Final Drive Sprocket - Heat Treatment

And there are plenty of cases where people discovered the same thing at close to the same time in different locations around the world. One great thing about our current predicament is how suddenly the Scientists are leading the Pollys and they are accepting this without the usual stupidity. I guess the death tole got that message through. It would be one horrible world with Antibiotics that's for sure. Another good thing is way more research is now being funded for all this stuff. O Dear I have gone to THAT again. Science is good for us all.
 
Piranha Brother 2 said:
:LOL: :LOL: :LOL:

I reckon we could ask that question of many 'inventions' and scientific techniques of old. Herbal medicine is a good example -  how many patients died refining this herbal hemlock remedy?  :o :D
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Not as many as sly grog distillers. A bloke I work with measured his last batch at 93%. A glass of that, and you?d be chatting to your great great grandfather.
 
ngiles said:
What I always end up wondering is how on earth they figured this out, as they stood staring at a piece of iron bemoaning the softness of the metal, and someone suggests packing it in leather, hooves and salt - oh and while we're at it, lets piss on it too - I reckon that'll do it....
Just wondering  :D
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:LOL: My favourite is how did anyone come up with the idea that adding fish guts (isinglass) to beer would make it crystal clear?
 
ngiles said:
Apparently, according to wikipedia, case hardening was traditionally done by "packing the iron in a mixture of ground bone and charcoal or a combination of leather, hooves, salt and urine, all inside a well-sealed box" so the urine theory sounds real. 
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The whole thing would then have been heated up, perhaps by chucking it in a fire. The organic matter would turn to carbon, some of which would infuse into the surface metal along with the nitrogen from the urine. So you increase the carbon content of the surface layer as well as nitriding it. I dunno what the purpose of the salt is.

CLEMTOG said:
urine is quite close to being salt water
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Salt water doesn't have nitrogen in it.
 
Antibiotics are on the downslide!
Bacteria have developed a natural resistance to many types of antibiotics, so unless pharmaceutical companies continuously develop new versions  then they won't help much.
The future of medicine seems to be in the field of genetics.

Case hardening was no doubt a happy accident. I case hardened a stud extractor I made by heating to cherry red, dipping in carbon powder and then quenching in oil. I think from memory I had to do it a few times to get a deep hard layer.
 
The manager of my local engineering workshop taught me a neat trick for surface hardening of mild steel.

Fire up an oxy torch but don't turn the oxygen on, so you have a yellow acetylene flame only. Play that flame over the area you want to harden until you have a nice black layer of soot.
Turn on the oxygen and heat up the piece with a normal flame until it's dark red (the soot all disappears).
Do that process a few times and you end up with a hard layer on the surface. Some of the carbon from the soot diffuses into the surface layer of the steel. On the final heating, quench the piece in whatever quench medium you prefer - oil, water, piss, Dom Perignon ...

I had my doubts when he told me, but I tried it and it does work.
 
I dunno Quentin, but I'd guess not.

I suspect the advantage of sooting up the surface of the steel is that you get an even application of the carbon exactly where you need it - in contact with the surface.

Just chucking something in a fire isn't going to give reliable surface contact.
 
Hi Cam, my old man told me about using the acetylene flame to lay a surface of carbon on the metal before hardening. That's only the second time I have heard that from anyone else.
He'd studied engineering, metallurgy and welding during his working career. He could put a bit of metal on the grinder and from the sparks could tell the carbon content and make up of the steel. But then again I was young and he could've been bullshitting me!! He was a clever man when it came to metal though.
 
Heres another one, I was at a mates place and one of his flatmates was doing up a V8 Commodore. He was doing something called blackening the bolts, its a corrosion resistance thing involving heat and quenching. I don't remember the details though. It put a black finish on std steel bolts so they didnt rust.
 
Bolt blackening is done by heating the bolt up and dropping it in oil. Used engine oil is best because it's pretty black to start with. Heat to a bit less than red hot (until it starts to go blue) and drop it in the oil. You don't want to get it red hot or it'll bugger up the heat treatment of the bolt. It just needs to be hot enough for the oil to burn onto the surface.

Here's a video (not a bolt, but the process is the same): 

 
Dellortoman said:
Bolt blackening is done by heating the bolt up and dropping it in oil. Used engine oil is best because it's pretty black to start with. Heat to a bit less than red hot (until it starts to go blue) and drop it in the oil. You don't want to get it red hot or it'll bugger up the heat treatment of the bolt. It just needs to be hot enough for the oil to burn onto the surface.

Here's a video (not a bolt, but the process is the same): 

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Interesting. I was sure I had heard of that years ago, so when I changed the oil cooler hoses on the Jota 7 or 8 years ago I thought I'd try it on the fittings. They were a bit rusty and I didn't want to send them away for plating (and wasn't fussed on needing them shiny) so heated them up and quenched in old oil.
Didn't work as well as I'd hoped although finish looked quite good originally.
Think I needed to get them a bit hotter so might just try that again..........
 
At Tech School, I had to make a tapwrench. When finished it was heated up and dropped in oil engine oil. Is till my go to tap wrench. Stayed black for years, until I moved to the sub tropics. Time an humidity has taken its toll, but, it still screws in and out like the day it was quenched.
 
motoddrob said:
Hi Cam, my old man told me about using the acetylene flame to lay a surface of carbon on the metal before hardening. That's only the second time I have heard that from anyone else.
He'd studied engineering, metallurgy and welding during his working career. He could put a bit of metal on the grinder and from the sparks could tell the carbon content and make up of the steel. But then again I was young and he could've been bullshitting me!! He was a clever man when it came to metal though.
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No bullshit, Rob.

Different steel alloys will throw different types of sparks upon grinding.  You do need a keen eye to differentiate though.

The metalworking handbook that accompanied me through my formal training has a nice colour page showing several types and colours of sparks from different alloy steels.  Strangely, a (much) later edition of the same handbook no longer shows that particular table!  Seems this will be information only oldtimers know about...

piet
 
I made 1 and a half sets of V blocks during my apprentice days.

The half set came about because the shop leader walked past as I was surface grinding. He noticed the sparks were 'wrong' (I can't remember his detailed advice) and told me to start again as I had selected the wrong stock. I didn't mind as I found the previous shaping machine stage strangely hypnotic and was happy to do it again 😀

I still have the blocks.
 
There is something in the memory about the grinding wheel used for Tungsten Tipped wood saw blades being different to non tipped blades. There was a coloured spark thing in that case as well I think.
 
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