Sharpening Japanese chisels

[SteveZ]

Anyone have any favourite methods for sharpening Japanese chisels? (and before anyone suggests it, I've searched the threads here and not found anything spefically about Japanese chisels).

I've read on the Web that you are not supposed to hollow grind Japanese chisels because the steel is different, but haven't come across any details about what you are supposed to do.

Any suggestions. BTW this is my first post so treat me gently!

[craigb]

First of all, welcome steveZ. :)

Second of all; please dear God, not another sharpening thread :eek: :rolleyes:

My best advice to you would be for you to send a Personal Message to Derek Cohen. He is by far and away THE sharpening guru on this board.

What he doesn't know about sharpening can be written on a 2 micron plane shaving ;)

[Dan]

Or, you could just sharpen them the same way you sharpen your other chisels. Just leave out the hollow grind if you normally use one. Are you sure you had a good look around? Here's Major testing out his new sharpening guide on a Japanese style chisel.
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=15800

[derekcohen]

Hi Steve

There is nothing mystical about sharpening Japanese chisels (although chanting and facing East may help).

The points to remember are that

(1) the blades are laminated steel, and this comprises a thin hard steel and a thicker soft steel layer. If you attempt to hollow grind the blade, you will remove hard steel, and this may undermine the strength of the edge. Having said that, David Charlesworth hollow grinds his Japanese chisels. Admittedly, his is a complex system of three microbevels, so I would just ignore his method at your stage of the game and concentrate on a more fundamental system.

(2) the nice thing about Japanese chisels is that the blades are thick and you can freehand them quite easily. However, I am going to assume that you will use a sharpening guide.

(3) you need to grind the primary bevel at 30 degrees, then add a secondary (i.e. micro) bevel of 2 degrees.

(4) while waterstones are best for sharpening (cut fastest and offer the highest grits) and diamond stones the least desired (most unforgiving - hard -surface and may fracture the edge), you are really free to use whatever you choose. Sandpaper is probably the cheapest setup for a one-off, but gets expensive over time.

(5) a basic set up is either two waterstones (1000 and 6000 grit) or three (800, 1200 and 6000 grit). An alternative to the 6000 stone is a 8000, but this does cost 3 times as much for not a great deal more in the sharpness stakes. I like to hone the end result with Veritas green rouge (just rub some on a piece of MDF).

(6) grind the primary bevel to 1200, then the secondary at 6000 (note - this only needs to be one mm wide, so it should not take long). OR, if you want to just grind one bevel, then run through the grits to 6000 (this is more work since you are now sharpening the entire bevel to 6000).

(7) there are two items to keep an eye on: Firstly, the waterstones must be flat before you use them. This is easy to do on 220 grit wet-and-dry or drywall mesh. Secondly, obtaining a clean primary bevel is the most important step in sharpening proper. If you do not sharpen right to the edge of the bevel, then all you will end up with is a polished, rounded edge - not sharp. Lastly, the back of the blade must also be flat ("sharp" is the coming together of two edges).

Hope this helps.

Regards from Perth

Derek

[routermaniac]

First of all, welcome steveZ. :)

Second of all; please dear God, not another sharpening thread :eek: :rolleyes:

My best advice to you would be for you to send a Personal Message to Derek Cohen. He is by far and away THE sharpening guru on this board.

What he doesn't know about sharpening can be written on a 2 micron plane shaving ;)
go on, you know you were just waiting for that sharpening thread :D :D :D :D :D

[outback]

So Derek, when does three micro bevels not equal a radius? :D . Seriously, if you weren't awful careful thats all you'd end up with.

[derekcohen]

when does three micro bevels not equal a radius?

Outback, the idea is to reduce the amount of honing (which thus reduces time) and focus it only on the needed area (which reduces effort).

Consider: a 25 degree bevel ground at 800 waterstone, followed by a 3 degree micro bevel (equals 28 degree bevel in total) honed at 1200, followed by a 2 degree micro bevel (equals 30 degree bevel in total) at 6000. The first microbevel may be 2 mm wide, the second only 1 mm wide. Not a lot of sharpening/honing done, yet the important area - the cutting area - is sharp.

Repeat honing is only done at the micro bevel level.

This might be done for both planes and chisels. Depending on the flatness of the plane blade (NOT to be done for chisels), you may add a micro back bevel (of 1-2 degrees). I am referring here to David Charleworth's "Ruler Trick", but will not go into details here, suffice to say that it saves the time and effort of flattening the back of an out-of-flat plane blade.

Regards from Perth

Derek

[bitingmidge]

So Derek, when does three micro bevels not equal a radius?

Seriously too:- is that why a LOT of old chisels and planes ARE radiussed??
Were the old fogies actually making less work for themselves??

Just curious, maybe I've wasted heaps of my life grinding things flat for no reason.

Cheers,

P

[derekcohen]

is that why a LOT of old chisels and planes ARE radiussed??

Nah, that is from freehanding the blades over the sharpening medium. There is the inevitable rounding of the bevel.

Regards from Perth

Derek

[SteveZ]

Derek and Dan

Thanks for the advice, much appreciated.