Piano Ac On Regula On - QRS Music Technologies QRS PNO3 Installation Manual

This discussion is not intended to be a complete course on grand ac on regula on, but rather may prove helpful in restoring the ac on to proper performance. Proper
alignment of ac on parts, and key easing are all very important steps in the regula on procedure. The following procedure assumes that this preliminary work has been
checked and performed as necessary. Before removing the ac on from the ac on cavity, evaluate ac on regula on. If the ac on is not well regulated, proper perfor‐
mance of the system cannot be expected.
During the installa on process of the PNOma on II Player System, it is quite possible that ac on regula on will be directly affected. A por on of the keyframe and back
rail cloth will be removed so that the note solenoid plungers can contact the keytails. This opera on may cause the keytails to be lower than their original posi on. The
result of lower key tails is an increase in both key height, and hammer strike distance. Restoring the strike distance to specifica ons by turning out the capstan screws is
not the proper remedy. Always re‐work the back rail height so that the key height is at its original posi on.
‐ Are the keys level?
‐ Do the hammers let off 1/8 in the bass, tapering to 1/16 in the high treble?
‐ Is the drop 1/16 below the point of let‐off?
‐ Is the hammer line straight?
‐ Are the hammer shanks approximately one shank thickness above the hammer rest rail?
‐ Is there adequate a er‐touch?
With the ac on on a flat, clean workbench, measure and record the following:
Natural key height at bass and treble ends.
Sharp height above naturals.
Key dip; both naturals and sharps.
The height of the first and last hammers in each sec on of the ac on.
Replace the keys and ac on stack on the ac on frame. Refer to the regula on measurements recorded earlier to see if regula on has been affected by the modifica ons
to the ac on frame. If key height, key level, or strike distance are different than previously recorded, steps must be taken to restore proper regula on.
To restore key height, replace the back rail cloth with one of a thicker dimension. Remove the ac on stack and keys. A er removing the old back rail cloth, be sure that
all traces of glue have been removed from the back rail. Replace a few of the end keys and try various thickness of back rail cloth, without glue, to ball park the correct
key height. Light finger pressure on the capstan screw will approximate the force that is normally on the capstan. Set key height with the back rail cloth at, or slightly
below the desired key height.
When you are sa sfied that you have the best choice of back rail cloth, glue the material to the back rail, leaving the rear edge unglued. Name board felt is available in a
few different thicknesses, and can be used for fine adjustments when glued under the back rail cloth.
Although key height can be reestablished quite accurately using the above procedure, some key leveling is to be expected when replacing back rail cloth.
Remember that subsequent ac on regula on adjustments will affect those already performed. To prepare the ac on for fine regula on, do the following quickly:
Check or set repe on lever height so it is slightly higher than the jack. During your final regula on, trip the jack tender with your finger and release it slowly. If regulat‐
ed properly, you will be able to feel the jack brushing the knuckle as it is released. The jack must return completely under the knuckle.
Set strike distance to 1 3/4. Be sure that hammer shanks are above the rest rail.
Check or set jack posi on so that the back edge of the jack is aligned with the back edge of the knuckle core.
Set let‐off 1/8 from string in the bass, tapering to 1/16 in the high treble. Make sure that you have some drop a er escapement.
Set drop to 1/16 below let‐off.
With the above preliminary steps completed, level keys as necessary to their final specifica on. Note that with key height at the same specifica on as it was before ac‐
on frame modifica on, key dip should be correct (assuming that the dip was correct prior to the installa on procedure). Also, damper li ming is reestablished.
Check or set repe on spring. The spring should carry the hammer upward with a steady mo on, without kicking.
With the preliminary ac on regula on done, you are ready to establish the strike distance and key dip measurements that will result in proper a er‐touch. Since the key
height/key dip rela onship has been reestablished, consider varying only the strike distance to get the proper a er‐touch. If you are working on an older instrument,
consider varying both strike distance and dip to arrive at an acceptable compromise. Select sample keys with which to work, like the first and last two keys in each sec‐
on.
Depress your first sample key very slowly, stopping its movement just a er let off. Look to see if there is addi onal key travel le . If there is no addi onal key travel
a er the let off point, there is no a er‐touch. Key dip will have to be increased, or strike distance will have to be decreased. If there is too much addi onal key travel
a er the let off point, the hammer may block against the strings when the key is played fully into its dip. Key dip will have to be decreased, or strike distance will have to
be increased. Be sure that the sharps have the same a er touch as the naturals. As a second check, see that with the key fully depressed, there is s ll some travel le at
the jack tender.
When you have the key dip/strike distance established on your samples, set your key dip to your established specifica on uniformly throughout the ac on. You are now
ready for the final regula on.
Using your new strike distance measurements, carefully repeat the above outlined steps for the final me.
Introduc on
Piano Ac on Regula on
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