The Piano Technicians Guild

The mission of the Piano Technicians Guild is to promote the highest possible standards of piano service by providing members with opportunities for professional development, by recognizing technical competence through examinations and by advancing the interests of its members. Last evening I hosted our local chapter of the PTG at my shop. This a great group of guys that are interested in providing excellence in their piano work in their respective communities.

A regular feature of our monthly meeting is the technical portion. This month it was my turn to do the technical. I chose the topic Grand damper installation, as that is a project I am presently working on. The out line posted below connects with the previous posts on Grand damper installation.

S. Central PA Chapter PTG
February 24, 2009
Grand Damper Felt Replacement

1) When do you replace damper felts?
a. Old felts are contaminated
b. Old felt are hard from age
c. New strings are installed in piano
2) Preparing for damper removal
a. Check existing operation
i. Lift timing
ii. Buzzes, rattles, etc.
b. Measure underlever height from keybed
c. Number dampers as you remove them
d. Place in rack for easy handling
3) Related repairs
a. Guide rail felt replacement
b. Underlevers/back action
i. Remove and clean
ii. Check pinning
iii. Check lead weights
iv. Check flange glue joints (old Steinways especially)
v. Replace?
c. Lyre, pedals and trapwork
4) Removing old felts
a. Options
i. Dry- be careful not to remove wood
ii. Wet- be careful not to damage finish
b. Measure and count
i. Type of felt- Mono, Bi, Tri wedge, Tri flat
ii. Length of felt front and rear- are not always the same
iii. Configuration of felt- tri-tri, tri-flat, flat-flat
5) Preparing heads for new felts
a. Clean any remaining glue residue
b. Polish wires- Noxon polish
c. Refinish heads
6) Installing new felts on heads
a. Use only quality felts
i. Horizontal grain
ii. Even and centered cuts
iii. Proper thickness
b. Cut to proper length
c. Backing felt?
d. Glue on heads before installation
e. Center and align
f. Glues- Hot hide or Titebond Molding & Trim
g. Recreate original “scale”
7) Installing dampers in piano- Illustrated in piano
a. Reinstall back action and upstop rail
b. Setting underlever height with height gauge
i. Single lever gauge
ii. Gang gauge
iii. Ballast
c. Spacing heads
i. Centered side to side
ii. Perpendicular to string plane
iii. Front to back
d. Even lift
i. Timing- engage at ½ key stroke
ii. Rotational travel
iii. Linear travel
e. Tools needed
i. Duck bill pliers
ii. Needle nose pliers
iii. Wire bender pliers
iv. Hart damper tool
8) Trouble shooting
a. Bleeding dampers
b. Fine tuning lift
c. Winking dampers
i. Rotational
ii. Front-back
d. Pedal adjustment
9) Finishing up
a. Reinstall soustenuto
i. Realign tabs if necessary
1. Height
2. Front/back
b. Reinstall action
i. Recheck
1. Timing
2. Damping/bleeding
10) Take a break and marvel at your fine craftsmanship