Rolling to Pitch

[Ron Nossaman]

> Where is the movement in the string going when it
> can be lowered without tuning any pins?

It's coming from the back scale as you pull the strings 
through the bridge pins with your roller. Contrary to popular 
belief, strings do render across bridges, it can happen 
quickly with big tension differences between front and back 
scales, or slowly over time. I expect you're adding at least 
50 pounds to the string tensions in front of the bridge as you 
roll them, which is enough differential between tensions in 
the back scale, to pull the strings through. You've also put a 
heck of a load at an unnaturally high angle on the bridge 
notch edge during the rolling process, which didn't do the 
bridge cap any favors. After tuning, you left the piano in a 
far worse state of equilibrium than if you had just tuned it 
as you found it, because back scale tensions are still likely 
higher than they were when you got there, and will slowly more 
nearly equalize as the string creeps across the bridge with 
minor temperature and humidity changes breaking friction in 
small increments and letting it move. That will pull the front 
scale sharp again. It's getting less stable as it ages, I 
think, because the wearing bridge pins are presenting a larger 
contact area to the string, increasing friction, and making 
rendering through the bridge less likely with each passing 
year. So you're leaving a less stable tuning, on average, each 
time it's tuned. This isn't an uncommon thing in pianos living 
in rotten climate control conditions, where big pitch changes 
are necessary with each tuning. Go back and check it in a 
couple of weeks and see how it sounds. I expect you've got an 
unpleasant surprise waiting. Meanwhile, throw that roller 
away. <G>

Ron N