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-- heat treating plane irons

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Show Notes -

This is a somewhat short video on my experience learning to heat treat some small moulding plane irons. In the video I discussed some details gained from around the net. Here are some key facts:

  • The plane blanks are O1 tool steel. The 'O' stands for oil cooled so they must be quenched in oil, which has a higher boiling point than water so the shock isn't as extreme. I chose Peanut Oil because it has a high smoke point meaning less chance of fire.
  • Shape the iron before hardening them because simple hand tools such as a hack saw can cut it at this point. Also intricate shapes are easier to carve into the metal before it's hardened.
  • When heating the steel you must get it to 1450 degrees. Since most of us don't have a means of measuring that we use color to guesstimate. As the iron goes from dark red to a bright red, which happens quickly, it has reached optimal hardening temperature and is ready to be quickly quenched. We can also use the fact that when the steel reaches that temperature it changes phase and becomes austenite. At this point it loses it's magnetism so having a magnet handy to test this can reassure you that it's at the right temperature Above that temperature the iron will start turning yellow. I'm not sure what happens if you go too far in terms of the steels quality.
  • Tempering involves slowly heating the metal up to a specific temperature anywhere between 325 degrees and 400. The hotter you get it the softer it'll be. Tempering can be returned to as many times as you like in order to soften it more but you can't make it harder without starting over. So it makes sense to start at a low temperature and if that's too hard then go higher. You must keep it at whatever temperature for a few hours and then let it cool slowly. Many people use ovens, even the little toaster kind. Just be sure about the temperature with a thermometer because the dial gauges are not accurate. I use oil for a more consistent heating.

This was my first 'produced' video so don't worry, they'll get better. Things I know to work on: don't be listening to podcasts while filming, work on audio volumes, PRONUNCIATION and mumbling, and speeding up the talking head aspect so I can get videos down to 10 minutes. I'm also working on getting permission from a couple Celtic musicians so I can add some unique background music at appropriate spots. If there's anything you'd like me to work on please drop me an email. I can't fix it if I don't know it's broke.

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