Hello all, I've read this dicussion with interest, and I compare the way you get to those things and the way our action maker approach these problems. Apparently there are different kind of touch that are driven primarly by the distance where the hammer is glued on the shank, be it 125 mm or 130 mm (or even more as seen on some "power flower" actions, that barely work with 11.5 dip) Then the distance between the hammer center (at strike level) and whippen center is fixed , depending of the hammer gluing (if one use standard parts). That gives yet a first key ratio as there is some standard mesure from whippen center to pilot attack point (highest half of the magic line) Then we have a height where the strings are at strike point. And, we need an action that will drive the hammer around 47 mm for a10 mm stroke The distances from lever center to the pilot attack point is more or less fixed depending of the association of parts, essentially to get there on the magic line at half stroke. Hence a whippen, heel choice to get to that standard , While attaining a wanted key ratio that is said to produce the wanted hammer move for 10 mm dip. The vertical spread remain fixed , with some possible declination depending of the kind of touch wanted. A look at this method show us clearly the limitations we encounter, and there are a lot (not speaking of hammer tallness that is also a limit) No mention of weight or BW in this approach, I'll bet that if a BW rasearch is to be made, on may as well check for distance ratio AND for magic line positionning (by computing, not with a thread) The shape of the pilots and whippen saddle does not allow for much variations if we want to avoid undue friction and action inefficiency a full dip because of misplacement. After having seen a captan move made without change of whippen heel placement or height (the wooden edge of the whippen heel was cut to give cleareance for the capstan, that is then acting more or less on the edge of the whippen felt, and not even using the underfelt shock adbsorbing propreties (and that have worn very fast as well) I have lost a lot of interest in David's solutions when it comes to a pianistic touch. (the sharps where asking for way too much dip , yes they had the wanted BW , same as the white) As I try to "keep the baby while throwing out the bath's water" I 'll admit it was a cheap job, for some reason (budget, probably) but this experience showed me that a capstan move is not a so simple thing, even if one is always involved when installing a new action. Weight formulas are certainly useful but we are in a geometrical word with some limits, and as we are unable to compute the action moves in degrees actually (the usual piano technician is not anyway) having tables of reference to use with the usual action part dimensions is very certainly unavoideable (again, if one want to keep good playeability). The reasearch about the shape of the pilot against the shape of the heel have been made yet, and the goal is always to have a capstn rise of a certain dimension, while minimizing friction, or allowing a little more at the end to favour more acceleration at the end of the stroke. I still doubt thes aspects are covered by the balance weight approach, as I doubt the balance weigh is to be even in every kind of action. I have now an interest in developping some tables for myself, these are at first sight produced with relatively simple trigonometric rules, as the initial data is limited (but again, with some standard declination one can use as reference) Using weights to compute ratio is also using a result of added inconsistencies added together, so it is well understandeable that the results may be a little off from the intention in some cases. But having a 2 sides approach may say us if our geometry change lead us to an acceptable or a wanted weight (while keeping action standards, hence no more than 10mm and a smile of dip) Best regards to all. If some are involved in the same kind of table project I like to exchange with them. I forget, we have a last goal which is the alignment of the jack with the roller core, this as well is limiting us, as the spread may not vary so much. This seem to me like the main reason why some actions are slow, or spongy, the installing technician having no other possibility than to cheat on the spread, getting out of the magic line, because something went bad before during selection of parts, design or production. Best to all my friends, I have no much time to read nor write in fact those days. I Hope to be back later. Dont want to make political comments on that list, but the rest of the world is relatively anxious about you, those days, seem to me. Isaac OLEG -----Message d'origine----- De : caut-bounces@ptg.org [mailto:caut-bounces@ptg.org]De la part de Chris Solliday Envoyé : samedi 23 octobre 2004 03:19 À : College and University Technicians Objet : Re: [CAUT] Moving capstans well actually the process is usually done the other way around. I realize I stuck my foot in my mouth (again) and oversimplified. Ric, Ed, and David have given you good advice. And at the risk of beating a subject that you have already laid to rest... the real answer to your original question is there isn't one but what i hope that you are aware of is that in this process we know what ratio is, we know what strike weight is, we can know the front weight, and we have an intended balance weight that we are trying to get and so we could find for KR but it is alot simpler to float the boat (capstan). Afterall who is using other than a 17mm knuckle? and why would you? And the leaway here is very small, ratio is between 5.3 and 5.7 on good actions, bw 35-45 and if you can't get enough down with the capstan there is always the balance rail punching or shim trick further changing KR. Nick G's program is useful fun but ballpark. I could be more specific if I had been able to see the chart but it has been removed and wasn't readable at first. If you're going to do this kind of work I hope you will consider becoming a licensed Stanwood installer. And that goes for you other guys too, Ric excepted and accepted. Chris ----- Original Message ----- From: "Alan McCoy" <amccoy@mail.ewu.edu> To: <caut@ptg.org> Sent: Tuesday, October 19, 2004 5:58 PM Subject: Re: [CAUT] Moving capstans > Hi Chris, > > I know the formula for R, etc. I could also just physically move a capstan > and recalculate. The question though is how to predict the change in BW > resulting from moving a capstan or knuckle, before actually moving it (as > per the analysis sheet). > > Alan > > > > From: Chris Solliday <solliday@ptd.net> > > Reply-To: "College and University Technicians <caut@ptg.org>" <caut@ptg.org> > > Date: Tue, 19 Oct 2004 16:43:31 -0400 > > To: "College and University Technicians <caut@ptg.org>" <caut@ptg.org> > > Subject: Re: [CAUT] Moving capstans > > > > SR= BW+FW-(KRxWW) divided by SW the rest is simple math. > > ----- Original Message ----- > > From: "Alan McCoy" <amccoy@mail.ewu.edu> > > To: "CAUTlist" <caut@ptg.org> > > Sent: Tuesday, October 19, 2004 4:28 PM > > Subject: [CAUT] Moving capstans > > > > > >> Hi Folks, > >> > >> I'd like to pick some of your brains about a problem action. I thought it > >> might help the discussion to include my spreadsheet, but the list > >> administrator thought it better to separate the attachment. If you want > > to, > >> please go to http://www.ptg.org:1406/files/20041019125312.xls for the > >> worksheet. > >> > >> Is there some way to calculate how much BW will change when moving either > >> the knuckle or the capstan? Or does anyone have enough experience/data for > > a > >> rule of thumb for this calculation? > >> > >> Comments? > >> > >> Thanks. > >> > >> > >> -- Alan McCoy, RPT > >> Piano Technician > >> > >> Eastern Washington University > >> 119 Music Bldg > >> Cheney, WA 99004 > >> > >> (509) 359-4627 > >> amccoy@mail.ewu.edu > >> > >> > >> > >> > >> _______________________________________________ > >> caut list info: https://www.moypiano.com/resources/#archives > >> > >> > > > > > > _______________________________________________ > > caut list info: https://www.moypiano.com/resources/#archives > > > _______________________________________________ > caut list info: https://www.moypiano.com/resources/#archives > > _______________________________________________ caut list info: https://www.moypiano.com/resources/#archives
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