I am interested in one of these induction heaters. I make drill bushings by the hundred. Heat treating has always been an issue. I used to make them from 0-1 tool steel but now use A-2. My question is how would I know if they are heated to the right temperature? My mini furnace has a temperature gauge on it so it's easy now. The drill bushings vary in mass a lot so just using a timer probably would not work.