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Canola oil....or Soybean oil???

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Just finishing up a three burner propane forge/oven that will take a three foot long part with it's 8" x 8" x 36" inside

dimensions. The present project is not a sword, but is quite similar in size to a broad sword, that is, 1/4" x 1 1/2" x 24"

5160 leaf spring for a small car that I'm building.  The material is new from Admiral Steel, an alloy steel supplier here

in Illinois, which I'm sure some have used for new blade steel. 

I'm just finishing the quench tank which is a 16 ga. 12" x 12" x 48" roll-about tank, which will hold between 15 or 20 gallons

of quench oil. 

I've been looking at the local Sam's Club and other stores for Canola oil and coming up with $30 to $40 prices plus the shipping

for 5 gallons, I found Soybean oil (frying oil) for about $16, which is more in line with my fixed income since I'm retired. 

The question I have is,,,,,will the Soybean oil give me the same result as the Canola oil?? It appears to be about the same 

consistency, so it seems logical that it would pull the heat away at about the same rate as the Canola oil. 

I believe, from what I've been reading, that the temperature I'm looking for is 1525° F to harden the material. Then

draw it back at somewhere between  400° and 600°. The temper temperature and time at temperature is yet to be determined.   . 

I'd appreciate any input from the group.. 


Denny Graham

Sandwich, IL 

48 inch Oil Quench Tank 01.JPG

Edited by Denny Graham
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5160 will harden fine in just about any oil, it's not picky that way.  Do warm the oil up a bit, just enough to be unpleasant to touch.  And yep, 1525 F is the ideal austenitizing temperature.  Depending on just how springy you want it, anywhere from 550-650 degrees F would be my guess.  575 is good for swords...

Too bad you don't have access to an austempering setup.  Heat the steel to 1550, dunk in 600 degree molten salt for an hour, let air cool.  That seems to be the industry standard for leaf springs, and apparently results in a hardness of 48-52 Rc.  So maybe temper yours at 600?  Sneak up on it from below.  You can always pull a hotter temper to make it springier, but if you so soft right off the bat you have to re-harden and start over.

Final thing: watch your forge atmosphere.  That a lot of burner for a small space, and with venturis that usually translates to oxidizing atmosphere.  That will cause material loss to oxidation (scale) and decarburization of the surface, depth and degree depending on how bad the atmosphere is and how long you leave it in there.  5160 does not need to soak at heat.  Get it there and quench.   If you are unable to get the atmosphere neutral by playing with the burner chokes, you can always toss a little wood in the forge every few minutes.  This can even give you a reducing atmosphere (which is good), but it can drop the temperature a lot at the start (not so good).  Just keep an eye on things.

And welcome aboard!

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Thanks Alan. Din't expect an answer so soon, appreciate your response and the tips. The burners I made

have pretty good dampers (threaded discs) so I can dial in a neutral or reducing flame quite easily.

I've got a long background in welding dating back to when I was a kid to modern day and I'm 75 now

in other words, I know a neutral flame when I see one having made a living a good part of my life

as a welder/machinist. 

(I don't know why I'm getting this dang double space in everything I type but............)

There isn't very much information about making your own leaf springs. Apparently the only ones that 

are privy to that are the "Spring manufacturers". I've been getting all, or at least 99% of my info on

heat treating 5160 from the blade forums like this one. But.....I needn't say, just about every member

has his own version of the heat treating process for their blades. 

Been watching  all I could find of the YouTube videos about commercial spring operations and all of them

I've seen bring the springs up to temp in ovens and lickety split, right into an oil quench, then to the

tempering oven. So...that's where I'm getting my process lessons from at this point.

I haven't been able to find any info on just how hard I need them to end up. I'll take your advice of 50 RC +/- 

a few points as a starting point. If I had access to a hardness tester I'd check a couple of the factory made leaf springs

I've got around the shop to see what they've been drawn back to.

Thanks again for the help.

Denny Graham

Sandwich, IL.




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Good to know you have the experience!  That's always an issue on online forums, we rarely know off the bat if someone is aware of the potential issues.  And yeah, most of the stuff you find on 5160 is how to make a high-performance differentially hardened blade, which is of little help with springs.  

I think it would be great if you could get a hardness number off a factory spring.  That would make it much easier to dial in the tempering heat needed.

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Been retired for 12 years but I may be able to talk on of the guys I worked with into taking a reading on a leaf off a trailer sprint I have on the shelf. 

I've got springs off me '50 Chevy truck but I'm almost positive they would not be 5160 alloy but they could still tell me where the leaf was tempered


Yep, there are a lot of guys that get on the forums who want to take up a new hobby but have never worked our in the shop. Pop was a blue collar welder

and tinkerer at home, so we boys were taught welding, machine work, mechanics and just about everything that you could get your hands into.

I've seen vids where the bladesmith took a heat treated blank and bent it close to 90 deg and it still came back. Not hoping for that much perfection

but I don't want to have a spring fail on me during a race.

Denny Graham

Sandwich, IL 


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Well, I picked up 18 gallons of pure Soybean oil at Sam's today. Putting paint on the rolling frame.

Slept on the suggestions of warming the tank. It's to large of a volume to heat up by dunking

heated scrap in before the quench, so......I picked up a heating element, controller and adapter 

at Menards this morning. Going to punch a hole in the tank side a few inches from the lower end

corner and weld four studs on before I paint it's outside.  

Hope this water heater 120 volt, 2000 watt element will do the trick. Made to heat 6 to 30 gallon

heaters. It tops out at 150°F, that should be good enough pre-heat for the oil don't cha think????

Denny Graham

Sandwich, IL



Quench Tank heating element & comtroler 01.JPG

Quench Tank on roller stand 01.JPG

Edited by Denny Graham
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Sounds like a plan.  You might need to stir up the tank a bit before quenching to get the oil all to the same temp.

I'd love to see the car you are building if you are going to this much effort just to make the leaf springs...


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This is the inspiration car Brian. It's a 1928 Riley Brooklands Monoposto Special

The one I'm building is a 3/4 scale Cyclekart replica of it, which is a form of small

car with motorcycle wheels using 200cc engines. It's a relatively new hobby that

is catching on out on the west coast. Hoping it will grow and spread east. Lots of

interest in them and we have several new members and builders sign on to the

Cyclekart forum every day from all parts of the world.

The heat treat setup, i.e., forge/oven, will be used for other projects also, but

for right now this is the driving force for it. It I can nail down the HT process

I may try to market a small number of special springs for these to help pay 

for the set up.

I've yet to heat treat any material, but would like to get going within a week

or two with some samples for testing spring rates and loads.  

Denny Graham

Sandwich, IL

Untitled-6 copy.jpg

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That will be a blast when you get it done Denny.  I'm familiar with some cycle car stuff being done with larger bike engines, but didn't know there was a growing movement using  200CC engines.

I have a friend in the midst of a low-cost 7 build, but he went the Miata engine route rather the bike engine.  His project has me salivating at times...


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One thing that I haven't talked much about is FIRE!!!!!!

Lot of caution about oil fires it on lots of forums. All of the 

Leaf spring videos that I've watched just show a flash as

the 5160 is dropped into the quench. The flame appear to 

extinguish with in a few seconds as soon as the initial vapors

are used up. Applying a little logic to it, if the quench volume is

large enough to pull the temp down within a few seconds then

no more oil vapor will be produced. The oil shouldn't get hot 

enough to sustain a flame. 

Does that sound reasonable?

I think it might be a good investment to add a CO2 extinguisher to 

the shop before I run this heat. Dry powder is cheap, but it would

make a real mess of things if I did have a mishap.

Denny Graham

Sandwich, IL

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A lid (in your case just a flat sheet of steel should work) would be good to have handy to smother the flame if needed.  But generally yeah, you should be fine.  The fire extinguisher on hand is ALWAYS a good idea though.  

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Got plenty of those dry chemical extinguishers Jerrod. Just about one in every room. They're fine in a

real emergency, but they make such a mess to clean up and can corrode what ever they cover. I worked

at a National Particle Accelerator for nearly thirty years and had fire training a couple times a year. 

That's why I'd like to get a CO2 bottle. They'er clean, but ya need to be careful around liquids as they

can splash it or blow it out of the container or puddle and make the fire worse.

Alan, I painted the base today but left the tank because I'm needing more welding on it. So......while

I've gone this far, I might as well add a hinged lid to it. I was going to use a 3/4 plywood lid to keep

the bugs and dust out when not in use. But it wouldn't be that much more to add an 18 or 20 ga. lid.

Just last week I was looking at some gas lid struts that were on sale super cheap. Gave them a pass

because I dint have an immediate use for them. Now, I can't remember where I saw them.


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On industrial tanks they use a lid spring-loaded to close when a pedal is stomped.  Easy and quick way to put out an oil fire without risking a burned hand.  And a lid biased toward closure will also keep the mice out.  They do like to go swimming in cooking oil...

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Had to spend the afternoon till dark mowing, so I dint get much done on the quench tank.

I did get a weld flange machined this morning so I'm ready to weld it in place and

mount the element. Got to figure out a mount for the contact thermostat, think

I'll go high with that. 

Now ya'll got me thinkin' about the lid. Have to figure that one out so that will put

me back another week.

Thanks for the input Alan.



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  • 4 weeks later...

Thanks guys, and thanks again for helping out an outsider with his non-cutting edge project.

I've got lots of other things planned for it, including some small forgings I want to make for the

Cyclekarts that I'm building and heat treating tooling for the shop.

Now......to fire and fill it all up and see how good of a "heat treater" I am.

Hope I don't burn down the barn!!!!!

Denny Graham

Sandwich, IL


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