Mark When deciding whether to use angled capstans and angled wippen cushions one needs to realize that the point of interface is actually two arc shaped surfaces coming into contact with one another. In the case of non angled capstans, they are in contact with a non angled wippen cushion and the two arcs have the "best possible" interface. The problem with mixing angled capstans and non angled wippens comes in the fact that the two arc surfaces are now not in their ideal position with regard to one another. There is very little difference in whether the contact points are angled or non-angled as long as these two surfaces have the best relationship to one another. There will be scuffing and movement from the initial contact point to the final contact point when the key is depressed. Regarding the different heel configuration on the sharps one must analyze the actual ratio of the keys to the balance pins to the capstans and compare how closely the manufacturer actually matched the key ratio. Some manufacturers are very diligent to make the key ratios the same between naturals and sharps and others simply assume that the balance rail pins are "always a set distance from one another!" All actions change the ratios during the various points of travel. The best measurement is to introduce a known key travel and measure the hammer travel from rest. These distances will give you the action ratio. It can be quite interesting to compare the action ratios between the naturals and the sharps on any given piano action. There can be as much as a half a point difference (i.e. naturals action ratio of 5.5: 1 and sharp ratio of 5:1). I would recommend that you measure the existing action ratio on both the naturals and sharps and then decide if you want to try to match the original set up with the new wippen/heel combination or want to more closely match the action ratios of the two by experimenting with the wippen/heel combination to even things out. A very easy jig for measuring the action ratio can be made by taking a small flat block of wood long enough to span at least three keys. Glue some front rail punchings to the center of this piece of wood that give a combined height of 5 mm. With three level keys (either natural or sharps) and hammers even height from the rest rail/cushion, one simply depresses the center key with the block jig and measures the hammer travel from rest. The hammer travel, measured in mm, can be divided by 5 to give a basic key ratio. The stackable weights from the supply house that are never accurate can be used to keep the center key depressed while you measure the hammer travel. Hope this helps. Norman Cantrell, Registered Piano Technician --- On Sat, 5/8/10, Mark Dierauf <pianotech at nhpianos.com> wrote: From: Mark Dierauf <pianotech at nhpianos.com> Subject: [CAUT] Capstan relocation questions To: "College and University Technicians" <caut at ptg.org> Date: Saturday, May 8, 2010, 10:42 AM I'm getting ready to install my second set of the WNG composite reps and wanted to get a sense of the current thinking about the interface between the capstan and the rep heel. I'm interested in two things in particular. Angled or straight capstans? The original 20's vintage S&S A had angled capstans of course, and I've read some references to this creating an action ratio which varies throughout the keystroke. I tend to credit the original designers with more thoughtfulness than they're sometimes given credit for, as they had an awful lot of pianos (as well as time, inclination and money) to experiment with. So part of me thinks that if they used angled capstans they probably did it for a specific, well thought out reason. Of course, the new WNG heels are not angled to match, which might in itself be a good reason to go with non-angled capstans. On my first set I used a 6º angle, arrived at by trial & error, and this seemed to work out pretty well, but I'm wondering if anybody has any good reasons to go with one system or the other. The "magic line" at half-stroke: WNG is recommending using different heels for the sharps to maintain this, but I'm a little concerned about how this will actually feel in the finished action. After all, pianists have spent the past three centuries getting used to slightly different touch characteristics between sharps and naturals, and I want this action to feel good, not unusual. The only other time I did this I set the magic line up for the naturals and let it go at that. It occurred to me that it might be better to compromise between the naturals and sharps, or else go with the two different heels. Has anybody used the WNG system and been able to judge the results in the finished product? Thanks, - Mark -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut.php/attachments/20100508/6e971d14/attachment.htm>
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