DIY Hardened gears

Originally Posted by kona

I haven't had any problems with not tempering. I don't know if tempering is necessary since this is case hardening and only the very thin surface layer is hardened. The bulk of the part should be low carbon steel and therefore does not harden.

I also haven't had any warping, but it could be a problem especially with larger parts.

I am not familiar with the powder coating ...maybe using it does protect it somewhat, the part would be more prone to warping if you went directly from heating to quencing in water. When you quench in oil it lowers the temp slower decreasing the chance of warping and cracking, oil is also a good source of carbon