Adjusting the piano key-weight: Weighing up and lead loading

Weighting the keys and installing lead weights

Marking off individual keys with chalk prior to drilling.

Drilling in preparation for inserting lead weight.

Inserting weights

Checking the desired result by by lead loading

Lead Loading 20 Grammes Upweight

Lead loading 56 grammes downweight

piano key weight gauges and lead weights

Various key weight gauges and lead weights.

I am extremely happy with Tim’s work. He is a piano technician of the highest quality. Ten years ago he completely replaced the action on the August Foerster piano I have had since childhood.

Recently I bought a new August Foerster. I prefer to have a heavy touch to the keys. This is important for me since I am a piano teacher and this enables me to spot more easily the errors in my students’ touch. With Tim’s help I decided that 58g was the best weight. Tim came and loaded the keys to that weight. I was impressed by the speed and precision of Tim’s work. And his work is very reasonably priced. The result was excellent. I am now much happier with the piano.

Thanks Tim. Great work!

Elza Lusher, Egham, Surrey

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Pianos are usually designed to have an even key-weight throughout the compass. This is arrived at by having a minimum up-weight of 20 grammes as the starting-point, and working back from that (because unless a depressed key can push up at least 20g, the repetition will be terrible). In a well-designed action, a down-weight of 48-58 grammes will give a brisk up-weight of 20 grammes.

That’s the ideal, but the reality is often different. Perhaps the piano had new hammers fitted at some point and the key-weight wasn’t adjusted afterwards, or perhaps the key-bushings and felt bearings - called ‘centres’ - have tightened with moisture or lack of use, or maybe the keys were not weighed up at the factory at all.

Whatever the reason, we have all, as pianists, from time-to-time had to play on an instrument which was so light to the touch that our fingers ran away with us, and sometimes the keys didn’t return properly to their normal resting point - and at other times we've had to make something of a piano which was so sluggish in the touch that it was like playing through thick treacle. Exhausting, both conditions.

The remedy is to check through all of the centres in the piano’s action, and ease its keys, to ensure the correct tolerances and frictions - and to polish balance pins on the key-frame and lubricate certain leathers and felts with french chalk. Only once all this is done can the action and keys be assessed in terms of weighting, by means of ‘taking a reading’ with an adjustable weight and individual lead key-weights. Take a glance at the pictures below, and you will see the keys being measured for weight, marked with chalk for the insertion of the lead weights, drilled individually to accept these new weights, and then having them inserted.

Sometimes a pianist will have his or her individual requirements; recently a client asked me to load her piano keys to give a weighting of 58 grammes throughout; quite a heavy down-weight, but the upside was that the up-weight, and therefore repetition, became tremendously good.

Contact Tim Hendy

Member of the Pianoforte Tuners’s Association since 1993

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