Action Rail Screws

[Piano Boutique]

William,

Having just answered your post, It will probably come up in my future, but 
here goes.

In the past there were times that they hand turned screws, and there threads 
differed.   The biggest concern was plate lag bolts that could not have as 
good a grip if the threads differed.   Having said that, today it is 
becoming less often we find pianos this old, and if it is action screws: 
well it doesn't have to do with so much stress.

Just what I have heard.

William



PIANO BOUTIQUE
William Benjamin
The tuner alone,
Preserves the tone.