Regulating Key-Dip

[Jon Page]

Although you said that you didn't have problems with the regulation,
I'd still like to address a few points and eventually get to your question.

SInce the hammers are worn, the blow distance probably is incorrect.
It should be 1 3/4" sometimes 1 7/8".

So if you shim the rest rail to raise the hammer line, you will also have
to reduce the lost motion via the capstan. But wait...  The damper felts
have compressed as well and are more than likely lifting too early.
Shortening the blow and raising the capstans could cause the spoons
to lift the dampers off the strings with the whippen at rest. Not good.
So be prepared to adjust dampers spoons. Have the dampers lift
evenly with the pedal before you do though.
Cautionary note: if the dampers are lifting really late in the bass,
there's a good chance that the pin block is pulling away from the back.
On an old vertical, it's always a good idea to check that aspect.

As previously mentioned, key dip should be 3/8"+ (I use a .390 block)
Sharp height is 7/16 to 1/2 " above naturals, whatever sharp height
keeps the keystick at a similar incline to the naturals unless some
ultra thick plastic replaced the thin ivory. (Bear in mind the bottom
of the fallboard). As to exactly how much dip is required, it's a balance
between blow distance and letoff to get the jack to clear the butt
sufficiently.

The way to determine the dip on the sharps is to first set the dip
on the naturals. With the lost motion attended to, set the naturals'
back checks to proper check distance and then set all backchecks
in a straight line. Then set the dip on the sharps such that they
check in identically to the naturals. Now your dip is even.
With the back checks even, sufficient dip on the sharps
will produce equal checking.

At this point you might as well adjust let off.

By the way, with the action out at some point, check the bridge cut-out
at the treble break. The bridge might be binding on the plate. If so,
use a hack saw blade between the plate and bridge to excavate bridge material.
-- 

Regards,

Jon Page