Why nobody talks about quenching in used motor oil

I was struggling with getting a good hardness on my smaller tools like chisels and punches. Tried water, tried brine, always got cracks or soft edges. Then an old timer at the shop told me to try my used motor oil from my truck as quench. It's slower than water so less shock, but fast enough to harden 1075 properly. Has anyone else tried this or am I just lucky it worked out?

2 comments

2 Comments

shane24429d ago

Used oil has all that carbon buildup" - that's exactly why I switched to old atf fluid for my punches. It's got a real consistent quench speed and I haven't cracked a single tool since.

diana82929d ago

Man, you're onto something! Used oil has all that carbon buildup and fine metal particles suspended in it, so it actually changes the quench speed over time.