3D touch probe confusion

JohnnyCNC wrote:

I don't have a surface plate or height gauge (yet). I do have a lathe with a DRO. I made a ring that the tool holder fits into. I chuck the ring up the lathe, Turn the lathe tool post holder around so I have a flat surface that will go up against the ring. Zero out the DRO. Move the tool post away from the ring. Insert the mill tool in the ring then move the lathe tool so it touches the tip of the tool. The DRO now shows the tool length. I enter that value into the tool table.