Hardening a huge saw blade - GIF

Hardening a huge saw blade.

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Previously:

Crankshaft hardening machine - GIF
Induction hardening a part - GIF
Induction hardening a toothed part - GIF
Laser hardening a large gear - GIF
Laser hardening a part - GIF

Harry Potter and the huge saw blade...

are they using electricity between the blade and the quench media to heat the teeth/rim in order to harden it? - kinda a differential hardening.