What is done if the parts warp? Anneal them, straighten and try again?

Logan wrote on Jan 7^th, 2026 at 10:20am:


I think if parts warp the person doing the case hardening did something wrong. Guys who've done it for years know how to without warping parts.

If parts warp,,and they do inspite of what the purveyors will say,,
Many can be 'straightened'
by simple but well educated strikes with a lead hammer.
Most of the parts can be straighten.

Marlin used a small 'jack' to open up the bolt slot on L/A's.
A simple tool that just worked as a nut unscrewing the bolt can be used to do the same. 
A wedge and hammer can be used as well.
My experience is with the former

Some heavy or very fragile parts will need to be annealed and then re-worked back to straight. Doesn't always work out.

It is a far less common issue today than it was 30+ yrs ago when some started seriously doing CCH.
But we did more than I like to remember!

Much better understanding and control these days for sure.

2152hq and steel-pounder,

Fantastic information, can a case hardened part be rust blued? I would think the hardened steel would be resistant to rust, making this difficult.

Logan

Ahh ok, thanks Vall. So the factory would case harden everything then rust blue the parts they wanted? Just for the aesthetic appeal?

Logan

I found in the Lassen Color Casehardening class that the difference between color casehardening and just plain casehardening was merely letting the least little amount of air get to the parts between being dumped out of the charcoal packed crucible and hitting the quench water.

Timing was critical.  We had to pick the retort out of the oven with long tongs, and hold it with the tongs while someone else with their own tongs lifted off the lid.  You could see the remains of the scrap of paper we put in the top to take up the oxygen burst into flame at this point, and of course the charcoal surface starting to glow (and nothing had better be sticking out of it, either).  As soon as the lid was off, we swung the crucible overhead like that carnival midway bell-ringing setup and banged it, open end down, hard against the lid of the quench tank so the contents, still shielded by the charcoal packing, all came out in one mass and quickly slid through the hole in the top into the aerated icewater.

There would be a huge eruption of blackened steamy water and a chorus of "Ooohs" and "Ahhhs" from the appreciative crowd of students waiting to get their own crucibles out.

I had a rather elaborate hooked buttplate that stuck in the crucible and took a couple extra "bangs" to shake it out.  It came out of the quench as hard as the other parts but a uniform black color.  I'd gotten a similar black when rust bluing parts until I modified the Neidner formula with my special secret alchemy.

Logan,

No; I left it black.  still haven't attached it to a stock.

It would have required repolishing, reannealing and another packing in the crucible.  It was one of those Germanic types with the big lower hook and the hole at the apex for an acorn screw.  Got a little crossways in the crucible so the end of the hook and the top jammed against the sides.

It was just another part to take up room in a short crucible load.  By then we were running out of charcoal so I didn't want to waste any just to take up space.  We'd also raided the ice machine at the cafeteria so much that there was none left that afternoon.  Fortunately, it was summer and few students were there to eat.