Getting into this late but small piano right? Short keys? You can balance this action easily to a BW of 37 by just creating a smooth SW curve and manipulating lead weights without getting too much lead in the keys. I would guess that the hammers are bored too short or worn--check again. The SWs indicate that the hammers are quite light and the tone may be better that way on this piano. 41mm blow is a bit short but with 10.5 key dip you can't increase the blow any more without creating too much dip--though 11 mm is not totally unheard of. If you raise the sharps to 12.5 mm (1/2") they will not bury in the naturals and won't feel too high. What's the overall plan? If you are replacing hammers you have some choices about reboring, if not, play with the spread a bit and see what you can do in terms of changing the dip/blow balance, otherwise, on this piano power is probably not that much of an issue and redesign costs might be prohibitive. Keep it simple. David Love www.davidlovepianos.com -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Gene Nelson Sent: Friday, March 13, 2009 4:52 PM To: pianotech at ptg.org Subject: Re: [pianotech] high leverage action > Hmmm... I think we'll have to be a bit more specific then that. A 10 gram > strike weight in the top low strike weight zone equates to something > around hammer number 5. A weight of 5 at key 88 is perhaps a quarter zone > higher... that means you have really low hammer weight if this is > reflective. ***** I will probably push the hammers up to number 6. As I said, I have not done any corrective hammer leading yet. Front weights... assuming we are balancing the > same notes you mentioned for hammer weights then you have an action ratio > of 6.2 in the bass ranging to 7.8 in the treble. Kind of wild... but > suffice to say you have a high action ratio... which fits at least your KR > and Knuckle configuration. Without more specifics this is just ball park. > I'd ask for at least 7-8 samples of SW, FW, BW, and KR along with your WW > to get a more accurate picture of your situation... say all C's but I > think its safe to say you have a pretty high action ratio....no matter > which way you look at it. ******My samples were not all C's but they are all naturals, first and last in each section. - here it is: note# SW FW BW KR WW 1 10 30.1 41.5 .55 16.4 25 10 26.7 42.5 .52 16.4 27 9.3 23.8 39.5 .54 16.4 45 8.4 15.5 44 .54 16.4 47 8.7 16.6 42.5 .53 16.4 66 6.8 7.7 42.5 .54 16.4 68 6.5 6.5 41.5 .54 16.4 88 5.0 6.8 36.5 .53 16.4 Note that the WW value is the same because it is the average - the range was from 15.9 to 17.2 > > Why you end up with such a short blow distance and deep key dip to get any > aftertouch is a good question if the above is close to the truth of the > matter. A short bore length would force you to raise the shank closer to > the strings... ie raise the underlever (whippen) which should not require > a deep key dip to get aftertouch. A long one would keep your shank just > off the rest cushion at a shorter blow distance... and perhaps fit the > condition of a high action ratio thats heavy, has keep key dip and short > blow with minimum aftertouch. But if you are certain about bore length > being at String height - hammer shank center height then something is not > quite right with this whole picture.... grin.. or its just so late over > here that I've got things backasswards again.... wouldnt be the first > time. :) ****I am absolutely certain that the bore distances are based on String height - hammer shank center height. > > As far as minimum 44 mm. I think thats about as short a blow as you can > allow for without sacrificing too much power. Usually you find somewhere > between 45 and 49... sometimes 44... sometimes 50.... rarely outside that > because of what implications it has for the rest of action regulation > specs. We have this ideal of about 10 mm key dip, and about 1.5 to 2.5 mm > letoff... which more or less dictates blow for any given amount of > aftertouch. It all adds up usually to somewhere between 44 and 50 for > blow. **** I measured the height of the sharp blocks to get an idea of maximum key dip. Not that I like that much necessarily. Gene > > Cheers > RicB > > >> >/ What are your Hammer Strike weights >> /*****10 in the bass and 5 in the treble - no corrective weighting action >> taken yet. >> >> and key Front Weights ? >> ***** >> 30 in the bass and 6.8 in the treble >> >> Your dip >> >/ and blow say low ratio but your KR and knuckle distance says high. How >> />/ much aftertouch are you getting with things as they are... >> /***** about 1.5mm or slightly less. >> >> how far out >> >/ from under the knuckle does the jack move ? >> /*****Just enough for drop and aftertouch to happen. >> >/ >> />/ 41 mm is on the short end of the stick to be sure. I usually dont >> see />/ under 44 and never allow for less when redoing an action. >> /***** Do you have a reason for maintaining 44mm or greater blow >> distance? >> >> Regards, >> Gene >> >/ >> />/ Cheers >> />/ RicB >> />/ >> />/ >> />/ Hello list, >> />/ Thought that I would seek comments on an action with high >> leverage. >> />/ Key dip is 10.5mm and blow distance is 41mm. >> />/ The touchweights are in the low 50's down and low 30's up. >> />/ Knuckle spread 16.5mm >> />/ Key ratio is 1.81 >> />/ Action spread is 113mm and is adjustable. >> />/ Any more dip will make the sharps about level with the naturals >> when >> />/ depressed. The feel of the samples are acceptable. Seems that 41mm >> />/ blow distance is short - but is it too short? Maybe some loss of >> />/ power? Is there a down side to this action? Any corrective >> />/ suggestions? It is in the sampling - disassembled stage. >> />/ Thanks, >> />/ Gene >> />/ >> />/ >> />/ / >
This PTG archive page provided courtesy of Moy Piano Service, LLC