Scriber
I decided to make a scriber to attempt heat treating and coloring steel with heat. The design is a tube, collet and threaded end cap to draw the collet in. The scriber tip is made from 1/8" W1 tool steel. I chucked a piece in a cordless drill and spun it against the belt sander to shape the tip. I made the collet from a piece of 1/4" W1 tool steel. I turned, drilled and threaded it on the lathe and used a slitting saw in the mill to cut the slot. I used a small propane torch to heat treat the tip and end of the collet. It worked well, but I don't think it would produce enough heat for a larger piece. I tempered the tip to a light straw color and the collet to blue.
The tube and end cap were made from 12L14 steel on the lathe. My kitchen oven goes up to 550° F, so I decided to use it to color the steel. If I understand the process correctly, a thin oxide layer is formed as the steel is heated. This oxide, while black in color, is thin enough to be mostly transparent but it deflects some of the light. The amount of heat determines how thick the oxide layer becomes and what color is produced. 550° F should produce a blue color, but I pulled the pieces out of the oven too soon and they had yellowish-brown color. I decided to put them back in for a longer time to get blue, but they just turned brownish-black. I probably should have sanded the oxide off and reheated them, but I decided to leave them brown. I am guessing that the second heating created a separate oxide layer instead of making the original layer thicker. If that's the case, the break between layers would explain what happened with the color.
The tube and end cap were made from 12L14 steel on the lathe. My kitchen oven goes up to 550° F, so I decided to use it to color the steel. If I understand the process correctly, a thin oxide layer is formed as the steel is heated. This oxide, while black in color, is thin enough to be mostly transparent but it deflects some of the light. The amount of heat determines how thick the oxide layer becomes and what color is produced. 550° F should produce a blue color, but I pulled the pieces out of the oven too soon and they had yellowish-brown color. I decided to put them back in for a longer time to get blue, but they just turned brownish-black. I probably should have sanded the oxide off and reheated them, but I decided to leave them brown. I am guessing that the second heating created a separate oxide layer instead of making the original layer thicker. If that's the case, the break between layers would explain what happened with the color.