Piano Quality Control & Assurance 2 — Questions and Answers
Question 1: When voicing a piano hammer, what does making the felt harder (lacquering) accomplish?
- Produces a brighter, more penetrating tone (Correct answer)
- Produces a softer, rounder tone
- Increases sustain and resonance
- Reduces string breakage
Correct answer: Produces a brighter, more penetrating tone
Hardening hammer felt with lacquer increases density at impact, producing a brighter and more cutting tone.
Question 2: A piano technician checks for 'lost motion' in the action. What does lost motion refer to?
- Slack between the key and whippen before the hammer begins to move (Correct answer)
- Friction loss in the damper rail
- Excessive repetition spring tension
- Hammer shank misalignment
Correct answer: Slack between the key and whippen before the hammer begins to move
Lost motion is the gap between the capstan and whippen that causes delayed hammer response when a key is depressed.
Question 3: Which QC check verifies that all piano keys return to rest position at the same height?
- Key leveling (Correct answer)
- Strike point measurement
- Blow distance regulation
- Damper timing check
Correct answer: Key leveling
Key leveling ensures all white and black keys sit at a uniform height when at rest, critical for consistent touch feel.
Question 4: During PDI (pre-delivery inspection) of a new grand piano, a technician finds one damper fails to lift when the sustain pedal is pressed. The most likely cause is:
- Damper guide rail set too low
- Broken damper spring
- Misadjusted damper stop rail (Correct answer)
- Worn key bushing felt
Correct answer: Misadjusted damper stop rail
A misadjusted damper stop rail prevents the sostenuto or sustain rod from lifting that damper's lever fully.
Question 5: What is the purpose of 'let-off' regulation in a grand piano action?
- Sets the point where the jack trips away from the hammer knuckle before string contact (Correct answer)
- Controls the speed of hammer return
- Adjusts pedal travel distance
- Regulates key dip depth
Correct answer: Sets the point where the jack trips away from the hammer knuckle before string contact
Let-off regulation sets how close the hammer gets to the string before the jack releases, enabling pianissimo playing.
Question 6: A quality inspector measures string speaking lengths across the bass section. Why is accurate speaking length critical?
- It determines the fundamental pitch of each string (Correct answer)
- It controls sustain pedal travel
- It affects hammer weight
- It sets damper lift timing
Correct answer: It determines the fundamental pitch of each string
The vibrating speaking length of a string directly determines its fundamental frequency and therefore its pitch.
Question 7: Which defect would a QC inspector most likely detect using a consistent finger tap along the piano's inner rim?
- Delamination or voids in the laminated rim (Correct answer)
- Uneven key leveling
- Off-center hammer strike
- Loose tuning pins
Correct answer: Delamination or voids in the laminated rim
Tapping along the rim reveals hollow sounds where glue joints have failed or voids exist in the lamination.
Piano Quality Control & Assurance 2
When voicing a piano hammer, what does making the felt harder (lacquering) accomplish?