Klom Knife set lock pick tempering

[Anavaree]

I recently got the set of Klom knife lock-picks from Locksmitharmy. We got to talking about how brittle the picks are and I though it might make a good project to see if I could re-temper the picks to make them more usable.
When I first got them I very quickly snapped the pick. Yes they are brittle.


My first hurdle was to determine the type of metal the picks are made of.
I used a primitive blacksmiths technique to narrow it down called spark testing.
You grind the metal and the type, color and behavior of the sparks can tell you what type of metal. not exactly of course, but at least put you in the ballpark. (Holy crap we need to clean the shop!)


I had stainless, mild and high carbon steel handy and compared them and decided that the pick is likely a medium carbon steel. More on that later.

Next step. Harden the metal. This is the easy part. Heat the metal to its critical temp, aka glowing, and hold it there for a bit.

Quench immediately.


Now comes the hard part. The pick is so small that controlling the heat into the metal was very difficult. It heated so easily. We want a spring temper in our picks for the most part. I needed to evenly reheat the pick to around 540F. Using the torch is not the best way. I will try to use an annealing oven to re-temper the pick properly, but I have to convince the engineers in the lab to let me lower the temp that low.
So I polished the pick to clean the surface and make the color change more visible.

Then I heated the pick as evenly and carefully as possible. Watching closely i tried to get a good color on it. This is the best I could get so far.

The difficulty I had in getting a nice dark blue in the metal also indicates that the metal is not very high in carbon. A higher carbon steel would temper easily and more evenly.

I will try again with another pick once I get access to the annealing oven.

Thanks
~Jesse

[LocksmithArmy]

Very cool work I hope you get it all wor4ked out cause thats one of the coolest looking sets ive seen mass produced.

[elbowmacaroni]

Yeah, it looks like it might have tempered unevenly.... nice chart on the spark patterns too btw, that should help alot of people... You should drop in the chat sometime, I have some questions about some freaky steel I have to anneals dead soft when it should be going brittle. I heat it to austenic and quench it and it turns to mush instead of shattering if you try to bend it. Weird stuff....

[escher7]

Nice to see an intelligent article on heat treating. As a former custom knife maker, I see a lot of B.S. out there. One thing I noticed is your reference to "glowing" as indicating critical temperature. What you are looking for is cherry red, which is a bright. red. You may have over-heated the metal. The other thing is that unless the steel contains at least .90% carbon it will not harden properly.