Composite Worm Gear Hob

[epanzella]

In an effort to conserve O1 tool steel I decided to make a gear hob that consisted of a mild steel arbor with a piece of O1 pressed onto it which will ultimately be the hob. Ironically my very first operation scrapped a piece of the O1 I was trying to conserve. I bored the 1.5 inch blank out to an inch oblivious to the fact that the 4TPI ACME thread will use up a lot of the wall thickness. I made another blank with a 3/4 minus bore and pressed that onto the 1 inch x 3/4 plus inch arbor.