Putting a "real" yokote on a modern katana that wasn't "born" with one

[duxbellorum]

The tip of this Hanwei Practical Plus Elite Katana

Had an obviously fake yokote (some scratch marks perpendicular to the edge, but definitely no actual geometric distinction). The sword had been used to cut tree branches and silly stuff for a long time and had accumulated some major cips, pits, and damage, so I have put a lot of effort into remaking it to the extent in the picture (done with my lowest grit stone)

I would like to put a "real" geometric yokote onto the sword. This is turning out to be a lot more difficult than I had hoped, trying to hold the sword at a consistent enough angle while working it perpendicular to the edge.

Is there a good technique to it? There are some polishing videos out there, but no videos that I have found of someone actually making a geometric yokote from scratch, so if someone had such a video sitting around, that would also be helpful.

Thanks!

 

[Jason B.]

Difficult to near impossible is the skill level here. You would need tape off where you wanted the line then distal taper to the tip. This would take days/weeks of careful grinding to get right if your lucky.

A good assortment of Waterstones and finger stones would be necessary.

 

[duxbellorum]

I had very little time over the last month or so, but I finally got around to working on this.

All told, I have spent about 40-50 hours working on the sword, 25 hours of that went to fixing the overall geometry of the sword including 10 hours or so spent working on the yokote. The process was simpler than I would have thought, so I did all of it free hand, just held the handle end of the sword up to establish the angle I wanted for the bevel at the tip, and ground the tip back and forth unti I had established that angle uniformly. The one trick I used to help check that I was removing metal from the right place was to periodically color the tip with sharpie, grind, and take a look. I found it easy to raise my arm too high, and start removing metal from the point of the sword, rather than just in front of the yokote. Eventually I got a feel for where I was on the tip and was able to dispense with this step.

I am not completely satisfied with the results. The yokote on each side do not meet, the lines are off by almost a millimeter, and the amount of metal I would need to remove to really fix that would be substantial. I will loosely blame the resulting asymmetry on the originaly asymetry of Hanwei's grind near the tip. I forgot to take some "before" pictures, but the right and left hand bevels were originally very different, extending about 2mm wider on the right hand side than on the left (so the shinogi line (ridge above the bevel) was about 2 mm closer to the back of the sword on the right side than the left). Apparently the Chinese craftsman who made the sword used different techniques for the right and left grind. I chose to solve this by grinding the left hand bevel until the shinogi line matched, and then adjusting the entire bevel to maintain that shinogi line on the left hand side.

Video of the Sword (please ignore the mumbling in the background, the holidays are not a quiet time where I live)

The other major feature that I noticed about the sword as I started adjusting the shinogi line on both sides was that the shinogi line (and the depth of the bevel) undulated slightly down the length of the blade. I think this is a result of the original grind being done on a high speed small diameter wheel, rather than the traditional large diameter wheels used in higher end swords. I ended up removing a ton of metal from the bevels on both sides to standardize the geometry. Even so, you can see in the video that the shinogi line still is not consistent (it wobbles...). If I ever had to do this again, I will cough up money for a high end belt sander. I did this entire job by hand on stones, and It was just too much work.

In the future, I may end up finding some uchigomori or hazuya stones to properly bring out the hamon and finish polishing. I have stropped the bevel pretty well so that it will bead water, and the edge itself is insanely sharp (there is no section that one cannot shave with). Perhaps after it has undergone some use/damage, and needs a touch up I might take the time to really finish things up.

If anyone is curious, I can talk more about what techniques I used to sharpen the blade, which stones, which hand movements, how I maintained a good convex grind, etc...

 

[HeavyHanded]

All in all it turned out pretty good, I'd be happy with that. Would want to practice with that a few times before attempting a higher end piece, but for the difficulty level and underlying geometry issues it came with, it turned out very well.