Making an Accurate Tempering Oven

I used a cheap toaster oven to temper my blades for a while now and was very disappointed in the results. I was only slightly more satisfied with our kitchen oven which is a pretty high quality one.
It was only when making observations with a dedicated oven thermometer that I realised that these ovens, especially the toaster oven, could be out by as much as + or - 20C which is catastrophic when attempting to achieve an accurate hardness.
A steel that would achieve a Rockwell hardness of 55 to 60 at 200C might only achieve 45 to 50 Rockwell at 220C which is no good. Yet my toaster oven, despite being set at 200C would creep up to at least 200C over a short time while a tiny degree of re calibration and the temp could settle at 170C.
It was time to sort this out.

Many thanks to Kostas Kalleris for, yet again, his help with all things electrical.
Music: www.bensound.com

WARNING: This video is for entertainment purposes only. I am in no way qualified as an electrician and do not pretend to be teaching you how to make your own PID controlled oven. Please seek help from a professional before undertaking electrical project.

Видео Making an Accurate Tempering Oven канала Dadsinhisworkshop