---------------------- multipart/alternative attachment At 2:16 PM -0800 1/11/02, David Love wrote: >Just to clarify my position on this a bit, I haven't yet encountered an >action where low ratios below 5.5 didn't create regulation compromises that >I found undesirable, and there it was pushing it. Agreed! > I was surprised to hear David S. comment that he achieved 10 mm >dip 44.5 blow >with an action that measured 5.0. If I recall his post correctly, I think he was referring to Hamburg Steinways being regulatable with their typical 5.0:1 hammer/key ratios for their largest piano. >That has given me some pause but doesn't >change my own experience. I have watched a couple of Hamburg techs setting up Ds. Sure they carry a "D" key dip block which measures 9.8 mm, but they actually set the dip at around 10.5 mm from what I have observed. I have found 10.25 mm dip to be a practical minimum for such actions with hammer/key ratios as low as 5.0:1. Terry Farrell's recent experiment, where he calculated hammer/key ratios using leverage analysis and weight analysis, yielded typical results. The higher 'actual' ratio occurs to a greater degree for those actions where the lever contacts are further from the lines of centres. The greater the lever contact distance from the line of centres (particularly with regard to the Jack/roller relationship) the greater will be the difference between the actual figures and that calculated by lever lengths. One therefore should be careful to compare figures between pianos by calculating the hammer/key ratio via the same method when drawing conclusions, ie. don't measure one piano via weight calculation and use the results to predict the behaviour of another action by measuring it using the leverage calculation method. Some of you may recall that I previously had experienced some frustration getting our actions made exactly to specification. Well the latest arrival was very accurately made - by Tokiwa. I am presently fitting it to a standard factory keyboard from the leading manufacturer who will be trialing an Overs action very shortly. I was very surprised to find that the balance pin hole locations were drilled 'all over the shop' (some errors exceed 1 mm). This was indeed a surprise since the keyboard was manufactured by one of the world's most respected key board manufacturers (the one who manufactures for the 'top end' makers). Since we drill our capstan lines using a mill/drill with a jig which indexes from the balance pin holes, the capstan line on this occasion isn't. Consequently this Overs test action will require all sorts of variations in the key dip to achieve a uniform after touch (which I am less than pleased about). Unfortunately, I have to export the action and key board next Wednesday so there is no time to rectify the ordinary key board workmanship. Ron O. -- _______________________ OVERS PIANOS - SYDNEY Grand Piano Manufacturers Web: http://overspianos.com.au mailto:info@overspianos.com.au _______________________ ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/88/e5/61/6f/attachment.htm ---------------------- multipart/alternative attachment--
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