Leo's video on How To Sharpen Edge Tools.


This isn't really about Tally Ho per se, but is important and pertinent none the less.

It also maintains Leo's episode numbering.

 

Leo skipped rather lightly past the issues of tempering and if you follow his instructions, that's likely OK, but I'll add a little more here.  He mentions the tool "going black", but steel actually goes through a range of colours as it heats and those colours tell us quite a bit about what's happening to the metal.  If we make the metal very hot, around red-hot and then quench it (plunge it into cold water or oil), it will go very hard and very brittle. You may then get a sharp edge, but it will likely soon chip away.  So after hardening, we carefully polish the metal again, ensuring that we don't overheat it, then we heat the metal to a colour ... for sharp cutting tools, that colour is usually "dark straw" and again we quench in cold water or oil.  After that, we polish again and whenever then sharpeining we stay below that dark straw colour.  If the steel goes as far as blue, it will then be too soft to hold a sharp edge.

Tempering Colours on Wikipedia

Gordon.


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