Key Bushing

[Kenneth Sloane]

To All- At Oberlin we shim key mortises as necessary with materials of
appropriate thickness. We like to have the mortise at a dimension that will
allow bushing with a very dense flange bushing felt. Two sizes seem to work
for all our Steinways  -- one with a nominal thickness of approximately
050-.055" and the other .060-.065". We measure the felt with a mitutoyo,
spring-loaded, dial-gauge micrometer.

For shimming the mortise we use hard paper stock if only a small shim is
necessary and the kind of veneer that comes in rolls -- like adhesive tape
-- for larger shims. We glue these in with titebond and clamp with the metal
spring clamps that are made for key bushing but should never be used for key
bushing (they force all the moisture from the glue into the felt).

We determine what shims and felt sizes to use by doing samples on the
keyboard. Sometimes we will shim on only one side.

Ken Sloane, Oberlin Conservatory
===============================
--On Fri, May 26, 2000 11:54 AM -0600 "Jeff Stickney" <jpage@selway.umt.edu>
wrote: 

> Dear List:
> 	I just got done unbushing the keys from the Steinway D which is over-used
> in our recital hall.  The bushings came out in about 25 minutes since the
> last set was bushed using hot hide glue, but the dilema is this:  The last
> time they were bushed I used quite thick cloth - .062 or better and it was
> barely thick enough for many keys.  I am thinking of going to leather for
> longer wear, but would like input on what to do for the enlarged mortises.
> Should I be shimming them with veneer (using waterproof Titebond II?) to
> get back to a .050 thickness of cloth/leather, or just try to find a thick
> enough leather to end up with a tight bushing?  I can imagine a thicker
> material might also cause problems on the shoulder of the front rail
> mortises - it could be trimmed flush but that adds one more step.  Is it
> time to consider new keys - and what kind of expense would that incure?
> Thanks for your ideas.
> Jeff Stickney, RPT
> University of Montana
> jpage@selway.umt.edu
>