i'm from Birmingham but now live in Bromsgrove, I worked for F.W. Leesons in 1968 doing
clock repairs but now only repair them for friends and family.
Looking forward to reading more on this forum.
I probably wouldn't case harden a part like that, easier to grab a piece of tool steel, heat and quench. Because the centre is still ductile, case hardened parts are not usually tempered and you don't want dead hard threads, they're brittle. I'd probably make it from a steel that could be through hardened. Where it shines is when you want parts with a dead surface bu still have the flexibility of a ductile centre
As for recipes etc, I have enough knowledge to understand the application insofar as use and design goes, but I've always sent parts out to commercial heat treaters for case hardening.....so don't often do so unless there is some specific advantage to casehardened the part.
Lots of info out there for you uncover, I'm just not the guru on specific pack hardening recipes. Bone meal is one, but I understand it stinks something fierce so would be better done outdoors. That, and you need a away to hold the steel above the critical temp during the soak
There is a quick and dirty approach, but you'll only get a few thou or so depth with a couple treatments. You get the piece red hot with a propane torch and roll the piece around in Kasenit. It does work for wear, but its not very deep. I have done that method many times. Kasenit isn't made anymore, but I understand there's a replacement.
Just for interest, here's some model hit and miss engine parts I did a Kasenit case hardening on
OK. Suppose I have a dia. 6mm x 50mm shaft, cut and threaded that I want to case harden entirely, do you have a practical recipe, step by step and with all the times, materials and tools? I don't care which color it takes as I assume I can blacked it with a "magic" liquid. l also want to get a booklet about this, but if it doesn't it has the.approach above it will be useless to me.
There are many ways, the basic theory is you expose the material to carbon for a length of time over the critical temperature and the carbon "soaks" into the material. Enough so that when quenched, the carbon % is high enough on that outer layer to harden. This works with pretty much any mild steel. Depth of the case is proportional to the soak time - it maxes out at about 0.050" with a 24 hour soak. Its not so much a replacement for tool steel, but rather offers different advantages; steel is cheaper, core is still ductile, you can block the carbon from getting to some areas so control what is hardened and what is not.
Most techniques involve some nasties, cyanide salt bathes etc best left to commercial shops. However beautiful work can be done in the home shop via pack case hardening - literally packing the work in say bone meal in a sealed container then holding it at heat for the required length of time (depends on depth wanted). This produces the fancy colours, like the gunsmiths strive for or Starrett used to put on tools.