Case Hardening Help!

[Mike Ginn]

I have a need to case harden the rocker arms of the Kiwi and I am seeking advice on the "best" process.

I have a good supply of propane but I do not have a furnace - just fire bricks. The parts are about 35mm x 7mm x 7mm and machined from bright "mild steel" bar. I don't have the steel ident.

I have looked on Youtube and the advice ranges from furnaces with temperature equipment to dipping the parts into Kasnet - which I have but am concerned about its safety.

What is the easiest and simplest method of case hardening very small parts

Many thanks in advance

Mike

 

[Jasonb]

I just use the torch to heat them to a bright red and then poke them into the powder before they have a chance to cool. Remove from powder and heat again then quench. I us ethe "beta" powder that several of the ME suppliers sell

If you are using the old Kasenite then just avoid any fumes and dust.

 

[SmithDoor]

Kasenite works the best that have found.

I read in old books use coke or charcoal and salt (not table salt I do not remember the nane).
You pack it and cook in a charcoal or coke over night would do good job.

Dave

 

[Sprocket]

I’ve used “Cherry Red” with good results. Same process as Kasenit, (as Jason described) seems more available. I use oxy/acetylene for heat,
but if you can get red heat , the source doesn’t matter.
I don’t recall about toxicity, I just do it
outdoors.
Doug

 

[Joe]

I have a need to case harden the rocker arms of the Kiwi and I am seeking advice on the "best" process.

I have a good supply of propane but I do not have a furnace - just fire bricks. The parts are about 35mm x 7mm x 7mm and machined from bright "mild steel" bar. I don't have the steel ident.

I have looked on Youtube and the advice ranges from furnaces with temperature equipment to dipping the parts into Kasnet - which I have but am concerned about its safety.

What is the easiest and simplest method of case hardening very small parts

Many thanks in advance

Mike

John

 

[colby15642]

I have a need to case harden the rocker arms of the Kiwi and I am seeking advice on the "best" process.

I have a good supply of propane but I do not have a furnace - just fire bricks. The parts are about 35mm x 7mm x 7mm and machined from bright "mild steel" bar. I don't have the steel ident.

I have looked on Youtube and the advice ranges from furnaces with temperature equipment to dipping the parts into Kasnet - which I have but am concerned about its safety.

What is the easiest and simplest method of case hardening very small parts

Many thanks in advance

Mike

I have used Kasenit No. 1 for 60 years with no ill health effects. You can find a lot of information online about its contents, which does include a food-grade cyanide anion. That is not the same compound as the classic poison cyanide. Kasenit products are reportedly not available in all countries and now maybe not at all. Cherry Red is another brand of similar-performing material. An eBay seller claims to sell a generic equivalent, which could be grtound bone meal which is high in carbon content.

https://piehtoolco.com/contents/en-us/p10932_Cherry_Red_Hardening_Compound.html

 

[Steamchick]

In the 1960s, we wrapped steel in leather - completely to exclude air - then dropped in the burning red coals of a wood fire - or coke, or coal, - so the high carbon (charcoal) burned the leather away while the steel got red hot. The result was a good case hardening, so ordinary files and drills didn't want to cut the steel. We didn't have means of testing the thickness of the case. PArts were quenched after removal from the fire after an hour or so. We also used Kasenite - with a blow-lamp heating one end of a piece of steel rod, repeatedly dipping in the Kasenite and heating again to burn it off.
Similarly, when nothing else available, my Dad used sugar - seemed to work just as well after several dips-and-burn cycles.
I also was told that high nitrogen fertiliser works similarly to Nitride harden steel. No idea how effective, but medieval blacksmiths used a strong solution of urine to quench swords to get a harder edge on them.
And I struggled to drill some mild steel brackets after brazing onto steel tube using an electric carbon arc torch on my weld set. Well case hardened! But once through the case hardening the mild steel drilled normally. I used cobalt steel centre drills to break through the hard case.
Steel (wire) piston rings are nitride by cooking for an hour or more in an oven full of burning ammonia gas. Do not try this at home!
The barbecue makes a very good high carbon fire, make it big, to ensure no oxygen burns the steel, keep fuelling while the parts cook in the coals for an hour and that should give them a hard case... Repeatedly remove and dip in sugar or a case hardening powder, and finally quench. Test a spare piece of material in with the proper parts, with a file, and compare to original un-hardened metal. You should easily feel when hardened.
K2

 

[Mike Ginn]

Guys - thanks for your help and I will now "have-a-go" as they say. I will however give the urine process a miss as I am unclear what "a strong" solution means - maybe after a session at the local pub!

Thanks again

Mike

 

[TimTaylor]

If you have a small piece or two of scrap from what they were machined from, I'd try that first before risking the machined parts.

Kasenit specs say it can harden up to 0.020" depth if you follow their process.

 

[Mike Ginn]

You know Tim - thats an obvious thing to do BUT I hadn't thought of it.

Many thanks

Mike

 

[Steamchick]

Strong stuff (P) is after lots of protein and vegetables... not a lot to drink. Like strong tea, not weak beer in colour. Lots of Nitrogenous waste (yellow dye).
A guy who uses it on his compost heap - I was taught that as a kid - saves all his strong stuff. Used to be common a cleaning fluid...
K2

 

[TimTaylor]

Strong stuff (P) is after lots of protein and vegetables... not a lot to drink. Like strong tea, not weak beer in colour. Lots of Nitrogenous waste (yellow dye).
A guy who uses it on his compost heap - I was taught that as a kid - saves all his strong stuff. Used to be common a cleaning fluid...
K2

Also touted in an urban legend for dissolving sea urchin spines - reality is that white vinegar works better...

 

[Mike Ginn]

I suppose you could reduce the urine in a saucepan on the kitchen hob but you would need a good air extractor and probably be living alone with no neighbours!

I think I will give it a miss and who needs a smelly compost heap. Beata 1 is the way forward for my small parts.

Mike

 

[ChazzC]

Also touted in an urban legend for dissolving sea urchin spines - reality is that white vinegar works better...

As it is sterile (from a disease-free individual and as it leaves the body), legend says you can use it to clean wounds.

 

[TimTaylor]

As it is sterile (from a disease-free individual and as it leaves the body), legend says you can use it to clean wounds.

Another myth or urban legend. Urine, even in a healthy individual, is not sterile. It contains an assortment of bacteria.

 

[SmithDoor]

I have a need to case harden the rocker arms of the Kiwi and I am seeking advice on the "best" process.

I have a good supply of propane but I do not have a furnace - just fire bricks. The parts are about 35mm x 7mm x 7mm and machined from bright "mild steel" bar. I don't have the steel ident.

I have looked on Youtube and the advice ranges from furnaces with temperature equipment to dipping the parts into Kasnet - which I have but am concerned about its safety.

What is the easiest and simplest method of case hardening very small parts

Many thanks in advance

Mike

Remember a good charcoal in hole in ground will job or old BBQ. They both work and have used propane but I built a furnace for propane.
Do not use charcoal like Kingsford you the old fashion lup charcoal like restaurants use.

(I have read on the internet using a nitrogen fertilizer mix the coke or charcoal mix inside a steel pipe with part. I do not know how will this work or just someone writing internet junk. )

Dave

 

[TimTaylor]

For anyone interested in the chemistry of various surface hardening processes, this link has a really good basic explanation.
https://en.wikipedia.org/wiki/Case-hardening

 

[Ken I]

Allied POW's during WWII would make bolt/wire cutters from mild steel brackets off their huts.

They case hardened them by heating slightly - then dipped it in sugar to form a high carbon coating - then buried in the heating oven's coals to soak.

Thereafter quenching and tempering as per normal practice.

A "sugar tax" was levied on all supplies of this precious substance.

FYI

Regards, Ken I

 

[bluejets]

I have a need to case harden the rocker arms of the Kiwi and I am seeking advice on the "best" process.

Use a piece of silver steel ( drill rod) it will water harden after heating....simple.

 

[awake]

Use a piece of silver steel ( drill rod) it will water harden after heating....simple.

Simple indeed ... but sometimes a case-hardened part is preferable to a through-hardened part such as will result from hardening silver steel. That said, I'm guessing the difference will not matter much in a model engine - ?