chisels

[Ron Nossaman]

>  > Now I wonder. Why all the extraordinary trouble to mirror
>  > polish the back sides of chisels and plane blades dead flat?
>  
> 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.

My question is, why does anyone polish the back sides of 
blades at all, with anything? If you need them flat, it's easy 
enough to keep them that way by laying them flat on the stone 
when you take off the wire edge from honing the bevel. I see 
no point at all to polishing the back, or the bevel, for that 
matter.


> 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. 

Yes. Very simple and easy.


>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.

It should be easy enough to make your initial wire edge on the 
Tormek, then move to the stones for a couple of final passes. 
The angle control is a feel thing. It comes with practice and 
paying attention.


>  > The control and precision required to fit traditional Japanese
>  > joinery is far beyond that needed to notch a bridge, or much
>  > of anything else we do to pianos. A notch scoop with only one
>  > nominally critical edge is somewhat different from maintaining
>  > straight lines and tight fits on three axes in a complicated
>  > joint in finish carpentry. And why would a plane blade need a
>  > hollow behind the edge under ANY conditions? As friction
>  > relief and fine depth control with a freehand chisel used in
>  > microfitting joints, yes. In a plane blade that is wedged in a
>  > block that handles the cut depth, friction, and presentation
>  > angle, what's the hollow for?
>  
> 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. 

The hollow on the back. At least according to photos I've seen 
on line, plane blades had that hollow too. Maybe not anymore. 
I don't seem to be able to find photos of much of anything 
like this on the Internet anymore, just general text , 
discussion lists, and offers to sell me books on whatever 
subject I'm looking for.


>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.
>  
> Is that what you were addressing?

No. I shape chisel and plane blades on a bench grinder when 
necessary, then hone on the diamond stone for that very reason.

But why polish?
Ron N