My colleagues and I, every year, take part in a Secret Santa gift exchange. I wanted to make an original piece, and I initially opted for a Naked Kiridashi (download the design here).
I prepared two printouts of the kiridashi and cut them to fit a 5mm thick C70 steel bar.
I glued the outlines to the steel bar with vinylic glue. It works well for the purpose, but it needs to be used generously. It dries quickly, and it keeps the paper in place for the rough cuts.
The first thing I like to do is drilling the holes. While the bar is still square, it’s easier to clamp on the drill press.
At this point, I realized a knife was not the ideal gift. I have to ship it overseas, and most probably it will travel with me in one of my next trips. To avoid problems and make it more gift-friendly, I converted the design to a handy bottle opener. It will be even more appreciated for sure.
I did all the rough cutting with the angle grinder. After taking this picture, I realized that gloves, earplugs, safety glasses, and respirator were not enough. I added a hat to the outfit.
This is the outcome of the rough cutting. It’s getting in shape, but it’s quite not there yet.
After a more refined shaping on the belt grinder, we are almost there.
Even without a cutting edge, I preferred to proceed with a heat treatment to harden the steel. This high carbon steel is pretty soft if not treated and it would wear out quickly otherwise. I heated up the piece with two propane burners and quenched it in water. I immediately checked that my file was skating on the hardened section. I gave it a quick manual sanding to remove the oxide that formed during the quenching and tempered it at 200 degrees Celsius for an hour in the kitchen oven. This is the yellow-ish shade it got after the temper.
I roughly sanded up to 800 grits, leaving quite some tool marks on the surface. I am looking for a rough finish, so I didn’t care much to get a mirror finish. I marked the year and the initials on the two faces of the bottle opener with nail polish.
After a 10 minute bath in a water solution of ferric chloride at 40%, the hardening line is more evident than ever. The harder steel oxidizes to a deep black, the softer part has a lighter shade after the etching.
After removing the nail polish with acetone, the etching reveals its beauty.
After a vigorous clean with warm water, dish soap, and abrasive dish cleaning sponge, the black oxidation is gone, and the etching looks very cool.
Here the final product. Now it’s ready to get into a beautiful box and shipped to its ultimate owner.