Hi Ric Hey good food for thought but if 1 mm of key movement raises the hammer 6mm , to me that is a 6 to 1 ratio. When I use the spurlock tool all I'm doing is using it as a quick trouble shooting indicator as to how much trouble the action is going to be. Ie will longer knuckle to center be required or capstan move.. As you stated this morning. Ed ...I like your thoughts too. The use of smaller than a 6 mm block takes us in the direction of action acceleration. Dale Erwin Hi All As long as we all remember that the <<ratio>> defined this way (ala Spurlock) is not the same ratio relationship as Stanwoods Strike Weight ratio we are ok here. Stanwoods ratio is about how much weight at the key front is needed to balance whatever radius weight the hammer has out there on the end of that shank. More specifically we are talking about how much weight would be needed to bring the action into the half blow condition in a frictionless world. That is not at all the same thing as how much distance the hammer moves for any given amount of key travel. In fact, if you were picky enough about your measurements you would find that if you measured for a 8 mm key travel compared to 4 mm key travel you'd end up with two different figures there too. There is an approximate translation that generally works fair enough... and in any case if you are shooting for some BW in an action re-do you nearly always end up within a couple grams (nearly always heavier) if you've calculated with the distance ratio as your figure for R. Its a good thing to gain a basic idea of your general leverage zone by doing the Spurlock thing. But if you plug that value into Stanwoods formula to arrive at a FW figure for some targeted BW, you are going to have to go back and add some few grams of FW in the end. On the other hand... the error created is consistent... so you can either live with it and still have an even result... or try and compensate a bit by approximating a translation from one R to the other. Cheers RicB -------------- next part -------------- An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20061126/4feda4a2/attachment.html
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