What size dovetail cutter? Mitutoyo test indicator

Janderso said:
I’m ok with it. I didn’t do my homework as I should have.
The next time I do this I’ll have a much better outcome.
I learned quite a bit on this project.
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That is the correct attitude. Good for you. We will be eagerly awaiting the new improved version.


Cutting oil is my blood.
 
mattthemuppet2 said:
Why do you need to harden the parts?
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Good question.
So the finish is more durable.
I also have an interest in doing more heat treating. This gives me twice the experience. :)
Next time, I won’t screw it up!
 
Would a case hardening be more appropriate than through-hardening for a part like that? Then you could cool it slowly in the furnace overnight instead of quenching. Good excuse to try case coloring!
 
Pontiac, I was going to suggest the same thing. Though to be truthful of imagine most measuring gear like this in a home shop would probably be fine as is.

Janderso, of you want to get some practice hardening stuff I'd start off with some simpler parts. The very different cross sections in that part are going to hear and cool at different rates = cracking. An alternative would be to do a slow ramp up, soak and slow ramp down before quenching
 
Janderso said:
I learned another lesson today. I was quenching this part in oil, the container was not quite big enough meaning it didn’t hold enough oil to stay cool enough throughout the process. I thought I would just finish off the cool down in my little stream.
I heard a cracking sound.
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I feel your pain! That sucks.

So, you're running A2? Do you even need to quench in oil? A = Air Quench. I'd set it on a wire mesh stand and let 're cool in still air. If that doesn't get it, try an air blow gun on the thick parts.

The only time I've had a sample crack, was a test sample for a buddy. He had annealed some jeep axles, machined them for a different application, and we heat treated them. We did a test sample slug first, and and tried water which was too fast (cracked) (And Veg oil, too slow). After that we bought a pail of quench oil from McMaster and made a proper quench tank. That was probably 1045 or 1050 steel, usually needs fast quench, but water was too fast with that cross section.

The other trick, we bought an old kitchen range, and used that for a temper oven. Parts went right into the temper oven after quench. Didn't let them cool much below the quench oil. Preheated the oil to ~125F. It picked up some temp during quench, due to the part being large. We could only do one axle per evening, due to oven size and quench tank size.

Edit: He beat the living daylights out of those axles, and they never broke again. That's my only feedback on the quality of the HT, BTW.

(Also replying to subscribe, I'm in the process of collecting ideas for making something similar. I thought about plain carbon, and maybe surface hardening them...)
 
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