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65 grams weight for key balance

65 grams weight for key balance

SKU: 7291-1
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Instructions for Key Balance Optional 65 Gram Ring.

Purpose – To extend the measuring range of the Key Balance to measure and diagnose damper spring tension from the front of key. 


1) measure the action downweight (sustain pedal depressed)

2) measure action system and damper system downweight (sustain pedal released)

3) combined weight minus action weight equals damper spring resistance weight

Using the Ring Conversion Scale – Slide the 65 gram Ring over the brass stub and position over the key that is being tested. With the damper engaged (do not depress the sustain pedal), slide the indicator in the normal manner until the key stops at the point of, but not beyond, escapement. Take the reading on the scale. Use this number on the left side of the conversion chart affixed to the ring. The scale is in 5 gram increments. If your measurement is in between, please refer to the chart below. This is the combined value of both the action and the resistance of the damper spring.

This is a diagnostic tool. You may subtract the down-weight value from the combined value to determine damper spring resistance at the front of key. In general, if the damper spring alone is as strong, or stronger than the action down weight, then the damper spring tension is likely too high for smooth regulation and adds unnecessary touch weight.  

Example: If action down weight is 50 grams, and combined weight is 120 grams, then damper weight alone is 70 grams. This would indicate heavy damper springs.  (Please note that damper spring tension readings at front of key will be different values than readings taken directly from the damper or damper lever.)

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Pianos Bolduc, manufacturer of fine piano components, maker of specialized tools, and major piano re-builder distributes parts and supplies for piano technicians and rebuilders around the world. This catalogue has been specially designed to serve piano technicians, re-builders, and manufacturers. For technical advice, please do not hesitate to contact us by e-mail (