03 April 2010

Intersection

































I had a parcel from Matthew the other day and parcels of any sort, especially if they contain shiny tools are always welcome. This one contained a couple of Mr Fujikawa's finest.... a 24mm hooped and paring chisel. One the face of it, they looked slightly disappointing languishing in the box...no straw filled cardboard box, no highly polished exotic timbers for the handle, blades that clearly had the forging marks still visible with a quick lick of matt black paint applied, hoops roughly forged and banged onto a fairly ordinary piece of red oak. To all intense and purposes then, a pretty mediocre looking tool with nothing of the sheer gloatworhy and drool inducing anticipation of the Blue Spruce brand.

But, as we all know...appearances can be deceptive, very deceptive.

I decided to make a start and ground in a small depression just behind the blade. This so that it doesn't foul the edge of the stone during the back flattening process (which is the best way I know to crumble the edge of a waterstone) after which I began the time consuming and somewhat laborious process of bringing the back to a mirror finish...even with the ground depression in the back, it took me about two hours, mainly due to the 'bump' just behind the edge which most of these chisels have. This must be removed to leave a dead flat or concave surface.

Having finally polished the back using the .3 micron 3M paper I started on the bevel and kept (as recommended) to the single bevel of 30 degrees. Eventually, after working through the 3M papers, finishing with the .3 micron again...I had an edge. Restraining my urge to test it, I then set the hoop, using the excellent notes provided at 'Tools for Working Wood'

How do you test the edge though?

One of the big worries with these sorts of chisel is that the edge will be too brittle and shatter. These chisels are hardened to an eye wateringly, truly insane RC68, which about as hard as you can go without case hardening, so it was with more than a little bit of trepidation that I thumped the hooped chisel into a scrap of English Oak...35 times!

Not a sausage, zip, rien...nowt!

The edge remained perfect and merely seemed to laugh at my utterly feeble attempt to impart some damage. I then tested it by taking some shavings across the corner of a soft piece of pine...some test for even the sharpest edge. Mr Fujikawa's chisel took the finest, whispiest shavings that I've ever seen...with the merest, lightest touch of the blade. To be fair, I honed a LN chisel and tried the same thing, with a similar result...except that a lot more effort was needed. A2 steel is good, but when you consider that a sharp edge is the intersection of two surfaces and nothing else, Mr Fujikawa's chisel is a whole magnitude of sharpness better...














I've made some progress here on the parer, but as you may be able to see from the pic, there's another hour on two's flattening to do before it's done.

Onwards and upwards.

6 comments:

Tico said...

Can you describe your set-up for grinding that depression in the back?
On the bevel of Japanese plane irons I have seen one craftsman use a Dremel tool with a dental bit to hollow out a fraction of material.

Thanks,

tico

Woodbloke said...

The depression is already ground in the back during the manufacturing process...in theory it makes flattening the back easier.

That's theory.

Practice is different.

Mitchell said...

Wow, that is a lot of work for a hundred dollar chisel. I didn't see that coming.

Tico said...

I googled Fujikowa chisels and nothing came up. Where are these chisels available?

Tico said...

I believe it must be Fujiwara.

Tico said...

Apologies, I see from your earlier posts the sources of these chisels.