[CAUT] grand knuckles

[Jim Busby]

Fred,

This is how I've done it for years too. (stretching) Works well with very little time wasted.

Jim

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Fred Sturm
Sent: Thursday, September 24, 2009 8:01 PM
To: caut at ptg.org
Subject: Re: [CAUT] grand knuckles

On Sep 24, 2009, at 11:51 AM, Dan Rembold wrote:

> List,
> I have a Steinway D in our main recital hall that I service, that  
> gets a lot of use.  This piano was rebuilt by another shop about two  
> years ago, and the hammers are holding up well, but the knuckles are  
> already becoming flat and misshapen.  The hammers, shanks, and  
> flanges are Steinway.  It's already to the point that the player can  
> "feel" the jack drag off the front "node" of the knuckle, and  
> getting an exact clean let-off point is hard to do.
>
> I've thought of trying to fluff the knuckles with a brass brush.   
> Are there some other tips that I could use to extend the knuckle  
> life expentancy until the next hammer change?  Flange centers are  
> still good.

	I was never real good at bolstering. Glue between leather and felt  
made placement of the material a problem, and generally it was time  
consuming and the results not worth the effort. That's my experience,  
and others obviously are happy with their bolstering techniques.
	Maybe 15 years ago Ed Hilbert wrote about a different technique,  
cutting one side of the leather away from the shank, stretching it,  
and re-gluing. I tried it, liked it, and that has been my technique of  
choice ever since, for loose leather. I wrote about it in some detail  
fairly recently on this list, I think within the last year. If you are  
interested and can't find it in the archives, I can probably find the  
posts in my sent mail.
	But that is for loose leather. Most of the time, standard treatment  
is brushing with a brass brush (I use refills for a tool designed for  
cleaning barbeque grills, as it is larger and cheaper than a suede  
brush, and essentially the same brass wires - covers more ground  
faster) to remove any build up of any sort, whether dirt or transfer  
of graphite from rep and jack. Essentially restoring the surface to  
being clean and unglazed. Then apply powdered teflon powder. I do that  
any time an action is getting somewhat major procedures done, like  
filing hammers, scuffing tails, and the like.
	I think this treatment is probably the best available for longevity.  
The leather, and the felt under it, are both going to compress over  
time. If they stay clean and lubed, and if the leather is still tight,  
the feel will be okay, in my experience.
	An unbrushed set of knuckles will glaze and the letoff will feel  
draggy after a year of less of fairly heavy use.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu