That spark test is interesting... I'm going to go test my chisels now! -John Parham Hickory, NC > -------- Original Message -------- > Subject: [pianotech] Of Chisels > From: Les Koltvedt <t4348lk at yahoo.com> > Date: Sun, October 10, 2010 7:51 am > To: pianotech at ptg.org > > > The kind of sparks given off when grinding will give you a hint at to what kind > of steel your dealing with. Here's one site I found describing the different > sparks. http://www.capeforge.com/Spark%20testing.html > > I've always heard that a sharp tool is a safe tool. There's no better feeling > then pushing a chisel that you've sharpened through some wood and it slides > like butter. > > Les > > Date: Sat, 09 Oct 2010 09:10:22 -0700 > From: <johnparham at piano88.com> > To: pianotech at ptg.org > Subject: Re: [pianotech] Of Chisels > Message-ID: > > <20101009091022.f1fd8b108a58a93f763c4cd7f53850a9.fe2cdc6be6.wbe at email03.secureserver.net> > > > Content-Type: text/plain; charset="utf-8" > > In following this post on sharpening chisels, I ran across two > interesting facts on sharpening kitchen knives that may apply here as > well: > > 1. If you see sparks during the sharpening process, too much heat is > building up. The result is you loose the temper on the blade. > > 2. The evolution from cast iron (hard, but brittle and prone to rust), > to carbon steel (harder, but still brittle and still prone to rust), to > stainless steel (hard, resilient and much more rust-resistant) has led > to the development of a new kind of steel called ultra-high carbon > steel. This steel contains a much higher concentration of carbon, > making it even more resilient. More resilience means the very sharp > metal edges are less prone to breaking off. These edges tend to last > 5-10 times longer than traditional stainless steel edges, so the blade > stays sharper longer. > > I wonder if some of these Japanese tools use this kind of metal? > > -John Parham > Hickory, NC
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