[pianotech] Of Chisels

[johnparham at piano88.com]

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

> -------- Original Message --------
> Subject: Re: [pianotech] Of Chisels
> From: Ron Nossaman <rnossaman at cox.net>
> Date: Sat, October 09, 2010 11:20 am
> To: pianotech at ptg.org
> 
> 
> On 10/9/2010 4:11 AM, David Boyce wrote:
> >   Speak to me of chisels, folks.
> >
> > What makes them able to take a good edge or not?
> 
> Hardness, angle, and sharpening method. Straight razors are made of very 
> hard fine grained steel, hollow ground to a very shallow angle. This 
> gives maximum sharpness at the expense of durability. Mortising chisels, 
> needing a considerably more durable edge, are ground and sharpened at a 
> much steeper angle. Paring chisels are in between the extremes, 
> depending on what you're using them for.
> 
> Through the years, I've picked up a selection of old socket handled 
> chisels of various makes. Assuming that some troglodyte dipstick hasn't 
> hammered the handle-less socket into the mushroom of death, I like these 
> chisels. Handles are easy enough to make and fit, since they're usually 
> without. They're typically good steel, with long blades. Laminated 
> Japanese chisels are terrific, but I really do like the long bladed 
> paring chisels for most things. I even have an old 45mmx220mm blade, 
> socket handled slick that I find useful more often than you might think.
> 
> Start with decent quality chisels, and spend some time sharpening them. 
> You can buy a power sharpening system, hundreds of dollars in Japanese 
> water stones, with the expense and upkeep necessary to both, or follow 
> Sham Wow (the path of the Billy Bob) and freehand bevel on a bench 
> grinder (careful with heat), and sharpen on a diamond grit "stone".
> Ron N