RustRazor Jim and list, Jim Coleman, Sr. wrote: >A couple of years ago I dealt with this problem of Baldwin rep springs. >The generic problem is one of spring-rate. . . Since this spring is >so short, the >presure changes too much when it is actuated. It is necessary to have a >quicker rise of the hammer from check in order that the spring will >still be strong enough to support the hammer at rest. This is something which we discovered also when designing our new grand piano action. The first prototype wippen had just one spring coil on the spring, causing the spring rate to be too progressive. The final design has two spring coils to produce a more uniform spring loading during the depression of the repetition lever. A drawing of our action can be found at; www.overspianos.com.au/actn.jpeg While the spring arm is quite short on our action, the two-turn spring coil allows the spring rate to be relatively uniform. the lower spring arm on our action is deliberately positioned on the line between the repetition lever and jack centres to minimise friction losses (if you check the contact of the butterfly spring with the repetition lever slot, you will notice that there is considerable friction between the spring and lever during lever depression). Regards, Ron Overs -- _________________________ Website: www.overspianos.com.au Email: ron@overspianos.com.au _________________________
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