That old timer was right about quenching in used motor oil...

I was working on a railroad spike knife a few months back, nothing fancy just a little project for a friend. An old guy named Carl who's been forging since the 70s told me to ditch my fancy canola oil and try used motor oil instead. I thought he was crazy, figured it would smoke like crazy and mess up the hardness. Finally gave it a shot last week with some oil from my buddy's 98 Ford F-150 and dang if he wasn't right. The quench was way more consistent, no huge steam pockets or uneven cooling like I always got with the canola. The spike came out harder than anything I've done before, filed right through my test file without biting. Anybody else use weird quenchants like old brake fluid or something? I'm curious what else works that people look down on.

2 comments

2 Comments

sandra_black17d ago

You ever try used transmission fluid? I did once on a small camp knife and it worked better than I expected, less smoke than motor oil too. The trick seems to be anything with a bit of use in it already, the contaminants help with the film boiling or whatever. Just don't breathe the fumes too much, that stuff is nasty.

anthony_wells16d ago

Huh, I tried it on an old axe head once and the neighbor's dog wouldn't stop following me for a week.