Hi, All, I was asked if I had any of David Stanwood's recent hammer weight data. Unfortunately I do not but he has developed some reliable figures empirically, by measuring many piano's hammers and deriving standards by determining the actions over or under weight. In David's scheme he will weigh and adjust the weight of each individual hammer. By weighing the weight from the center pin to the strike point he gets the strike weight. I have some .250" solder I use for letting into the moldings. Sanding for going the other way. Taking more than a gram of weight off a hammer is a real challenge. I lift the flange so it is 90 degrees to the shank and rest the flange pin end on a half round hammer shank taped to the damper height gauge found on the string height gauge located on page 14 of APSCo's new catalog. The height adjusts so the shank is horizontal. I then rest the hammer heel on an Auhous model C-305 digital scale from Metric People 800-426-8356 $125 (use David's name for the discount). The scale's range is 0.0 to 300.0 grams or about 10.8 ounces. By graphing these "Strike Weights" you can see the useful- ness of knowing what the weights are. The keys are weighed from the center of the balance pin hole to 1 cm from the front end of the keys. I have made little fixtures the keys rest upon to make this chore go faster. By measuring the up weight and the down weight you can calculate the "Balance Weight" of the action. A 50 gram down and a 25 gm up will have a balance weight of 37 grams. A nice slightly over weight. Additionally (50 gm minus 25 gm)/2 will partially reflect efficiency and/or friction of the action of 12 grams which is nice and average. These numbers help you find over and under friction points of the action. More about this later. The Europeans have, for over a century, used wippen helper springs mounted at the wippen flange. These springs serve to lower balance weight significantly and to reduce the amount of lead needed at the fronts of the keys. Most American technicians have little understanding of these springs and what they can do for the pianists. David has developed techniques for adding springs to any current action so that the touch weight of the action can be controlled by adjusting the tension of the spring. David has introduced friction control screws into the hammer shanks so that a sliver of wood at the bottom of the hole bears on the felt bushings. Introducing one point of friction control makes it possible to control the friction of the entire action. This friction can be adjusted in about five minutes when the need arises. If you send the balance weight, front weight and strike weight of all C notes and C# notes to David he will return a set of weight specs for the strike weights and the front weights specific to that action based on your requested balance weights. This will control the inertia of each hammer and each key so that the action feels incredibly smooth. This leaves one other uncontrolled factor, geometry. By putting weights on a key with the hammer off the wippen so that the key is absolutely perfectly balanced then lowering the hammer and taking the up and down weights one can measure the leverage of the entire key unit at that note. David may relocate the capstans to bring an action into compliance. David has just promised to send me a text file to be posted here in the near future providing much more specific information. He can also be reached at 508-693-1583 if you need more informa- tion now. David uses a set of gram weights that range from 15 to 65 grams. These come in a box with trays to arrange them for what different balance weight setups. I do need to point out that David sells information and provides the services of friction screws, spring installation if you send him the action parts. He will initially adjust the spring tension so you will have little of that to do at comple- tion. Well, I think I have covered most inquiries in too much detail. If there are further questions just post them along. My experience has been that the more extensively detailed actions become the favorite of the students and faculty to the point that they are now demanding better pianos to practice, teach and perform upon. It takes an ungodly amount of time to do all this work. David has workstations for each operation that makes it go FAST whereas I am using a Crapsman drill press which has to be jigged up every time. A royal pain. I did a complete modification (except capstan relocation) on an out of the way practice room Kawai KG-2C and without advising anyone (except one professor and Robert Toub) I have found that it is ALWAYS in use. The kids know nothing about it except that they like it. If I have the time I would like to do every piano and sit back and bask in the glory and accolades. As it is I get too many complaints that the pianos are not good enough. You can never win :*(. I think the idea of using the CAUT meeting in Alburquerque on this extremely timely and useful information a good idea. Thanks for suggesting it!!! There is more and other information out there than just Davids and I am most interested in learning how to make actions as good as I can. Newton J. Hunt nhunt@gandalf.rutgers.edu
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