1.  Addition to Spurlock Damper Underlever Jig - A Tuesday Tech Tip

Posted 11-21-2017 09:53
Good morning techs,

Retiming dampers is something that we do on a very regular basis. Our tool of choice is the Spurlock Damper Underlever Jig (either the production version or my homebrew that I built on Bill's designs but before he started manufacturing them.) On some pianos, particularly some with damper spoons, the correct position of the damper underlever is higher than the jig will adjust.

To accommodate these instruments, we've tried setting the jig on various props to get it up to the right height. We also played with longer screws to replace the feet but that is both slow to change and puts a lot of wear on the threads in the rail. After thinking about it a little further, we came up with an idea that is simple, cheap, effective, repeatable, and accurate: a piece 3/4" square tubing that is then clipped to the aluminum regulating shelf with small binder clips or drilled and tapped to be held to the regulating shelf by two 8-32 cap screws.

Here we have the tool without the extension:
damper underlever jig without extension
The tool and the extension laid out on a keybed:
tool and extension
The tool and extension in place under the underlever spoons:
damper took with extension
Have fun with this one and have a Great Thanksgiving!

Allan Gilreath, RPT
Registered Piano Technician & President
Allan Gilreath & Associates, Inc
Calhoun, GA
allan@allangilreath.com - www.allangilreath.com

2.  RE: Addition to Spurlock Damper Underlever Jig - A Tuesday Tech Tip

Posted 11-21-2017 20:14
Thanks for sharing your fix Allan.  

Gary Bruce
Registered Piano Technician
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3.  RE: Addition to Spurlock Damper Underlever Jig - A Tuesday Tech Tip

Posted 11-22-2017 13:38
I thought you were supposed adjust the height of the underlevers uniformly and then adjust the spoon. I have a jig that sets the underlevers evenly and then tweak the spoons across the compass and then individually as needed, especially for the dampers at the bass/tenor break.

The u/l's need to be uniform for the sostenuto to function without problems.


Jon Page

4.  RE: Addition to Spurlock Damper Underlever Jig - A Tuesday Tech Tip

Posted 11-22-2017 15:41
The spoons ARE the underlevers.  Unless they've been seriously modified, a consistent spoon level should produce a consistent sostenuto tab height, or close enough to be able to refine with paper shimming.   Any method employing a jig keyed to samples pre-supposes that parts are consistent: lifter felts, damper tray felt, tabs, etc.   My instinct would be to use Allen's approach (again, if spoons are un-distorted), and then use capstans (if there) to refine sustain (tempo) pedal lift.  This is not what the  Kawai Shigeru manual advises, though the last steps leave me baffled, as it would seem to alter the damper timing with the key in order to have consistent lift with pedal.

Initial Damper lift
Adjust pedal rod head to set the sample damper
levers so that they start moving when the hammer
is 23mm (1/2 blow distance) from string.
Tighten damper wire screws for sample damper
levers in each section.
Reinstall the action and check the damper lift.
Once the samples are set, tighten all damper wire
screws, then remove paper punching and correct
the damper head alignment

Damper lift with Pedal
Once dampers are tightened and aligned, recheck
the dampers for even lift with the damper pedal.
To adjust, loosen the screw in the damper
top flange and move the lever up or down.
*Do not use the capstan screws for this adjustment

David Skolnik
Hastings-on-Hudson NY

5.  RE: Addition to Spurlock Damper Underlever Jig - A Tuesday Tech Tip

Posted 11-22-2017 18:47



Your list leaves out some steps from the Shigeru instructions.


  • Loosen damper wire screws
  • Insert 2mm shim between the pitman and the damper tray (this will provide lost motion in the pedal later)
  • Adjust pedal rod to set tray for correct lift with the key in a sample note
  • Level the damper levers on the tray using the lever capstans.  This is what sets even lift with the keys. It can be refined later using paper shims if the key end felts are worn or otherwise uneven. This also provides even sostenuto tabs, as the tap stop felts are quite firm and even.
  • After the levers are leveled for key lift, then snug up the wire screws.
  • Remove the 2mm shim from the pitman, and check for even lift with the pedal. Correct any errors using the wire screws, not the capstans, as the capstans have already been set for even lift with the key and sostenuto.


I hope this clarifies it some.


Don Mannino

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