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Old 04-17-2010, 01:30 AM
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Default Case hardening.... take one

In another thread I asked for help with a lathe chuck runout.
In the process of getting that sorted I discovered that the cam locks were mild steel and burred/scored.

So I could get a solid lock with the cams I first tried to get new ones with no luck. Commercial case hardening is spendy, so I am doing it myself. ( I hope )

I cleaned up the burrs and scores from all three cams and gave a modest polish to all. On one of them I left a small burr to file off later so I could get an idea of how hard they had become. ( pic 1 )

I lit the forge and got a deep bed of coals going with an overhang at the back. If it worked properly the cams would soak in the heat, under the overhang, with little oxygen present to create scale.
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Old 04-17-2010, 01:35 AM
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Some more pics of the process

The cams in the fire with flash on and off. Sorta lost some detail both ways so I did both.

The cam just before going into the charcoal pack

All three cams in the tin before being covered with more charcoal.

Now I wait till tomorrow and see what happened. If it failed then I will just reheat and try again, probably with a longer heat by putting the tin in the fire to keep it hot for as long as possible.
Hopefully I wont need to do that.
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Old 04-17-2010, 01:49 AM
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Good luck, AJ. I sure hope this works for you.
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Old 04-17-2010, 02:25 AM
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I know absolutely nothing about hardening so excuse my ignorance....don't you have to put them in some sort of liquid to harden them? (i thought i heard this once)
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Old 04-17-2010, 06:47 AM
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You would use an oil or water quench on carbon steel.
Mild steel wont harden due to the very low or non-existant carbon content.

The case hardening process allows enough carbon to get into the metal surface to create a harder shell. The longer it has to be in contact with the carbon source, the deeper the case.

The unknown part is I havent done this before so it is all 'try and see'.

Thanks Cutter. I will find out in the morning.
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Old 04-17-2010, 06:54 AM
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Quote:
Originally Posted by AJinNZ View Post
The unknown part is I havent done this before so it is all 'try and see'.
This is the essence of learning coupled with listening. We will wait and see which is what this sight is about. Thanks for sharing AJ.
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Old 04-17-2010, 09:06 AM
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From all I've read, charcoal pack hardening requires a sealed container and a relatively long heating period. The charcoal produces carbon monoxide under those conditions. That then diffuses into the metal where the CO can react with the iron, producing CO2 and releasing some carbon. The process takes quite a bit of time depending on the depth of hardening required - hours and hours.

Don't know if you can access this book:

http://books.google.com/books?id=Xh8NAAAAYAAJ&pg=PA562

If you can get some Kasenit hardening compound you'd save a lot of time and trouble. It's primarily Sodium ferrocyanide (yellow prussiate of soda).
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Old 04-17-2010, 09:42 AM
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The studs don't need to be hard. See where the cams are binding and relieve that area with a stone and die grinder.

If you really want to harden them, which apparently you do, get some casenite. It will do the job.

http://flagstaffpermaculture.ning.co...dium-caseinate
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Old 04-17-2010, 06:32 PM
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I put the cams into a tin with a lid, so hopefully the seal will be adequate.

If the length of time in there was not enough then I might have to use the kiln to maintain a much longer hot phase.

I tired to get kasenit, but it is unavailable here and the only other compound I can get ( called 'quick hard' ) is 70 bucks per pound. I decided to pass on that one......

The cams were not binding. As they reached a full lock on the chuck studs, instead of just pulling up tight they scored and burred over due to the studs being harder and the cams being soft as butter.
I could clean them up and end up in the same boat after swapping the first chuck.

I dont need full on HARD for the cams, just enough that they work as a cam and not get ripped up in the process. These really were soft as butter.
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Old 04-17-2010, 11:58 PM
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I really hope this works for you. Jerry
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