Bravo! well said. Fini ----- Original Message ----- From: "John Delacour" <JD at Pianomaker.co.uk> To: <pianotech at ptg.org> Sent: Monday, February 08, 2010 6:41 PM Subject: Re: [pianotech] Hammer strike line > > Before the discussion goes completely off-topic I'll give my take on > the question of the strike line. > > My definition of the strike line is the first (straight) line that is > made on the drawing board in the designing of a piano and is the line > that crosses the strings at the point where the hammers are > _intended_ to strike the string, with the hammer-heads at a right > angle to the strings. > > From this line, the line of the string to the top bridge (agraffe > etc) and the line to the first bridge pin are drawn in a certain > proportion one to the other, this proportion having been determined > by the piano maker, through his own experience and that of his > predecessors and masters, to be the very best proportion for the > piano in question and similar pianos. > > In a piano of reputable manufacture it is unlikely that the choice of > these proportions is anything but the best, and no matter what the > condition of the soundboard is, it is unlikely that the tone of the > piano can be improved by striking the string at any other proportion > of its length than that set by the maker. > > A bird's eye view of the strike line will show it as straight. Gross > errors in the placement of the agraffes and the bridges will > frustrate the designer's plans. Lesser errors will make very little > difference except in the extreme treble. > > A view of the strike line from the front (ie. a line joining the > points that represent the strike height at the strike line) will > occasionally be straight but more often than not it will have steps > (at the breaks), slopes and curves. In addition to this, > particularly on pianos with agraffes all the way up, the angle of the > strings to the horizontal (going at an upward slope to the bridge) > will increase in the top section towards the top. This also needs to > be taken into account. > > If the hammers are correctly bored as regards bore length and bore > angle, by taking into account the above factors and calculating the > bore given a straight hammer rail at a constant height above the > key-bottom (and this must be most carefully verified and adjusted as > necessary having regard to the total geometry of the action, which is > a whole nother story) then each hammer will strike its string at a > right angle and at the strike line, and the best possible performance > will be had from the instrument. > > If I buy standard bore hammers for a Steinway my chances of getting > things wrong are roughly 100%. I worked on a very fine 1970s Hamburg > model B a couple of months ago that had the original hammers and > these had been certainly been refaced once or twice but this would > have accounted for the removal of say 3mm from the nose of the hammer > at the maximum. It was obviously a great piano but performers were > complaining of weaknesses. I had Abel make me a set of raw hammers > and bored them according to my calculations from the careful > measurements I had taken. The bore of my hammers differed from the > originals by up to 8 millimetres! and, since they were, for the first > time ever, hitting the strings in the right place at the right angle, > the piano has a purity and power that it never had before. > > One of my current jobs is a 1927 Model O. If I had ordered standard > bore hammers with a bore length of 45 mm, again I would be wrong. At > places in the scale I need a bore length of 49 mm because the string > heights are not what they should be for the given action and 45mm > hammers. > > The alternative to doing things properly is to take no measurements, > make no calculations, buy standard hammers and make the best of a bad > job by shifting things backwards and forwards until they sound OK. > > JD > > > > > > > -- > ______________________________________________________________________ > Delacour Pianos * Silo * Deverel Farm * Milborne St. Andrew > Dorset DT11 0HX * England > Phone: +44 1202 731 031 > Mobile: +44 7801 310 689 > ______________________________________________________________________ >
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