<html> <body> Hi Ric,               3mm is outside of the box  for most manufacturers, for spec regulation.    A good concert reg would be 2mm let off and 1mm drop if all action parts are sound.  Good hammer tailing and rep springs must be regulated to a professional level. I also look for 1/4" checking on a concert reg.  Friction in the rep slot is also critical. Now I feel better having stirred the pot <G> Regards Roger <blockquote type=cite class=cite cite="">Over to Jim Hudsons article tho... Dont you think a whole 3 mm letoff is a bit overkill on the safe side ?  Where do you generally like letoff and drop yourself, and why ? Interesting to find so much variance in this seemingly simple point. Cheers RicB James Ellis wrote: <blockquote type=cite class=cite cite="">This is one I can't resist, so I am going to jump in here with my "two cents worth" (No, it's not about tuning). "PRACTICAL CONCERT WORK" by Jim Hudson, June 2004: What no one seems to have noticed is the word "Practical" in the title. That sets the tone for the whole article, but some readers did not seem to hear it.  Fred Sturm says he prefers to set let-off at 1/32 inch.  Well, I don't.  If I set it like that, I'd be in trouble for sure.  That's right at the very edge of blocking, and even if it does not block outright, it does not produce a clean let-off, and that results in occasional bizarre sounds when the hammer does not completely clear the very first-half cycle of the strings vibration.  David Love says setting let-off like this is "dangerous", and I agree.  Otto Keyes says "consistency" is what one should strive for, and I agree with that too.  But if you regulate to a "gnat's eyelash", Bill Garlick has said you better stick around for the concert. True, but that might be too late. In all this nit-picking with Jim Hudson's article, did no one mention drop regulation?  If you want consistent response for playing very soft passages, you had better pay close attention to that too, as well as to consistency in the regulation of the repetition springs, and everything else. "MAGNETIC ASSIST FOR GRAND PIANO ACTIONS", by Richard Brekne, June 2004: With all this interest in nit-picking Jim Hudson's article, am I the only one who has taken a special interest in Brekne's article?  This is really neat!  It is innovative.  It is clever.  There are other magnetic touch systems around, but this one has something clever that the others don't. One of the first questions that popped into my head was the non-linear decrease in magnetic repulsion as the two tiny magnets move farther apart as the key moves.  Richard takes care of that by suggesting a second pair of magnets behind the capstan, which would be attracting.  Thus, the non-linear repulsion of the first pair would be compensated by the opposing non-linear attraction of the second pair.  Very clever indeed!!  In other words, the combined effects would apply a measured force tending to rotate the front of the key downward and the wippen upward around a pivot at the point where the capstan touches the wippen cushion.  Since the capstan never leaves the wippen coushion, the action ratio is not changed.  All that happens is that the need for lead in the fronts of the keys, and the moment of inertia is reduced, without the use of springs.  The thing to watch out for here will be that the spacing of the magnets will need to be regulated as the capstan depresses farther into the wippen cushion over time.  This, in my opinion, is very clever and very innovative, and I for one would like to see how it all plays out in the end.  Congratulations, Richard! Sincerely, Jim Ellis _______________________________________________ caut list info: <a href="https://www.moypiano.com/resources/#archives" eudora="autourl">https://www.moypiano.com/resources/#archives</a>   </blockquote> _______________________________________________ caut list info: <a href="https://www.moypiano.com/resources/#archives" eudora="autourl">https://www.moypiano.com/resources/#archives</a></blockquote></body> </html>