<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 5.50.4134.100" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT face=Arial size=2>I gave the technical on hammer boring = at the chapter meeting, (with the back-up of the RPTs at the meeting), and = nobody could explain what the criteria would be for determining hammer bore distance = and rake for optimum performance on an upright. Sure, go by the = original is an easy answer but what if it looks as if somebody who "hadn't a = clue" put those hammers on. I have 3 old uprights here, a 1909 Smith and = Barnes, a 1911 A.B. Cameron, and a 1906 Kohler and Chase. The first two, the = hammers shanks are close to parallel with the string plane, and the rake is = minimal. Or, worded differently, the bore distance is the distance from the = hammer flange center pin to the string plane. Rake is 1 or 2 degrees. = </FONT></DIV> <DIV><FONT face=Arial size=2>The Kohler has much more rake, 5+ = degrees and the shank is at the similar angle to the string plane so the hammer is = square to the string plane when it hits.</FONT></DIV> <DIV><FONT face=Arial size=2>Why?</FONT></DIV> <DIV><FONT face=Arial size=2>Should I be looking at the angle of the = jack to the whippen at the start of lift? The hammer butt/jack angle at let off?</FONT></DIV> <DIV><FONT face=Arial size=2>Or maybe it was something simple, like = the little bit more clearance that could be had by moving the action closer to the strings.</FONT></DIV> <DIV><FONT face=Arial size=2>Anybody?</FONT></DIV> <DIV><FONT face=Arial size=2>Keith = Roberts</FONT></DIV></BODY></HTML>