Terry: << My question revolves around re-weighing a keyboard.>> Actually, as you point out, your question involves the entire action. The variations occur all over the place, in the keys, the action; Sure, improper leading should not compensate for gross errors in the action - but you need to find these problems and fix what you can, or you will still be overcompensating with lead in the keys, and the action will perform poorly - with gross variations in down and up weight, as you described earlier. Excluding the top action will prevent you from finding important causes of touchweight problems related to leverage, such as knuckle placement, hammer weight, and although key related - whip foot/capstan placement, and irregularities in any of the above, for starters. Understanding the levers in the action, and refining these relationships - Stanwood's articles thoroughly cover this, and the archives have plenty to say. Friction and parts weight are important, and understanding the geometry is helpful (the coinciding arcs principle - tangenting circles), but you have to analyse the action as a lever and understand how to rectify problems you find. This action may have significant leverage problems. Hopefully, you will find these, and you may end up removing some key lead (excess mass/inertia) as well. Stanwood's own method of calculating smooth front weight specifications is patented and requires working with one of his licensed technicians, but his articles provide the basis for a thorough understanding. Check out these articles in the PTG Journals: "Mastering Friction with the Balance Weight System", October 1990, "The New Touchweight Metrology," PTG Journal, June 1996, "Standard Protocols of the New Touch Weight Metrology," PTG Journal, February 2000, "Through the Eyes of the New Tough Weight Metrology Metrology," March 2000. Bill Shull University of Redlands, La Sierra University, I have been trying to find a good resource for a description of an effective methodology for weighing-off a keyboard. I have had little luck. My assumption is that established procedures follow: Get hammers in good shape (new or filed, etc.), get all friction components to acceptable levels (within a few grams of each other), and regulate the action. Then, with the action in place, put your desired gram down weight on the end of the key and balance the key with various desirable combinations of key leads. Re-test the down weight and up weight to be sure you are where you want to be, readjusting the key leads as required. It seems to me that you would always have a great potential for a several gram error that way because of friction variations from note to note (which is going to be continually changing), and because of the one or two gram error inherent in measuring down weight and up weight. Is it possible that the following method would yield more consistent results? 1) Be sure that excess friction in key bushings is eliminated. 2) Identify several notes at both ends of the keyboard that perform ideally (your call) with regard to friction (ideally #1 and #88 - and be sure they are properly regulated) by precisely measuring up and down weights. 3) Record the measured up and down weights of these notes (realizing that they may be higher or lower than that desired). 4) Remove action stack. 5) Place round tube (plastic or metal pipe about 1" tall) over capstan of one of the ideal notes. 6) Set weights upon capstan (actually on tube) such that they exactly balance the same down weight (measured in step 3) of that note. Do the same procedure for the other notes measured in step 3. These should be consistent, varying only with varying hammer weight. 7) We have now accurately replaced the action weight plus an ideal friction component with the weights resting upon the capstan. After doing this at both ends of the keyboard, a simple mathematical calculation will provide the idealized action weights (at the capstan) for all 88 keys (you will need to do this process twice - once for the naturals and once for the sharps because of differing center rail pin locations causing different key leverage components). 8) Remove old key leads and properly plug. 9) Place the idealized action weights on one capstan at a time, place your desired down weight at the end of the key, and balance with appropriately placed lead key weights (each key lead should be the weight of your intended key leads less the weight of the wood plug that will be removed during key lead installation). Mark key lead locations. 9) Install new key leads. Now you have a set of keys that are weighted independently of any variations in action friction from note to note (which will always be changing anyway) and the small inaccuracy associated with measuring down weight (it seems to me that is always an opinion call within perhaps two grams - if you balance a nearly frictionless key, you can repeatedly do that to within one gram). Am I like way out in right field or do these thoughts seem to have any merit? Can anyone recommend a resource for an excellent methodology? Terry (can't blame a guy for thinkin') Farrell Piano Tuning & Service Tampa, Florida mfarrel2@tampabay.rr.com >>
This PTG archive page provided courtesy of Moy Piano Service, LLC