In my wooden screw making efforts a “Eureka!” moment came with the realization that the thread cutting tool can be made of two rectangular blanks clamped together to form a V-shaped cutter. The material is High Speed Steel M2 lathe tool blanks. The two part cutter is easier to make and easier to sharpen.
Here you can see a cut being made.
The screw has been backed off a little to show the V-shaped shaving. Thinned raw linseed oil is applied to the screw while the thread is being cut. This softens and lubricates the wood and helps the cutter stay sharp much longer.
Timothy Moore Bookbinding Tools 