[CAUT] Which S&S replacement action parts?

[Fred Sturm]

On Jun 25, 2008, at 9:18 PM, David Ilvedson wrote:

> I have been working at this very thing at Stanford.  Repinning all  
> the D's.  I repinned the Hamburg to 4 grams and a year later it was  
> maybe 1 gram.   I repinned again and used the very same center pin  
> but had the friction back up...I was able to get about 5 grams.   I  
> think the bushing cloth is polishing the center pin and lowering the  
> friction.   My question is how do you know if you have adequate  
> firmness?   At least I can measure the friction level accurately...
	Yes, there's the rub. OTOH, friction per se isn't a very useful  
measurement, if it is going to change and be unreliable.
	Take key bushings. A wee bit of ironing on firm cloth with raised  
hairs, and you can reduce the friction by a great deal (as measured in  
UW/DW), and the key itself feels the same (in wobble/lack thereof).  
Spongy cloth can have very high friction, and have a great deal of  
side play at the same time. I think action centers can easily be the  
same.
	My own process at this point, when I repin a full set of shanks, is  
to try not to remove any felt. I go up a pin size (half size, .001")  
using burnishing to get there. Fast action with the burnisher,  
creating heat. And apply protek to every bushing. This seems to make  
it possible to get lasting and consistent results. And I feel  
reasonably confident I have the best firmness I can get.
	With Steinway, impregnated bushings, well, I find they stay firm  
quite well over long usage, and that measuring friction doesn't tell  
me a whole lot.
>
>
> I've repinned a bunch of newer Yamaha grands measuring at barely 1  
> gram.   I definitely find a much more focused tone.   Cleaner and  
> eliminating, for a time, voicing issues...

	I agree, with standard felt bushings I have the same experience. I  
believe that if the friction is that low, there will be a fair amount  
of wobble as the hammer is thrown, and that is where the change occurs  
(less wobble, not because the added friction "slows down" the motion).  
OTOH, I have found some of those Asian centers where there is high  
friction, and still there is wobble - noticeable when feeling the end  
of the hammer, knocking. IOW, friction is a dangerous thing to focus  
on in and of itself. That is essentially the point I am trying to  
bring up here. When someone says "I repinned to a precise X grams of  
friction" what does that mean? Could mean a lot of different things  
depending on technique and materials.

Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu