cold temperature sharpening

[reas]

Hy !

I found a video on Youtube where a knifemaker sharpens his knives on diamond coated wheels at -110°F.

Why is he cooling down the knife to that temperature, is it just to prevent the knife from overheating ?

btw sorry for my bad english i´m not a native English speaker


This is the link to the video:
https://www.youtube.com/watch?v=g4b_2WHcXFw

thanks

reas

 

[Obsessed with Edges]

He actually mentions at ~ 3:55 into the vid that he cools the blade to keep it from losing it's temper at the edge, by overheating. Cooling the blade is normal for most pro/experienced sharpeners using powered grinders; most just dip the blade in water or some other liquid at room temp, though he obviously is taking it even colder. I have no idea how much difference that makes, but it certainly couldn't hurt.

Being that he's using diamond wheels, it may also serve to protect the diamond. Diamond is known for breaking down (losing it's hardness) at the extreme temperatures generated by powered grinding systems. Anything that can prevent it from overheating will save a lot of expense in replacing those wheels.


David

 

[Bill DeShivs]

Heat doesn't hurt diamonds-as long as they aren't cooled quickly.

 

[Obsessed with Edges]

Diamond breaks down into less-hard forms of carbon at temps above ~ 600°C (to carbon dioxide and other forms, like graphite). It's also reactive to iron at temps above 700°C, if grinding on steel; that can cause the diamond to erode. If grinding temps don't approach that, no worries. Overheating during grinding is the reason CBN is usually recommended over diamond for powered grinding on steel (ferrous materials), because CBN is more stable at high grinding temps up to ~ 1300°C, and is also non-reactive to iron at high temps.

I've no idea whether the grinding example in the OP's video is capable of approaching such temps in that usage; maybe it doesn't, but it's worth considering and is why I mentioned it.


David