I have a shaft to make for a mower gearbox. It has been unavailable for 30 years. I bought a piece of 0-1 water hardening drill rod and hardened it at around 1700° and tempered at 325° for an hour. The middle was file hard, ends came out soft. After more research another site said to harden at 1400° and I tried again, it is anealing right now and the ends seem hard now. Would the extra heat bozo the job? Double heat treat is good or bad? How hard is file hard at the minumum? This shaft has to roll on needle bearings and 58rC seems adequate, specs say I should be able to get 62-64rC. Doea all this sound right?