Ron Torrella wrote: > . . . . > > Can't move capstans any more than 3/16" without the capstan contacting > wood. 1/8" would be fine, except it means drilling out the capstan holes > *oversized*, plugging and redrilling. If I didn't oversize the old holes, > drilling new ones would be straddling old and new wood. If I used pine > plugs (not dowels....plugs cut from scrapped keyboards), I *may* be able > to get away with "normal" sized plugs, but there's still a glue joint to > deal with. (Have I started splitting hairs yet?) > > I'm contemplating the option of a combination of things; move the capstans > no more than 3/16" *and* swap small keyleads for medium or large ones. The > net result would be a lighter touch (improved leverage), but a slightly > heavier keyboard (on the order of 150-200grams or 5-7 lbs, overall, is a > guess). . . . ------------------------------------------------ Ron, Although touchweight and action geometry are related, they are not the same thing. Touchweight is the result of some fixed action geometry (that is, a predetermined set of levers working through predetermined and fixed ratios), the accumulated mass of the various parts involved and the accumulated friction of the various sliding and rotating centers. Ideally, the action geometry and specifications are established by some action designer somewhere and this design is faithfully followed by the action manufacturer. In this best of all possible worlds, both static and dynamic touchweight are predetermined by the designer. The action parts -- including the keys -- will all be built to the specification laid down by the designer. Action centers will have some predetermined amount -- or range -- of friction. A predetermined number of key leads will be inserted into predetermined locations in each key. Etc. Etc. Etc. When actions are not built to these standards, there are problems. Sometimes those problems are lever related. It will be impossible to establish the 'proper' relationship between the key travel and the hammer travel. Sometimes the action will appear to be functioning normally, but the piano will very difficult to play. The pianist will complain of a 'heavy' touch even though you may be able to verify that the down weight is right at 52 to 54 grams. Without getting too involved, let me just separate static touchweight from dynamic touchweight. Static touchweight involves only the weight of the parts involved, dynamic touchweight involves the mass of the parts involved. Static touchweight is what is measured by balancing the key and action assembly with a precise mass. Dynamic touchweight is what the pianist feels when the piano is actually being played. Dynamic touchweight includes the inertia of all of the moving parts involved. The action you are working with could be given the 'proper' amount of 'static' touchweight simply by adding more mass to the front of the keys. And this was generally the recommended solution in the 60's, 70's and 80's. At the same time, of course, this made an already problematic action even more difficult to play. What was happening -- at least for the most part -- was that the action geometry had varied from the way it had been designed. And the resulting static touchweight problems were being 'corrected' by adding lead to the keys. The first step with any of these action problems is to verify that the action geometry is correct -- or at least is within a functionally workable range. The device I described is one I used to make the action geometry functional on new pianos without replacing a bunch of parts. At the time we did not have the option of replacing hammershanks and/or wippens. Nor did we have the luxury of relocating knuckles. The problem was generally one of being able to measuring 'proper' static touchweight, but having an action that was 'very' difficult to play due to the large number of leads installed in the keys. A secondary problem was the relationship between hammer travel, key travel and aftertouch. The simple solution was to relocate the capstans. This was done by using the device I described earlier to establish a lever ratio between the key and the hammer that would result in a hammer travel of 44 mm, a key travel of 10 mm and an aftertouch of 1.25 to 1.5 mm. Once this relationship was established, the Teflon bushed (hammershank) action centers were reamed and/or pinned for a friction of between 4 and 7 grams of friction. Following this the action was carefully regulated and then it was finally weighed off. The usual result would be to remove quite a few leads from the keys. Typically -- depending on the model -- we would go from 7 or 8 leads in the low bass to 4 or 5. This whole issue illustrates the problem of individually weighing off each set of keys as determined by the needs of a specific action and keyset combination. This practice uses lead to compensate for variations in action geometry and action center friction. When this is done, even though the action may meet the static touchweight specifications of the manufacturer, it may be a very difficult piano to actually play. There can be -- and very often is -- a great deal of variation in the touch and action response from one piano to the next. A much better practice -- at least in my view -- is to lead the keys to an engineered standard. Then when it comes time to check static touchweight, it will be just that: a check. Now it becomes a verification that the action is functioning correctly. If the action is not functioning correctly, it will give the operator clues as to what is wrong with the action and what needs to be corrected before the piano is shipped. Now, please, don't somebody try to tell me that actions cannot be properly manufactured to this standard. They can be, and it is being done. In my view, this 'feature' -- the need to weigh off each action individually -- is not one to be proud of. It is an indication of a problem, or a flaw, within the manufacturing system that needs to be designed out. Regards, Del
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