Dear Roger, I've learned alot in the Hundred or so assist spring retrofits I've done myself and with the help of my agents over the years. So I'm going step in an make a few comments in support of helper springs. >...The main problem is that as time goes by, the springs >get weaker, and the piper has to be paid. We've always used copper berylium springs made by Renner and we have not seen substantial weaking of the springs over time. When initially adjusted they loose some tension then stabilize after a few adjustments. In Hamburg Steinway actions from the twenties that we've studied the springs are still working as hard as the day they were adjusted over half a century ago. There are two big problems with the way these springs have been used: 1. Piano makers weigh off the keys with the assist springs engaged without regard for the spring tension. This creates very uneven front weights. If you look at the graph on the cover photo in March 2000 Journal you will see a graph of front weights from a factory weigh off of a Petrof. Note three grouping of front weight corresponding to the bottom section with heavy assist springs the mid section with lighter springs and the top section with no springs. We recommend weighing off with the springs disconnected then connecting and individually tensioning to make the final balance weight. (we install adjustment screws to make this task easier) 2. Many piano makers use the springs to take as much as 50 grams off the touch weight. This causes "Bouncy Key" and repetition problems. > The springs should only adjust up to about 5 gms. We take as much as 25 grams off the touchweight, using a 0.7mm diameter spring, without ill effect. Usually we design the springs to take around 18 grams. The old Steinways that were adjusted to just support the weight of the just the wippen take about 10 grams off the balance weight. >You could make some new springs out of #20 swg piano wire,... We'll weight until your test results ar in... :) David C. Stanwood
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