About forty years ago I did some hobby knife making, starting out with the cheap Sheffield blades sold by CVA. I’d silver-solder a brass guard on the blade, then epoxy a Micarta handle onto it. Really easy. I probably put no more than four hours into each knife and the satisfaction index was way high. Eventually I realized that the carbon-steel blades from Sheffield were really of poor quality, so I decided to take the next step.
At that time, what with no internet, there was very little info out there and hardening a blade was the major barrier to an amateur like me. I did a little research on the steels used for knives and found that D2 tool steel could be air-hardened. This meant you only had to get it up to temp for a while, then let it cool down by itself. After hardening, I’d stick it in my wife’s oven at 400F for a couple of hours to temper the steel. The first few knives I did this way turned out quite well. I had one checked for hardness by the machine shop at work and it came back at RC59. Unfortunately, it also came back with a deep pin-prick in one side – way too deep to fix. Their tester used the depth of penetration of a diamond stylus to estimate hardness. I tossed that blade out. I made several knives that way and was really pleased with the results. They went to good friends as gifts. One skinner went to a Wyoming rancher who says he still uses it.
Fast forward to today. When I retired in 2006, I made a list of the hobbies I might get into and knifemaking was one of them. I started out by buying a really good Jet pedestal buffer, but I really needed a metal band-saw to cut out blanks of D2 tool steel and a belt sander to do the shaping. Either one was out of reach for my hobby budget – I was spending too much of my budget on Wicked Edge stuff. Eventually I bought a cheap Rikon 6X48 belt sander with a 10” disk. This spring I finally bought a really cheap bandsaw at Harbor Freight. With their 25%-off coupon, I paid about $200 with tax. It works really well for my purposes and this finally got me started. I don’t have any fixtures, so all of my shaping was strictly hand-held work. Not real pretty but good enough.
My first project was a replacement blade for a Spyderco Resilience. I wanted to tackle the fitting issues of a liner-lock folder. Hopefully, when I’m done, I’d have a $50 knife with a higher quality steel in the blade. But mainly, it was a test of whether or not I could harden a D2 blade with a propane torch. All my hardening back in the ‘70s was with an oxy-acetylene torch. I didn’t really like the shape of the blade that comes with the Resilience, so I made the D2 blade closer to the shape of the Stretch.
My first try at hardening didn’t go so well. The torch on MAP gas simply didn’t have enough BTU’s to get the whole blade up to temp. Rather than getting knee-deep in an oxy-acetylene rig, I decided to try two torches on MAP gas. How coordinated can I be? With the blade hanging from the basement ceiling, I lit both torches and tried to get the blade up to a bright orange glow, but couldn’t quite get there. Was I at the critical temp? How could I check for magnetic attraction when I’m holding a MAP torch in each hand? I set the torches down and reached for my test magnet – super-glued to a carpenter’s pencil. Surprise! No magnetic attraction and the blade wasn’t even red anymore! I let the blade hang unmolested for an hour or so before checking it for hardness with a mill-cut file. The file skated over the steel and I could see clearly that I had actually accomplished what I had set out to do. Wow! To temper the blade, I put it in my wife’s oven at 400F for an hour and a half (I wanted something harder than RC59). I don’t know how hard it is, but when I tapped the blade on my granite plate, it sure sounds hard. Ding, ding!
One important lesson here was that I didn’t have to go as high in temp as I thought and I didn’t have to hold it there. The importance here was that the lower temp causes little or no oxidation on the blade surface. With the oxy rig, I had burned the surface pretty good and had to spend a lot of time sanding and buffing out the rough surface. Not so with the lower temp. All of the data you find on hardening D2 calls for a long soak at temp. But with a slender blade like this, any heat on one side is almost instantly felt on the other side. I only held it at temp for maybe 30 seconds.
Data on the internet says that at the bright cherry red I reached, the temp was just over 1800F. Hardening D2 requires that you reach a temp of 1800 – 1850F. Knives I hardened back when Elvis was still kicking were heated to orange-red, which explains why the surfaces were burned. Orange-red is over 2000F. The tempering at 400F should produce a hardness of RC60, which was my target.
Here’s the Spyderco Resilience showing the guts.
Here’s the completed knife with the D2 blade installed and with the original blade shown as a reference:
I used the original blade as a template for the critical dimensions. I had to buy some small metric drill bits and a 5mm reamer. I had to “sneak up on” the lock fit, but it really wasn’t that difficult.
The last photo shows the D2 blade sharpened to 1000 grit. My handiwork on the blade was a little too crude to warrant a mirror edge and I didn’t want to accentuate the unevenness of the bevel width. With my belt sander I couldn’t get the area just forward of the ricasso to the same thickness as the rest of the blade. This is for the same reason that it’s difficult to reach the ricasso with the WEPS.
I know this is a really long-winded post, but my intent here is to show others here on the WE forum that you can do this stuff with a very limited amount of shop tools. If you got this far, thanks for your attention!
