Posted by BillS on March 18, 2008 at 12:35:56:
In Reply to: flame hardening gear or sprocket teeth posted by steve Green on March 17, 2008 at 13:07:46:
Well, this is gonna be as "black-smithy" as you can imagine...
Way back when we used to put a rod over a five gallon bucket with the gear on the rod. We put a hose in the bucket and let water trickle into it. (The level was controlled by a hole in the bucket an inch or so below the top just to keep the guys feet dry!). An acetylene torch was used to heat a tooth or two cherry red just above the water, and the gear was constantly and slowly rotated into the water to quench. Don't try to heat the tooth too quickly - you don't want to melt em!.
We made the gears from c1144 hot rolled and this seemed to work well enough (sulpher stringers aside!). You have to use a medium carbon steel; too high and the teeth could easily be brittle. C1144 would usually be around 45-50 Rc as I remember, and never as much as 60 Rc. Of course, warpage can be a problem.
Something to experiment with if you need to do a few.
I'll bet there are some other more ingenious methods, right guys?
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