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Old 29-12-2013, 12:35 PM
Gareth Bull Gareth Bull is offline
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Join Date: Dec 2013
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Gareth Bull is on a distinguished road

Time to switch on the kiln! THIS was one of my best investments, not only does doing my own heat treat appeal to the OCD voice in my head but I can harden a blade up on a Friday night - might be a bit of a nerd.... oh well.

Green number is the kiln's current temperature, the red number is the target temperature. Little red ligh shows the elements are on

While the kiln is pre-heating I make a stainless steel foil packet - this stuff will cut you faster than anything I know - like a paper-cut on steroids I fold an over-sized piece in half then close up the long side first. I do two folds to make it airtight and tap the seam with a rubber mallet to make sure it's tight.

Now one of the ends, again, double folded:

Clean the blade with alcohol before placing in the packet:

Press out as much air as possible (it'll oxidize if you don't, this way the blade comes out a frosted grey that's very easy to polish)

The blade steel I'm using is RWL-34 so I heat to 1050*C and hold for 10 minutes, I then quench between two chilled steel plates (no photos - not enough hands!). As I type this it's chilling in liquid nitrogen overnight and I'll do the first tempering cycle (1 hour at 180*C) in the morning. I'll follow it with 4 more hours in the liquid nitrogen and another tempering cycle.
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