Background: My comapny has inheirited a 30+ year old Cheston electrical resistance heater that was originally capable of heating 5/8" and 3/4" 1015 carbon steel bars for forging (temp = 2200F°).
Problem: the machine heats the 5/8" with no problems, however when running 3/4" bar, cratering develops on the work pc.
What we have done so far:  Cheston is out of business, ASM manuals do not cover elec resistance heat well, everyone I know has gone to induction heating, changes to the machine such has temperature settings, soak times, contacts, seem to not effect the outcome (3/4" bar cratering).
Question: Anyone have experience with elec resistance heating for forging? Any suggestions on how to get 3/4" running as well as 5/8"?