Grinding heat?

[ZOO]

I was wondering; while grinding on a new blade stock is it bad to over heat the metal? about how much can I do before I take a brake? is It better to have a water grinder to keep the steel cool?

zoo

 

[MaceG]

Dunk it when your thumb gets hot.

 

[Stacy E. Apelt - Bladesmith]

Before HT it only matters to your fingers.The steel won't be harmed.Be sure to stress relieve the steel before HT,though.After HT, don't let the metal become any hotter than your fingers like.Dip the blade in a can of watter often.

 

[ZOO]

How?? do you stress relive.

 

[Stacy E. Apelt - Bladesmith]

Before HT you need to relieve the internal stresses created during grinding.Heat the metal to critical temp (non-magnetic) and allow to cool on a fire brick.Repeat this one or two more times.The stresses should be gone.Then heat to just above critical and quench as normal for the steel you are using.Immediately after quench place the blade in an oven heated to 350 for about and hour.Let it cool to room temperature and repeat the temper again ( at the desired temper temp if you know it,or 350 as a guess).Clean the blade up and polish,being careful not to overheat the blade when finishing (and thus ruining the temper).

 

[Nomoemuny]

Be careful on the tips of knives exspecially if it is really thin. I was working on one that the tip was getting red hot and when I dipt it in water I guess the tip hardened enough to make it brittle because about 1/16 of the tip chipped off when I let the grinder grab it a little. It didnt leave my hand it just hit the tool rest and it shouldnt have been hard enough to break I doubt it was even hard enough to bend it but it chipped on me. It was an easy fix but now I go really slow and cool it often when Im working on the tip.

 

[ZOO]

Thanks everyone for your help