[pianotech] key bushing problem

[David Nereson]

    I rebushed a set of keys using the nylon Spurlock cauls. 
The pins were .146" so I used that size caul.  When done, the 
keys still wobbled laterally (balance rail).  This has happened 
a couple times now.  I had done no easing or ironing after 
removing the cauls.  Should I have used a smaller caul (even 
tho' the size I used is meant for that size pin) or thicker 
bushing cloth?  Or both?  When I initially determined what 
thickness cloth to use, by laying the trial cloth across the 
mortise and pushing a key pin into the hole, thick seemed way 
too tight.  Medium was just right (could be pushed in, but 
holding the key upside down, the pin would not fall out -- this 
is according to the Spurlock directions).
    Once I steamed 'em all back out and rebushed with thicker 
cloth, but using the same cauls, and they still came out too 
loose (too much lateral play).  So do you use a smaller caul 
than the one intended for a given size pin?
    --David Nereson, RPT