Colour Case Hardening
After much research I’ve decided to give this a go…knowing that there are certain dangers. But, frankly, that’s why I’m in this game. I want to learn from others and pass on my own experiences both good and bad. First off, the kit list, for sure I needed a kiln/furnace of some sort and after a lot of research I ended up with a Kiln that could hold the container dimensions I needed and have an automatic timer.
As well as the kiln you’ll need a number of other parts and tools to complete the job. Importantly, you’ll need a canister to hold the parts that you are going to colour harden. I’ve fabricated one from steel. I’ll make one from stainless steel at some point in the near future as this is less likely to warp or cause problems over a longer period. As well as the canister I’ve made a removal fork (my terms but basically a tool to lift the canister from the kiln), quenching tank and a plate over the tank.
Here is the tank itself. It’s actually made from a cattle mineral container and I’ve overlaid some chicken wire. This has the simple effect of holding the metal parts whilst allowing the hot charcoal to call to the bottom. One can then simply lift the parts out easily afterwards.
The fork is made from a couple of threaded steel rods, these needed to be strong enough to lift out the canister and plop it straight onto the exit hole in the plate. I used a couple of bits of angle iron to create an easy to slot into parking place for the canister, remember, at this point it’s red hot! The canister is made of 150mm 6mm box. Quite heavy but also robust. It has a fabricated slide door at the bottom so that once in place you can release the entire contents into the quenching tank!
The kiln is made by a well know American company called Paragon and it has an automatic timer and controller where quite complex kiln routines can be created. A very cool piece of kit (in a manner of speaking of course). The canister fits nicely in there with some space, not a lot, around all the sides. Certainly it shouldn’t be touching the sides or elements within the kiln.
Well tomorrow I hope, with some help (I’ve recently had cancer which has resulted in my losing my right leg below the knee, but it hasn’t stopped me!) to try out the system. I’ve had one dry run and I’ll post the results, not perfect but a learning curve, tomorrow I hope to get it right. Thanks to Alex in the states for pointers too…and the numerous other sources of information.
Mate, can you give me an indication of what temps and times are req`d. to do this
Cheers
Hi, For annealing I heat the parts for 1 hr at 825 Deg C. Then let the kiln with the parts cool overnight without taking the parts out. For the CCH I heat the kiln to 723 Degrees C and heat for 1hr…then after 1hr 15 mins I take the canister out and quench into VERY cold water with no oxygen gap. Hope this helps. Cheers Tony
Hi Tony…
Doug here, been reading your CCH journey’s here on your site…..How do you like the new Paragon kit you bought….?………..
Very nice to see your operation and ideas here….I like the construction of your canister, we call it crucible here in the states…..Did you make it or was it part of the kit you speak of…?..
Doug
PA24
Hey Doug, good to see you!
The Paragon is just perfect…timer is great and I’ve already used two programmes. The canister is home made from 150mm/6mm box with ends and a sliding door one end!
Cheers
T
Sounds really neat Tony…………..CCH sure is a lot of fun, all kinds of neat things you can do………!……………
Canister looks super nice………My furnace is a front loader that I got from Brownells years ago, but works fine…..a little bigger maybe….has an auto timer as well……..
Looks like you are doing about 1350 F…725 C….which is perfect I believe…..some people do 14-1450 F, but I personally think that is on the high side…….I do believe the factories originally did 1500 F or so…..?…..Nobody actually knows though, because they treated their process like a ‘black art’ or ‘witchcraft’………
The Paragon is a ceramic kiln….?………..Thanks and Best Regards Always,
Cheers there Mate,
Doug——
Tony….
PeteM is the guy on DGJBBS who can probably provide you with the link for those pictures from the 1922 Marlin factory in New Haven, Connecticut…..
I am sure he pulled them from the internet somewhere….
Best,
Doug…….
Tony,
Have you tried sealing your crucible with “Pyruma” this has the effect of keeping the contents uncontaminated during the firing proccess,the seal breaks easily when quenching takes place.
C.M.B.
France.
Hi Chris, what’s Pyruma!
Sounds interesting.
Tony,
Pyruma is a fire cement/clay, with which we seal firebricks in domestic stoves,it is sofened by mixing water,or keeping damp in the container(I useually keep a damp rag on top of the Pyruma inside the tub)It can be odtained from any good fireplace store.When I worked at a college in UK we used to seal the crucible when carburizing(case hardening)students work,this came out of the quench without colour as it passed through air when tipped from the crucible,but we were after hardnes not colour,(we were also trying to conserve out carbon)the theory is that there should be as little exposure to atmosphere as possible,and some dump crucible and contents straight from the furnace into the oxygenated cold water.There is an excellent article by Prof Alexanda Johnson of South Dakota which covers the whole proccess in great detail,it covers blocking,water temp,carbon types/mixes and furnace temps.I think it is even better than the Oscar Gaddy paper.
Regards,
CMB.
France.
Nice tip Chris,will look into this.
Chris do you have that article I’d love to read it…
Cheers
T
Tony,
Only to glad to pass on what details I have,the paper also covers a post hardening tempering proccess at 450 Deg F to enhance the colours,although at that temperature it may effect the hardness! How can I get the paper to you? It runs to 20 pages
Chris,
France.
Hi Chris, email sent…many thanks