Cooling Steel

When cooling steel, the way and the speed at which you cool the steel can have a great affect and possibly even change properties of the steel.

This was prompted by a question as to whether you can use water to cool a Forstner bit while you are cutting. 

The answer is:  You can cool a Forstner bit with water while you are cutting, but doing so may cause other problems and you are just disguising the source of the real problem.  The best thing is to not allow the steel to get too hot.  Cutting with dull tools is a common reason that tools get too hot when cutting.

 Steel tools are not supposed to get hot.   Warm is okay, hot is bad.

Very simply, steel can have different grain structures. Depending on how you heat and cool steel you can change both the toughness and the hardness of the steel.


It is very easy to overheat the steel and accidently change the toughness and hardness.  My grandson learned about this process playing with one of my hotdog forks in a campfire.  I now have one hotdog for where the times are a lot easier to bend than they are on the others. 


The same affect that occured from overheating the steel in my hotdog fork can be applied to steel tools. You can even do it to tools without realizing it.  There have been studies showing that the edge of the cutting tool such as a saw blade or a router bit can reach temperatures over 1000°F.  This is hot enough to cause steel to change.


Depending on how hot you get the steel and how fast you cool it you can make the edge either harder or softer.  An edge that becomes much harder is much easier to chip, and an edge that becomes softer will dull much faster.

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