I posted: >"This comes from hanging trial hammers in the middle of the section and > >moving the action in and out to find the best contact point on the string." Alan writes: >Moving the action in and out? >I've seen curved hammer lines to accomodate the dampers. What does that >do to ideal strike points? (Hmm, I must apologize for not stipulating that I was referring to grand actions, the upright action must be raised and lowered to analyze the same question.) On a Steinway grand, the hammers are usually hung 130 mm from the center pin. So, it is a simple matter to have a set of trial hammers, of varying bore lengths, hung at this distance, at exactly 90 degrees to their shank. I use them find what bore distance allows the hammer to meet the string at 90 degrees. ( I do this with a small square on the strings against which the hammers, with their centerlines marked, are compared when they touch the string). Then I bore the set and install the end hammers in each section at 130 mm. I put the action in the piano and listen to changes as the action moves in or out. If it improves the sound of a section to pull the action out 2 mm, I simply hang the hammers in that section at 132 mm. Sometimes I find that the middle of a section needs to be farther out than the ends, so I make a note of this and hang by the following procedure: In the upper sections, I put a hammer in the middle of the section and listen as it is moved in or out. This is where I find that hammer lines can produce better sound when curved within a section, but it usually turns out that the curve is gradual within any given section. Separate sections under the V-bar usually have their own distinctive "best" hanging distance. These curved hammer lines are not easily replicated on jigs with straight edges, so I usually have one or two hammers within the section that are indexed to the optimum contact spot, and then hang the hammers in straight lines between them. At some point, the time it takes to refine the contact points to the last 1/2 mm is not worth it. Hammers can be finely adjusted to these tolerances with a little heat and a vertical bend in the shank, if necessary. Even a very slight asymmetry in filing can move contact back or forth, so I just hang straight between guides that are perhaps 10 hammers apart. I also begin a replacement job with the hammer shanks all traveling straight up and down, as measured by a square sitting on the whippen rail. I space the shanks to begin their arc from directly over the whippen flange screw and with equal distance between them at the knuckle. This provides a beginning alignment "framework" so that when decisions have to be made, I know where I can safely depart from "ideal". I often find that grands require the bass hammers to be moved leftward, and the middle section must be spaced to the right if I am to have all the top end directly under the strings and directly over the whippen. By starting off with everything straight, I know how to split the difference so that nobody is way off center,(which would require excessive spacing of whippens, which leads to problems if the capstans are not perfectly aligned, and the same goes for the let-off buttons). I hate to burn shanks,(though I do), so I really want to know that they are traveling straight before the hammers go on them. Also, especially in regard to Steinways, once I know that they are traveling straight, I know that I can space them with two equal-sized shims of brown paper tape used on the diagonal and not change the traveling. This is, ultimately, a time saver when the greatest degree of perfection is the goal. Sometimes it helps the speed of Steinway regulation to combine the spacing and traveling, ie, if you know the hammer needs to strike farther to the left, and it is traveling to the right, a simple spacing paper on the right side of the flange will cure both at once. And, if it is traveling right, and hits the string just right, the Steinway flange allows one to shim just the front right corner, so that the shank travels more to the left, but the flange is swung to the right, keeping the contact correct, while making the hammer travel straight up. Regards, Ed Foote RPT
This PTG archive page provided courtesy of Moy Piano Service, LLC