Wednesday, March 18, 2009

Das Messer-Projekt des Uber Jägers - Phase 2: Fun With Fire

And here we go.
As many of may recall from the previous post, this was the state of our blade when we left off. Forming is complete and it is time to begin the process of heating and hardening and heating some more to make things tough and flexible and really instill some of the qualities that are supposed ot make O1 tool steel such a good choice for this sort of thing.

First off the was the normalizing process. This is pretty simple but will burn the stuffing out of you if you are not careful. I myself decided to make a hanger in the basement and heat there. The idea behind normalizing is to begin to 'align' elements within the blade prior to the semi-traumatic experience of hardening. Normalizing involves heat the blade to a dull red and allowing it cool to handling temperature and then doing it again.

Once that process was completed, it was time to break out the forge. As you may gather from the photo here, this was a low budget affair. It's key components are:
  1. Galvanized bucket with a 1 1/2 inch hole cut in the side and the handle removed.
  2. A section of 1 1/2 inch drain pipe, duct taped into this hole.
  3. The hose from an old shop vac attached at one end to the drain pipe and on the other...
  4. A $10 Vidal Sassoon hair dryer from Walmart.
  5. On top of the bucket is placed a steel, deep skillet with 18 or so holes drilled to allow the air to travel into the fire.
From there, operation is pretty simple. I used matchlight charcoal for fuel and lined the skillet with crushed gravel to provide a bit of insulation for the skillet. (In my first run at this with this set up, the previous skillet melted away in approx 4 minutes. Thank goodness for thrift stores and a steady supply of pots and pans....) After allowing the lighter fluid to burn off the matchlight, I switched on the dryer and placed the blade in the forced air path. In approx 5 minutes the blade had reached the 1450 degrees required for O1 to become non-magnetic. At that point I switched the air flow to low and allowed it to bake for the recommended four minutes at that temp. After that, I pulled it and dunked it in that paint can full of oil you see in the background there. That, BTW, is a smoky, fiery, stinky mess. Do this outside if you are using oil.

Here's the blade and the firebox, post quenching. I've unplugged the air flow to the fire so it can begin to cool down.

The blade it a true mess at this point. Under all of that though, it is now hard as a rock if slightly more fragile. Once you wipe it down you find....

a blade slightly discolored but nothing a bit of sanding won't cure. This one made it through with no splits or cracks and no shattering. It warped ever so slightly but it is small enough that if I don't point it out specifically most folks will never notice.

Here we're midway through the tempering process. The blade has been polished and then heated to a constant 400 degrees F and then cooled. The spine has been heated with a torch to provide some additional flexibility. It's headed back into the oven for another 400 degree session. (big up to the wife for letting me use the cookie sheet and the oven....) This is the last step in the heat treating process and this can only mean one thing....

It's time to make the handles and finish things up. Here's the tempered and polish with 120 grit blade and the ironwood scales I will use for handles. I am hopeful to get to work on this in the next day or so. This is the most fun I have had in a while and it is way, way cheaper than building rifles....

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