Key Bushing Clearance/Friction, was: Key mortise correction

[David Ilvedson]

OK...I'll bite...won't the protech grease attract dust/dirt...and wear out the bushing faster?   I guess you haven't noticed problem?   

David Ilvedson, RPT
Pacifica, CA 94044





Original message
From: "Roger Jolly" 
To: "Pianotech List" 
Received: 8/12/2006 6:40:17 PM
Subject: Re: Key Bushing Clearance/Friction, was: Key mortise correction


Hi Terry,
                Ric is right' it is touchy, feely kind of thing if using key easing pliers.   How ever I use accurate brass cauls mounted in a 40watt soldering iron. For American made pianos .147" for the balance rail, and .150 for the front rail.
Japanese pianos. .135" BR and .137" for the front rail.  Available from Pianotech.
Do not let the iron get too hot.  The tool will lay the nap of the felt down very nicely.
A thin coat of Protech grease  wiped on to the pins will make the bushing friction come down to the 1-2gm range.

My order for prepping a keybed.

1.  Check and adjust BR hole height.  Make sure you remove all swarf from the key mortice.
2. Polish all BR and FR pins with Flitz metal polish.
3. Apply thin coat of Protech grease to pins. Lubricates and protects against Oxidization.
4. Iron all bushings to obtain above tolerences.
5. Ease OR swell balance rain holes for correct fit.  (If there is any hint of 'chucking' take a damp cloth and hot iron to swell the BR hole.

If you want star performance regulation, then the keybed needs special fastidious attention.

Regards Roger





--- Farrell <mfarrel2 at tampabay.rr.com> wrote:

> Two questions: How do you go about measuring key
> bushing clearance? And how much key friction does
> these specs commonly yield?
> 
> Terry Farrell
>   ----- Original Message ----- 
>   SNIP
>   4. Tight key bushing's.  Gently squeeze the
> bushing to have .002" clearance at BR bushings and
> .005" for FR bushing's.
> 
>   Regards Roger 


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