On 8/11/2010 8:44 PM, William Truitt wrote: > > What should I zero the gauge to? There seems little in a piano that > is flat and level to serve as a meaningful reference. I want a proper > reference point to zero to, so that the values will accurately reflect > the angle of the string. What are others using as their reference? > Hi Will, I use it mostly for measuring the composite bearing angle (as opposed to component, ie front then and back angles separately). For a composite measurement, you don't have to zero it out on any thing actually. I generally just place it on a speaking length near the bridge, zero it to that speaking length. The speaking length of that string has now become the reference to determine the composite angle for that string, and only that string. It's not a reference for the entire piano, only for that one string. Move the gauge to the back scale and read the angle, noting which way the little arrow is pointing to make sure the new reading is telling you there is a positive or negative angle. After I get going, I really don't bother zeroing it at all, rather just note the difference between the speaking length reading and the backscale reading, ie speaking length reads .5 (up arrow), .9(up arrow)= .4 deg positive bearing. Then move on to the next string and do the same thing without zeroing at all. The first measurement for each string becomes the reference for that string, and that string alone. The thing to watch out for is the up/down arrow. If you have readings like: -speaking length (up arrow), backscale (up arrow, higher reading that speaking) the bearing is positive -speaking length (up arrow), backscale (up arrow, lower reading that speaking) the bearing is negative -speaking length (down arrow), backscale (up arrow, higher reading that speaking) the bearing is positive -speaking length (down arrow), backscale (down arrow, closer to zero than speaking) the bearing is positive -speaking length (down arrow), backscale (down arrow, further from zero than speaking) the bearing is negative that sound like a lot of thinking, but its not, once you get the hang of it. Watch out for the swage on the bass string, it will give a false speaking length reading. The backscale, for the front pin to the hitch termination, is not a straight line as you noted, however the amount of that that small deviation, given the general noise in belly measuring is in my opinion not worth fussing about. For example: Given a speaking length of 17.5", a backscale 6.3", front pin .125"height above theoretical straight line between agraffe to hitch, the angle formed would be 178.5 deg(1.5 deg). If I were to take into consideration a .75" bridge top and assume that it is parallel to the theoretical straight agraffe to hitch string line, the composite angle becomes 178.38 deg(1.62 deg), a difference of .12 degrees. Given that the wixey or beal both have an accuracy of +/- .2 deg the .12 deg inaccuracy is within the noise of what is measurable here. Also note that although the wixey has a resolution on .1 deg and the beal a resolution of .01 deg...the difference between the two is basically marketing, because they both have an accuracy of only .2 deg. I think others may use the gauge for component measuring, but I don't personally see what component measurements give you that is more practically useful than a composite angle...however, I'm sure others will chime in. Jim I -- Jim Ialeggio grandpianosolutions.com 978- 425-9026 Shirley, MA -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100811/6c57bfc3/attachment-0001.htm> -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: image/gif Size: 69751 bytes Desc: not available URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100811/6c57bfc3/attachment-0001.gif>
This PTG archive page provided courtesy of Moy Piano Service, LLC