Upright plate bolts

[Keith Roberts]

I have a 1911 A. B. Cameron upright, (given to me). As part of my continuing
education  I am doing various projects that I get to see the immediate and
long term effects of each project. I tightened up the plate bolts and
screws, (the ones behind the strings were the loosest), and what a
difference in the sound. The tubby sound all but dissapeared. However, there
is a stud that comes out of one of the back posts, through the sound board
(not attached to), through the plate with a large square nut on it and no
back up nut under the plate. This is located below the hitch pins for D5.
There is also a screw that does the same thing on the post to the right and
is below the hitch pins of note B6. It appears to me that this might affect
the downbearing on the bridge and the tension of the soundboard. What is the
purpose of these, and how do I adjust them? Should I rely on my mechanics
wrist and elbow function that tells me when it's tightened to the max torque
just before failure? Thank You in advance.

Keith Roberts
Associate PTG