What size dovetail cutter? Mitutoyo test indicator

pontiac428 said:
If that's the case, you need to use U- series tool steel. A- and O- might crack under the quench stream.

View attachment 434752
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Take a look at this pic.
If I heat this to the suggested 1,450 with a proper soak, dip it in 100 degree oil in and out them let it set in the oil, would it crack? It’s O1.
Maybe I don’t need to heat treat it, maybe I can air cool it.
I’m afraid it will crack with the thin material at this feature.
The fit is perfect.
There is no substitute for experience. I’m slowly gathering it, the hard way.
 

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dkemppai said:
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...)
Click to expand...
Good to know.
The only A2 is the small piece that holds the indicator. The two that cracked were O1. My fault, way too cold, too fast.
I got in a hurry. Stupid, stupid!!!
 
Janderso said:
I have no experience with U?
Click to expand...
Awww, my picture didn't show up. That explains everything!

A=air, W=water, O-oil, and U= (your little stream).
images.jpg
(I hope the picture works, even if it's not helpful.)


But jokes aside, the part you are working on looks very tricky with the thick and thin sections. I wonder if it rings like a tuning fork when struck. I think case coloring is the hot ticket for a sweet shop-made precision tool. That will give it a hard surface, so it won't wear out, so it should accomplish the mission. And it looks so nice! Color case is an embellishment that disappeared with war production and never came back... until now?
 
pontiac428 said:
Awww, my picture didn't show up. That explains everything!

A=air, W=water, O-oil, and U= (your little stream).
View attachment 434778
(I hope the picture works, even if it's not helpful.)


But jokes aside, the part you are working on looks very tricky with the thick and thin sections. I wonder if it rings like a tuning fork when struck. I think case coloring is the hot ticket for a sweet shop-made precision tool. That will give it a hard surface, so it won't wear out, so it should accomplish the mission. And it looks so nice! Color case is an embellishment that disappeared with war production and never came back... until now?
Click to expand...
Ok, how the heck do I do that?
I love the idea.
Cyanide?
Case hardening approach?
 
Janderso said:
Good to know.
The only A2 is the small piece that holds the indicator. The two that cracked were O1. My fault, way too cold, too fast.
I got in a hurry. Stupid, stupid!!!
Click to expand...

If you're quenching big chunks of O1, you might want a commercial 'slow' quench oil. You could try veg oil. It's cheap, but stinks when it burns. It would be easy enough to make a mock up and give it a try. I've been heat treating in the home shop for close to 20 years, but honestly most of that has been thin stuff like knife blades and similar small parts. Don't usually do a lot of big pieces.

Oooh, I forgot. I have a whole pile of 416 stainless blanchard ground .880 thick by two inches wide... ...hmmm now you have me thinking... ...I could ship you a few chunks if you wanted to make two sets of parts... ;)

Have a bottle of Minimox I've been meaning to try out on it too...
 
For color case you can use bone charcoal that's literally smoldered bone. You can make it in a coffee can out of bones from rib night. But from what I've seen on the net and in books, the way to get bright blues and golds is to use Kasenit or that red hot or whatever it's called from Amazon. I don't remember the name, but it'll pop right up on a search. There are a few ways to do it, but the books again say bagging the part with the bone/Kasenit/cyanide in stainless foil and crimping the edges to keep oxygen from getting in and then putting it in the heat treat furnace is what works best. It's a temperature cycle and a nitride/cyanide/carbide case hardening, not a heat and quench, so it shouldn't warp or break parts that are ground to final dimension and finish. I haven't done it, I just think it's neat and would like to try someday. I have some .001 precision thickness stainless steel foil, made in Germany... it's good stuff, from dental... I could send you a few feet with a postage stamp if you want to give it a go. Or you could make a hat with it, up to you. I won't judge.
 
dkemppai said:
If you're quenching big chunks of O1, you might want a commercial 'slow' quench oil. You could try veg oil. It's cheap, but stinks when it burns. It would be easy enough to make a mock up and give it a try. I've been heat treating in the home shop for close to 20 years, but honestly most of that has been thin stuff like knife blades and similar small parts. Don't usually do a lot of big pieces.

Oooh, I forgot. I have a whole pile of 416 stainless blanchard ground .880 thick by two inches wide... ...hmmm now you have me thinking... ...I could ship you a few chunks if you wanted to make two sets of parts... ;)

Have a bottle of Minimox I've been meaning to try out on it too...
Click to expand...
Vegetable oil, hugh. Never thought of it. Works ok?
I may send you a pm on the steel.
Thanks
 
pontiac428 said:
For color case you can use bone charcoal that's literally smoldered bone. You can make it in a coffee can out of bones from rib night. But from what I've seen on the net and in books, the way to get bright blues and golds is to use Kasenit or that red hot or whatever it's called from Amazon. I don't remember the name, but it'll pop right up on a search. There are a few ways to do it, but the books again say bagging the part with the bone/Kasenit/cyanide in stainless foil and crimping the edges to keep oxygen from getting in and then putting it in the heat treat furnace is what works best. It's a temperature cycle and a nitride/cyanide/carbide case hardening, not a heat and quench, so it shouldn't warp or break parts that are ground to final dimension and finish. I haven't done it, I just think it's neat and would like to try someday. I have some .001 precision thickness stainless steel foil, made in Germany... it's good stuff, from dental... I could send you a few feet with a postage stamp if you want to give it a go. Or you could make a hat with it, up to you. I won't judge.
Click to expand...
Thanks John,
I have the foil. I’ll check the web for kasenit, or substitute. I bet Brownell’s has something.
 
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