gingery_machines @Wiki steel_core

machine#construction: casting#techniques: steel_core

Make a hole that's almost the right size without any machining.

Tips:
Coat the core with carbon from a flame so it doesn't stick. (*1)
Wrap fiberglass tape so it really doesn't stick. This makes the resulting core less accurate. (*2)
Don't use galvanized steel parts for the core (*3)