-----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of David Stanwood Sent: Wednesday, September 29, 2010 4:32 AM To: pianotech at ptg.org Subject: Re: [pianotech] Voicing the new Mason & Hamlins I'm delighted to see the recent move away from so much hot pressing of hammers. (although I haven't seen such a move in this respect on the part of manufacturers yet..) It's simply a return towards our cold pressed piano making roots. The obsession with power tends to blank out the more intimate and beautiful pianissimo ranges of the piano. You CAN have it both ways! David Stanwood "The art in hammer making has ever been to obtain a solid, firm foundation, graduating in softness and elasticity toward the top surface, which latter has to be silky and elastic in order to produce a mild, soft tone for pianissimo playing, but with sufficient resistance back of it to permit the hard blow of fortissimo playing." - Alfred Dolge ___________________________________ One of the difficulties I have faced in getting manufacturers to even consider backing off on the amount of heat used during the press cycle is their paranoiac fear of losing production speed. The adhesives typically used to bond the felt to the wood molding is thermal-setting; it has be brought up to approximately 80 deg C (or about 175 deg F) for several minutes to cure completely. In the real world, since it takes some amount of time for the heat to migrate through the felt to the adhesive, that means that the side cauls of the press are usually heated to something like 100 deg C (212 deg F) or higher. Indeed, it is not unusual to measure caul temperatures up around 110 to 120 deg. C (230 to 250 deg. F). With heated cauls the press cycle can be as short as 20 minutes. It will take considerably longer that this using a true cold-press cycle. Back in the late 1980s I experimented with various alternative methods of pressing hammers. After a few conversations with Earl Dunlop (then felt technologist for Bacon Felt) and bit of outside research on the subject I came to the conclusion that cold did not necessarily mean cold (just what is the definition of "cold" when it comes to pressing hammers? room temperature? is it a hot summer day or a cold winter day?). The tipping point seems to be the glass transition temperature (Tg) of wool which is around 60 deg C (140 deg F); above this temperature wool fibers begin to change in ways that will adversely affect the resiliency of the finished hammer. During this study it occurred to me that what happened to the felt up on the shoulders might not matter all that much and what happened up there did not necessarily have to happen to the felt down around the striking area of the hammers. To test my idea I made a bottom caul that I could cool independently of what was happening to the side cauls. By circulating cold water through tubing imbedded in the bottom caul I was able to lower the temperature of the bottom caul-that part of the caul that surrounds the striking area of the hammer down to approximately its widest point on the shoulders-to around 50 deg C (about 120 to 125 deg F) regardless of the temperatures of the side cauls. This was well below the target temperature. And it worked beautifully; production speed was unaffected and the hammers became much more resilient. Unfortunately the company I worked for at the time was completely uninterested in pursuing the technology and the project was dropped. Since then I have described the process to several hammer makers (including, a few years back, Norbert Abel) but, as far as I can tell, the words "cold press" still strike fear in hearts of the production hammer maker. More recently I have been able to design changes to the hammer presses at Young Chang so that now the temperatures of the bottom cauls can all be controlled independently of the temperatures of the side cauls. The resulting hammers are significantly easier to match to their intended scales and require much less voicing to adapt them to individual models. And there has been absolutely no increase in production time; the press cycle remains exactly the same as it had been before the press modifications. It never ceases to amaze me that technicians and manufacturers alike will accept rock-hard hammers that require arm-numbing amounts of needling and/or other heroic voicing techniques to make them even marginally acceptable on some chosen piano and then, when they have finally been needled, pounded, lacquered or whatevered into shape, still manage to regard them as good hammers. To me a "good" hammer is one that I can take out of the box and install on the piano and have the thing sound the way it is supposed to sound without all that effort spent to destroy them first. There are so many ways to control the hammer making process that, with just a bit of intelligent trial and error, it should be possible-no, dammit, it is possible!- to make a hammer to suit any piano and any desired piano voice with only minimal voicing required. I regard all voicing techniques as destructive by their very nature. Shouldn't we be looking for hammers that require as little destruction as possible? ddf Delwin D Fandrich Piano Design & Fabrication 620 South Tower Avenue Centralia, Washington 98531 USA del at fandrichpiano.com ddfandrich at gmail.com Phone 360.736.7563 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100929/cd330f2d/attachment.htm>
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