<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: Lowell Component Downbearing Gauge</title></head><body> <div>At 9:26 pm +0000 6/5/07, jimialeggio5@comcast.net wrote:</div> <div><br></div> <blockquote type="cite" cite>So anyway, this is an official not quite baked idea...but I don't think its half-bake, so-to-say.<br> </blockquote> <blockquote type="cite" cite>I'd be interested in followups of anyone foolong around with the idea.</blockquote> <div><br></div> <div>The Wixey gauge is indeed very interesting and handy,  Thank you for posting the information.  I see that I can buy one on new on eBay here in England for Ł25 postage free and will almost certainly do so.</div> <div><br></div> <div>HOWEVER this gauge suffers from one obvious shortcoming and that is its resolution to only 0.1 degrees, which might not sound much when you say it quickly, but in practice is equivalent to a card's thickness (roughly 9 thou or 0.22mm) at the string rest given a back-length of 5 inches (127 mm.), and a very significant percentage of the actual range of angular deflection applied in practice.  As regards downbearing, an angular deflection of 0.1 degree represents about 70 pounds-force at the bridges when applied throughout the typical grand piano.</div> <div><br></div> <div>From what I can see of Dale's device and gauge, even if his gauge stepped (go no-go), as it seems to be, in steps of 5 thou, he is still able to measure the angle with half the tolerance of the Wixey gauge, ie. to within 3' or 0.05 degrees.  With a continuous wedge gauge it is possible to achieve even better accuracy.</div> <div><br></div> <div>At 9:05 am -0400 4/5/07, Dale Erwin wrote:</div> <div><br></div> <blockquote type="cite" cite>On a 5 inch string segment yielding a gap of .065 thous (as measured with the gauge in the picture) reveals that there is about 3/4 of a degree of residual net bearing.  Now this is a new board set up at 1 1/2 degrees. So I've squashed the board 3/4 of a degree.</blockquote> <div><br></div> <div>In fact in this instance Dale's measurement could hardly be more accurate since</div> <div><br></div> <div>    sine(3/4) x 5" = 0.0654"</div> <div><br></div> <div>but even supposing Dale is using a go-no-go gauge with 5 thou steps and went to the 70 thou step rather than the 65 thou, the calculated angle would be only about 0.05 degrees different.  I've photoshopped Dales picture to make it quite clear where the gauge rests, on the speaking length in front of the pins.</div> <div><br></div> <div align="center"><img src="cid:p06240814c26485e3258d@[10.0.0.1].1.0"></div> <div><br></div> <div>That said, I'm sure Dale will agree that although this method is quite accurate for measuring and demonstrating the angle after the event, it is not the perfect method for setting up the angles before the piano is strung.</div> <div><br></div> <div>JD</div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> </body> </html>