Ok Dale I'll take the bait...
At least from the keyboard design perspective, the point at the front of the key and below the key covering is used as THE reference point for establishing (and measuring) both key height and dip. Before there is an action on which even to set after touch, it exists on paper as a design. Certain decisions are made as being immutable such as entrance and string height, the selected topstack parts and their center's x & y coordinates, the strike point, the hammer bore and regulating dimensions. Then the parts are set into the half stroke position and that line is extended to establish the eventual front and rear lever arm of the keystick. The key is laid into the design at its rest position and the keyheight and the back rail cloth dimension (or more importantly, the rear key height) are already determined. The key is then rotated into the half position and the location of the balance point, balance rail height and capstan location are determined. Many of these specs are not "gods" unto themselves but only existed at the beginning; and if they got it right in the first place, they can be maintained. Anyway, never assume, do the math.
Now in the real world, we have migrating string heights and other variables that wander from our design specs of four decimal places. Here is where the artistry takes over and we can use every perspective and trick we've ever learned simultaneously. I use the same method as David Love, but I also certainly concur with Rick Breckne and Andre's perspective.
Great thread BTW and I wish I could chime in more but with three hungry and screaming youngens and trying to eek out a living, I'm afraid I can't offer much more for now, but know that I'm lurking. :)
Jude Reveley, RPT
Absolute Piano Restoration, LLC
Lowell, Massachusetts
(978) 323-4545
----- Original Message -----
From: erwinspiano at aol.com
To: pianotech at ptg.org
Sent: Saturday, February 28, 2009 1:37 PM
Subject: Re: [pianotech] Fwd: Erwins key dip gauge
Ok, Since nobody solved the mystery question of where or how does one measure the dip/key travel...
At red School house in 1976 we were instructed to measure the total key dip/travel from the under side of the key cover with a metric ruler.. It's a great visual reference point. Later, I discovered for myself that I didn't like 10mm & preferred 10.5 instead
When using my gauge the measurement of .390 which again, is measured at slightly in front of the pin will yield a ruler reading result at the front of the key of 10.5mm. But I no longer have to get bi-focal's & headlamps to try to read the little tiny numbers on the ruler. It's a gauge that is a magnifying glass not a microscope but its pretty dang close.
Dale
Hi Dale...
I thought I answered this already... perhaps I misunderstand exactly what your question is. After bedding and leveling, I use a standard 10 mm key dip block to do a rough setting of key dip, then do as good a regulation as I can, then refine key dip to achieve as even an aftertouch as I can. I like to double check letoff-drop and jack/rep-arm orientation as I go along in this aftertouch refinement. Sometimes a small adjustment in one of those is whats called for instead of a slight change in the dip.
I dont actually "measure" per se as I think I understand your query at all. Perhaps if you described what YOU do I might better understand what you are getting at.
Cheers
RicB
Ric
Ok, Good points. I was waiting for the answer but...ok... where &
How do YOU measure key dip?
Hmm
Dale
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