Friday, November 14, 2014

KN9 - CHEF'S KNIFE PREP & HEAT TREAT

Some knifemakers call this a drag, but I find it quite relaxing.

I like too use a toggle clamp to hold the blade down. I can sand one side of the blade and quickly flip the blade over. It's the cat's meow. I have more ideas on my Shop Jigs & Fixtures page.
Normally I start at the grit I left off with on the belt grinder. If some gouges are deep, maybe roll back a size or hop back on the grinder to clean them up.
Window cleaner is my lubricant of choice for hand sanding. Periodically wipe and give it a quick squirt and start again. Pieces of sand paper will last a few minutes each, so keep plenty handy.
Here's what the blade looks like during the hand sanding process.
Near the end of hand sanding I like to look at the blade and use the reflections to make sure that no rough spots exist. At this stage I am working at 320 grit. Once it's clear we can move on to handle prep.
I really liked how the oval pattern worked on the KN7-2 and wanted to carry some of that skill into this version.
The front bolster will follow the same curves and the scale inset. Note the marking for holes is in a straight line from bolster to bolster.
A punch is used to make sure the drill bit doesn't walk away from the intended spot.
When drilling the holes in the tang, some cutting fluid and a cobalt bit works wonders.






Once drilled, I wrap the blade in stainless steel foil.

Now into the oven for a soak. The target temperature here is 1060°C for 20 minutes. This will vary with steel, but 154CM will be fine at this temp.






Out of the oven and immediately into the plates for quench. You can see some slight oxidization on the blade, but nothing that can't be cleaned up with a light sanding.
Once the blade is cooled to around 50°C (122°F), it goes immediately into the tempering oven at 200°C (400°F) for two hours, cooled and a repeat 2 hours at 200°C. This should produce a hardness around 58 to 59 Rockwell C.



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