DiResta: Kitchen Knife

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DiResta: Kitchen Knife

knife

I have been experimenting with knife making! There is a science involved in the hardening, and I am slowly learning the various techniques. This is a piece of O-1 oil hardening tooling steel I purchased from OnlineMetals.

To shape the piece I used an angle grinder. To refine the shape I am using my 2″ร—72″ Beaumont belt grinder. Making the bevel consistent on both sides is important, so I used a plank of wood with a 5ยฐ angled face to keep the steel at the same angle. I keep the steel against the face of the board with a screw clamp. On the plank, I use two screw clamps as a stoppers against the sander’s plate; this keeps the grind consistent and neat.

I take the grind to 95% before hardening, and after hardening I sharpen and polish. The belts start at 60 grit and by the end of the grind I have moved through 100-250-600-1000 grits. For the final sharpening I polished the cutting edge until it is razor sharp. Thank you for watching!

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I like a large, sharp knife when I cook so I decided to design something sexy for my kitchen. I began by freestyling a shape on a piece of O1 oil-hardening tool steel. I have some cool knives whose shape I mimicked, but I gave this one an extra long handle for better control.

CUT

With a cutoff wheel on an angle grinder, I removed the negative space on the handle and the taper to get a vague shape. I went way off the sketched line and cut more of a taper than I expected, but it gave me a long, sleek look that I was happy with.

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Shape

I refined the shape using a 60 grit belt on my belt grinder. The combination of a top-curve down and a bottom-curve up gives it a nice centered look.

CAUTION: Wear a respirator when grinding metal to avoid breathing in the super-fine particles. Theyโ€™ll stay in your lungs and get rusty.

Bevel

To keep the bladeโ€™s bevel balanced on both sides, I coated the blade edge with machinistโ€™s blue layout fluid, allowing me to scratch a line for the bladeโ€™s center. Next I took a chunk of wood with a 4ยฐ or 5ยฐ bevel to use as my sled. I attached the knife blank to it with a screw clamp placed just a few inches beyond the back of the blade. The clamp served as a stop against the back edge of the grinder table, creating an unground part so my knuckles wouldnโ€™t hit that very sharp back and get cut.

To get the bulk of the bevel shaped, I slid the knife blank โ€” first one side and then the other โ€” slowly back and forth across a 36-grit belt, letting the blade cool from time to time so as not to burn the wood.

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I ground a steep, long bevel about 2″ from the very sharp cutting edge to the wider back of the blade. This took a long time.
Once I got almost all the way to the other end, maybe about ยพ” before the back of the blade, I unclamped the knife from the slide and switched to a 250-grit belt. Using a piece of wood to press the blade against the belt (it gets too hot to hold), I slowly worked that bevel in to the other side โ€” at this point the blade was roughly 90% to where it needed to be.

Heat Treat

To harden the knife, I held it with tongs by the tang and heated it up to bright red (1,425ยฐFโ€“1,450ยฐF) in a forge and then quenched it in vegetable oil, just because I was working outside and motor oil is bad for the grass. When finished, I sanded off the slag with a 250-grit belt, and then tempered it in a 400ยฐF oven for about 1 hour.

Build and Attach Handle

The handle is held in place with pegs. To make it, I centered two marks on the knifeโ€™s tang, drilled small pilot holes, then enlarged them with a โ…œ” bit. Then I cut two pieces of Macassar ebony to the size that I wanted, temporarily glued one onto the tang using a small amount of CA glue, and used the holes I cut in the metal to drill through one side of the handle.

Once cooled, I glued on the other side, flipped the handle over, and drilled back through the holes. I stuck wood pegs through the holes to keep the handles in place while I hand-shaped them on the band saw. I like the simplistic look of the blade, so I also wanted the handle to be a simple round shape. To work around the bladeโ€™s height, I propped it up on a chunk of wood so that I could poke it straight into the band saw blade.

Using a V-block to keep the knife in place, I shaped the handle further with a Japanese rasp, did some final sanding, and then popped out the wooden pegs. I glued all the pieces back together with significantly more CA glue, coating the metal pegs and hammering them into place.

I used a jewelerโ€™s saw to cut the pegs, and then ground them, nice and smooth, down to the surface of the wood.

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Sharpen

Finally, I buffed the knife to give it a nice, razor-sharp edge from end to tip, using a buffing wheel.

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As I often say, I am the god in the world of this knife โ€” if it becomes dull I can certainly sharpen it. It halved my dinner like a hot knife through butter. Or, more accurately, a sharp knife through a burrito.

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