"Pete C." wrote in message
...

Ed Huntress wrote:

The next step down is flame-hardened gears. These are made from
high-carbon steel, or a quick-quenching high carbon alloy. This flame
hardening requires a fixture and a quenching system that surrounds the
gear all at once -- a spray-type or an agitated oil bath.

So spin the gear on a mandrel with just the teeth in the O/A flame until
red hot and then quench it in some carbon rich used diesel oil?

You need to have a carbuerizing flame ( IE lots of soot ) if you want to add
carbon, (or if you do not wish to lose it )

IIRC, you can flash copper plate, as carbon will not pass through a copper
barrier but you probably better double check me on that.