Isaac wrote: >High speed analysis should certainly be interesting for that matter, >but a simple time spectra analysis can yet show us things. The >device used for the test blows at the PTG seem a good one for that >kind of test. I'll add something to our roster of experiments to target this effect and see if we can get to the bottom of it. >I am persuaded also that the stiffness of the wire being stiffer >with a lower backchecks the checking stroke is firmer. and Andre wrote: >According to him (Tsuji-san), there should be a space of 2 mm after >drop between hammer tail and back check. There's still quite a few parameters that can be changed while maintaining this 2mm space, e.g.: - (as Ed suggested) relative angle of backcheck and hammer tail surfaces on checking (tall angled check vs shorter more vertical check = same height of top) - stiffness of the backcheck wire and leather etc. - strength of the rep spring (how much does the hammer tail impinge into the 2mm space during its journey to "caught" position, at which the 2mm space is measured) If there *is something special about the 2mm spacing per se, then the effect must presumably be indepedent of these other factors. So, when faced with a non-kosher arrangement, what process exactly is done to adjust the backcheck position? Andre again: >I got out my Japanese tool to change the height of the back checks >and I started twisting and turning the back checks to the desired >height. This sounds like: a simple change in height only. Is it certain that that special tool doesn't affect anything else, even accidentally, like the angle of the wire? What is the effect of screwing the backcheck, on the final resting checked height of the hammer, as compared to the backchecking position of the original "incorrect" arrangement? Sounds disrespectful talking about 2mm thingies, compared to the devastation we've been hearing about from our FL friends. Stephen -- Dr Stephen Birkett Associate Professor Department of Systems Design Engineering University of Waterloo Waterloo, Ontario Canada N2L 3G1 E3 Room 3158 tel: 519-888-4567 Ext. 3792 fax: 519-746-4791 PianoTech Lab Room E3-3160 Ext. 7115 mailto: sbirkett[at]real.uwaterloo.ca http://real.uwaterloo.ca/~sbirkett
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