<font color='navy' size='2' face='Comic Sans MS, sans-serif'><b><font size="2" face="Courier New, Courier, mono">The </font><font size="2" face="Courier New, Courier, mono">action ratio gauge</font><font size="2" face="Courier New, Courier, mono"> I make for the trade has a pre</font><font size="2" face="Comic Sans MS, sans-serif">-</font><font size="2" face="Courier New, Courier, mono">printed scale on the back for ease of reference. See attachment.</font></b> <div><b><font size="2" face="Courier New, Courier, mono">6 mm isn't just for ease of reference.</font><font size="2" face="Courier New, Courier, mono">It cover a wide swath of the keystroke and </font><font size="2" face="Comic Sans MS, sans-serif">s</font><font size="2" face="Courier New, Courier, mono">omewhere between 7 & 8 mm of key travel the l.o. button comes into play. </font></b></div> <div><font size="2"><font face="Courier New, Courier, mono"><b><br> </b></font></font></div> <div><font size="2"><b><font face="Comic Sans MS, sans-serif"> </font><font face="Courier New, Courier, mono">David. Another thing to try is remove the drop screw and turn the L.O. button all the way up. Now take a 10 mm sample or a full keydip/travels worth of hammer movement and see if it changes your outcome.</font></b><br> <br> </font> <div style="color: navy; font-family: 'Comic Sans MS', sans-serif; clear: both;"><font color="royalblue"><b><font face="Georgia, Times New Roman, Times, Serif"><font color="black"><font color="mediumblue" face="Comic Sans MS, sans-serif"><font size="2">Dale Erwin R.P.T.</font><br> </font></font></font></b></font></div> <div style="color: black; font-family: arial, helvetica; font-size: 10pt;"> <div id="AOLMsgPart_0_695f6c4b-225f-4197-b89c-9ed2073a7d71" style="margin: 0px;font-family: Tahoma, Verdana, Arial, Sans-Serif;font-size: 12px;color: #000;background-color: #fff;"> <pre style="font-size: 9pt;"><tt> >>A simple block of wood with an extension (mine is a machine screw) that laysacross the keys and that depresses a key exactly 6 mm whereby you then measure the amount of hammer travel and divide that by six to give theaction ratio.<> Not sure why it's 6 mm, tho. Why not 5 mm, which is 1/2 of most key dips << Greetings, I like the 6 mm for its ease of reference. I use a jig like Davids, and I place a needle through some unused part of the hammer felt so that I can measure its rise against a scale as closely as my nearest pair of reading glasses lets me. It it goes up 36, its a 6:1, 30mm and its a 5:1, all points in between are fairly easy to approximate, i.e. 33 mm would be a 5.5:1, If anybody takes the time to be really careful, the ratio can be seen to change between the first 4 mm of key travel, and the last 4 mm. At least, I have. I think it gives a good indication of how to optimally arrange the congruence of the capstan's arc with the whippen's. regards, Ed Foote RPT <a href="http://www.piano-tuners.org/edfoote/well_tempered_piano.html" target="_blank">http://www.piano-tuners.org/edfoote/well_tempered_piano.html</a> </tt></pre> </div>  </div> </div> </font>