A. Gilmore]

----- Original Message ----- 
[link redacted at request of site owner - Jul 25, 2015]
To: "College and University Technicians" <caut@ptg.org>
Sent: Thursday, January 08, 2004 6:26 PM
Subject: Re: Keys and MOI - wipp assist


> We Piano technicians are used to measuring in grams and centimeters. It
> is, as you said, somewhat awkward to use kilograms and meters instead
> but I think you are right in directing us in this direction.
>
> Some of us have been measuring the MOI of various action parts.
> Naturally we have been using gcs. For grand keys I have been getting
> about 10,000 20,000 gmcm^2. I assume I would divide these by 1,000,000
> to covert to kgm^2? So the new numbers would be .01 to .02 kgm^2. Please
> let me know if this is right.

Actually it would be a factor of 100,000.  There are 1000 grams in a
kilogram, but there are only 100 centimeters in a meter.  I have always
thought that choosing centimeters for the cgs sytem was rather odd.  Most
everything else in the metric system is used in even multiples of 1000, so
the common prefixes are kilo-, mega-, giga-, or milli-, micro-, nano-, etc.
Centi- is a bastard prefix.  Oh well, they dreamt this stuff up in the
Nineteenth Century...go figure.

> Don, you are an invaluable resource for this list.
>
> John

Thanks, John.  You guys know much more about the workings of the piano than
I.  I just try to offer what help I can in a general sense and let you guys
have fun on your own.

Don A. Gilmore
Mechanical Engineer
Kansas City