Previously in Part 1, I covered the initial machining of the iron from an old file.
For some reason I had thought I had taken pictures of milling the bevel but I did not. I decided to mill the bevel at 30 degrees and just clamped the iron in the vise at a 30 deg angle and used a 3/4 end mill to machine the bevel. This worked out quite well and left me with a very true bevel. Here is the result after milling. You can see there is a slight bur left on the edge but that will get knocked off later.
At this point the blade is ready for heat treating. To start the process I heated the iron with the torch while holding it with a pair of blacksmithing tongs. Once it reached a red heat I held it there for a few minutes making sure not to overheat the cutting edge.
Once the blade had soaked at a red heat I then dunked it straight into a can of old motor oil. Care needs to be take that you put the iron into the oil straight so that it cools uniformly. If you submerge it crooked or not all the way in the oil you can cause the steel to cool unevenly which can warp the iron.
After quenching the iron in oil it is very hard and fragile. To give it more strength it needs to be tempered. First I rinsed the iron off with water and remove the oil. Then I put it in the oven at 350F for 45 minutes to temper it down to reduce the hardness and brittleness.
After the tempering cycle was complete, the iron was allowed to cool in the oven to room temperature. Then it was pulled out and the bevel cleaned up and quickly sharpened with first 220 grit sandpaper followed by 600 grit sandpaper to remove the scratches from milling the bevel.
The backside of the iron showing the uniquely rounded end.
That concludes making the plane iron from a file.
Next in Part 3, we will start making the wooden plane body from some scrap red oak.
Until then please feel free to comment and ask questions if you have any.