[CAUT] S&S Key Bushings

[Fred Sturm]

On Oct 31, 2008, at 5:48 AM, Mark Dierauf wrote:

> Fred -
>
> While you have your pipe cleaner and teflon powder out, hit the BR  
> holes as well. I follow that up with the balance hole easing tool  
> inserted from the bottom side without any more pressure than the  
> weight of the tool itself...just a couple of turns to burnish in the  
> teflon powder. It definitely seems to free up slightly sluggish BR  
> holes without removing or crushing any wood.
>
> - Mark Dierauf
	
	I prefer McLube (applied with pipe cleaner) for the balance holes on  
the theory that it will stay put better. The powdered teflon adheres  
well to felt, and rubs in well on keybeds, but I'm a little skeptical  
about balance holes, though I guess your suggestion about burnishing  
with the easing tool might overcome my skepticism.
	The balance hole wood often gets coated in who knows what (sticky  
black residue) in an older piano. In that case, I think it is a good  
idea to ream very lightly, either just running a precise sized drill  
bit through it (hand held, just a push pull motion) or using a precise  
reamer of a size not over .001" above the pin size. Reamer used very  
conservatively, just a 90 degree back and forth motion or so. That  
will clean out the crud and size everything consistently. Then apply  
McLube, then follow with easer (which tapers the hole). Having  
determined how deep the easer needs to go, you can "lock" a finger to  
the upper end of the easer (the part that is inserted through the  
button) to act as a "positive stop" against the top of the button. And  
then go through a whole set very rapidly.
	New balance holes often benefit from being reamed. A lot of times  
they have quite a bit of loose wood fiber, and often they are just  
plain too small. So we get into a syndrome of easing with the easer,  
swelling with steam, easing . . .  every time we rebush or re-size the  
bushings. If it is sized right - and that needs to be pretty precisely  
- there is a lot less work over the years.
	BTW, bottoms of balance pins can be quickly lubed with ProLube  
applied with a brush: hold the keyframe on end, and swipe the brush  
along the whole line from bass to treble. One swipe for naturals,  
another for sharps. Tip courtesy of Eric Schandall, who also  
recommends doing the same to tops of balance pins and to front pins.  
He prefers ProLube to McLube because of health/environmental reasons.  
I won't argue with that, though I think that McLube does a better job  
and lasts longer - for metal and sometimes wood. Our HVAC system makes  
sure that fumes don't linger long.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu