Key pins and key bushings

[Roger Jolly]

Hi Stan,
         I use .002" oversized caul for the balance rail, and .005"
oversize for the front rail. This seems to give the most consistent
results, with little or no squeezing required.  The extra clearence is
needed at the front rail for a couple of reasons, 1. the great amount of
arc that the key is traveling thro', 2. the larger surface area that the FR
pin come's into contact with the bushing cloth.3. A small change in
humidity makes a heck of difference at the front, a bass wood or sugar pine
key swells up significantly greater than the maple key button. 
Hope this sheds some light.
Regards Roger



At 11:58 AM 5/27/99 -0500, you wrote:
>>In simpler words: You can turn key pins with no ill effect if done so
>>thoughtfully and carefully.
>>
>>                Newton
>
>Yes, I agree Newton.  Occasionally we rebush keys for which the pins
>measure 0.144.  Our cauls are sized for 0.146 pins and tend to leave the
>other with slightly more play than we prefer.  In this case, I have no
>concerns with turning the front pins slightly.
>
>It is less acceptable (though certainly not damaging in any way) to turn
>the pins in order to take up side play resulting from worn bushings.  The
>'nested' bushing cloth will contact a greater area of the pin resulting in
>greater friction.  Also the bushing may be worn through to the glue layer
>which obviously increases the friction as well.
>
>Regards,
>
>Stan Kroeker
>Registered Piano Technician
>
>www.pianoexperts.mb.ca
>
>
>
Roger Jolly
Balwin Yamaha Piano Centres.
Saskatoon/Regina.
Canada.