<!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 6.00.2900.3059" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT face=Arial size=2>> Now I wonder. Why all the extraordinary trouble to mirror <BR>> polish the back sides of chisels and plane blades dead flat? </FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2><FONT size=3>I think only my trouble. I have been polishing the back side of my chisels and plane blades on the leather wheel of my Tormek. I suspect even someone with good blade sharpening skills would have a tough time making a blade back dead flat on a wheel. When someone with limited skills (or lack thereof), you start putting a small bevel on the backside.</FONT></FONT></DIV> <DIV><FONT face=Arial size=2><FONT size=3></FONT></FONT> </DIV> <DIV><FONT face=Arial size=2><FONT size=3>Whomever suggested that I keep my Shapton stones, I think might have a good suggestion for me - maybe I'll try working the backsides of my blades on the stones. The only thing I didn't like about the stones is that you need to have the skill to hold a blade at the correct angle to sharpen the bevel - I have never been successful at that.</FONT></DIV> <DIV><BR>> The control and precision required to fit traditional Japanese <BR>> joinery is far beyond that needed to notch a bridge, or much <BR>> of anything else we do to pianos. A notch scoop with only one <BR>> nominally critical edge is somewhat different from maintaining <BR>> straight lines and tight fits on three axes in a complicated <BR>> joint in finish carpentry. And why would a plane blade need a <BR>> hollow behind the edge under ANY conditions? As friction <BR>> relief and fine depth control with a freehand chisel used in <BR>> microfitting joints, yes. In a plane blade that is wedged in a <BR>> block that handles the cut depth, friction, and presentation <BR>> angle, what's the hollow for?</DIV> <DIV> </DIV> <DIV><FONT size=3>Are you referring to a hollow on the backside of the blade or on the bevel? I did ask about a hollow on the back side of a Japanese chisel, but my plane blades do not have any hollow at all. On the 1/2-inch-thick Mazzaglia chisels, grinding the entire beveled surface (on my 1" chisel, you have about a one-inch-square bevel surface) is extremely time consuming. If you put a slight hollow on the bevel, you only have to grind on a thin swath at the edge and the other end - makes sharpening go much faster.</FONT></DIV> <DIV><FONT size=3></FONT> </DIV> <DIV><FONT size=3>Is that what you were addressing?</FONT></DIV> <DIV><BR> <BR>> Virtually all my sharpening is done with a coarse 6" DMT <BR>> Diasharp "stone" and a steel or ceramic rod if necessary, or a <BR>> worn out fine grit EZE-LAP (I think it is). Major chisel or <BR>> plane blade reshaping, in the rare instance of need, is done <BR>> carefully on the bench grinder with a coarse wheel. My <BR>> notching chisel has an intentionally slightly rounded back <BR>> edge (maybe 1mm), because I can steer it better through the <BR>> scoop than a flat backed blade.<BR>> <BR>> There is nothing magic about Japanese chisels other than the <BR>> extremely hard steel that the laminated construction allows at <BR>> the edge (which is admittedly terrific). The presumed need for <BR>> a mirror finish on an absolutely flat back, I don't see as <BR>> valid for the uses we make of them. If someone made laminated <BR>> long bladed paring chisels with flat backs, I'd likely upgrade <BR>> my chisel collection. Does anyone?<BR>> <BR>> Ron N<BR>></FONT></DIV> <DIV><FONT face=Arial size=2>----- Original Message -----  <BR>>> Something that has been troubling me ever since I bought my Japanese <BR>>> chisel: Starting just a few millimeters back from the sharpened edge, <BR>>> the entire backside has a hollow ground out. Why? Is that to make <BR>>> flattening the backside easier? After many sharpenings, the edge of my <BR>>> chisel is getting very close to the beginning of that hollow. Of course, <BR>>> as soon as the edge gets right up to the hollow, the chisel dies. Is <BR>>> this just a feature to sell more chisels?<BR>>>  <BR>>> Terry Farrell</FONT></DIV></BODY></HTML>