Japanese Nata

U

Utican

Joined
Sep 18, 2010
Messages
215
While waiting for arrival of 1/8" flat in 1084 I am toying with an idea of a Nata style chopper in (single bevel). I have 1084 in 1/4"x 1 1/2" and will make the blade about 8" possibly 9".

The questions I have are:

1. what grind angle is suitable for a blade this size and this application.

2. My quenchant is canola oil. Will a gallon be enough and in this cross section is it fast enough?

3. What hardness should I aim for the blade of this purpose and size.

I would appreciate any input regarding this matter.
 
If I made one with that steel...

20* chisel grind

For your canola oil first find a container you will quench in and make sure you plenty of room on all sides, then add your Canola Oil and heat it to about 120-130*

Hardness for a chopper 57-58
 
This was long time in making. Im am encountering warping issues. I have ground the blade pre ht due to the thickness of the stock. It came out warped, bad. Any advice one how to counter the bend. I attempted to straighten during temper with negative result. I will be re doing the ht on it.
 
Dull back the edge a bit more to assure that isn't the source of the problem. Spheroidize the blade before re-doing the HT. Straighten it as good as possible. Re-do the HT with full cycling, and straighten right out of the quench ..... By hand (with HT gloves on) between 900F and 400F. During this window you can hammer, twist, bend, etc. to your heart's content with no fears. Putting a hardwood board on the anvil makes the blade not cool too fast while hammering it straight ( if needed).
 
Thank you, it worked like a dream. This is my first time making a such blade out of 1/4" stock. It is straight but bent towards the edge. I will leave this one as is for now. In future is there any way to avoid this drooping so to speak for lack of better term?
 
The downward curve is caused by the cooling rates of the metal as it converts to martensite during an oil quench. In water, it often curves upward. On smaller blades, it is minor or unnoticeable, but on large blades and swords it can be a problem. Many smiths add a reverse curve during forging/grinding to make it comes out straight after the quench.

It can be ground straight and the bevels re-profiled if not too bad.
 
Thank you, I will try that with next blade. Im making this one for myself and actually like the shape as is. I think it will compliment the angle of the handle as well. The handle will be mortised local black wallnut. The blade is 9". Is 3" of hidden dang with one pin enough for a blade this size?
 
There will be photos soon. I got sidetracked by making couple of Nessmuks and two Pukkos for friends and family. I am pleased with blade preformace. I abused it by hamering it across grain of a seasoned oak piece and no failures, just one dull spot about hald inch long. No chipping!
 
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