[pianotech] Of Chisels

[johnparham at piano88.com]

Thanks David... good addition to this thread.

-John Parham


> -------- Original Message --------
> Subject: Re: [pianotech] Of Chisels
> From: "David Love" <davidlovepianos at comcast.net>
> Date: Sat, October 09, 2010 1:49 pm
> To: <pianotech at ptg.org>
> 
> 
> Sparks don't necessarily mean that the chisel is getting too hot but it can if you aren't careful.  A bench grinder and fine and extra fine diamond stone (or wet stones) along with some polishing compound are all you really need to sharpen a chisel and it shouldn't take that long, five minutes or less.  It's more a matter of knowing what to do than a difficult skill to acquire.  Set the desired angle on the grinder platform (usually 25 degrees) and then very lightly create a hollow grind that doesn't quite reach to the tip of the chisel (by a couple of mm's unless the chisel is damaged).  If you hold the chisel against the grinding wheel with a couple of fingers placed near the edge you'll be able to feel if there's any heat building up--it'll will burn your fingers.  Go slowly with a light touch and check your work frequently.  That gives the chisel a two point resting position when set on the stone that you can very easily tell when it's resting flat and in which you then sharpen the leading edge.  Hold the blade flat on the stone with two fingers placed near the tip of the chisel to keep it securely held down on either side of the hollow bevel, handle facing away from you and use a push stroke to sharpen the edge.  It doesn't take that many strokes with a very thin leading edge.  Go to the extra fine stone and do the same thing alternating between light pressure on the flat back of the chisel and the leading edge (you're turning the chisel back and forth).  Then spread a small amount of car polishing compound on a flat piece of plywood, mdf, old pinblock material, whatever and hone the edge (both sides) to clean up any burrs that are left over.  You should be able to push the chisel into the edge of a piece of paper and have it slice cleanly when you are done.  Or you can spend $500 on a Tormek system.   
> 
> David Love
> www.davidlovepianos.com
> 
> -----Original Message-----
> From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of johnparham at piano88.com
> Sent: Saturday, October 09, 2010 9:10 AM
> To: pianotech at ptg.org
> Subject: Re: [pianotech] Of Chisels
> 
> 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