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a word for oven tempering


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#1 FieryFurnace

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Posted 18 January 2010 - 06:37 PM

I've been blacksmithing for something like four years now and have only been messing around with carbon steel for the last year. I still don't know anything about it, as I don't have a teacher and so no hands on pro-experiance. However, I have made a variety of tools this summer using oven tempering. I've made 2 hole punches, 2 eye, punches, 2 knives, a cold center punch, and I'm working on 2 chisels now. (One flat one curved face.) I usually forge, anneal twice (if grinding,) quench at critical, and then oven temper at 2-350 degrees. I don't know if this is correct procediure or not, but I will say this much. None of my tools have cracked or chipped and my blades hold a good edge. I've done this with sucker rod and leaf springs and it seems to work. Even the center punch (sucker rod) has withstood about 20 blows (cold in 1/8 to 1/4 bar and plate) and is still holding it's point undaunted. So if you are a newbie when it comes to carbon, I would not be afraid to make some quick get-by tools this way. That is get-by until you can get with a pro and learn better method.

I'm sure you pro guys might have a word to stick in too, so if this is in eror, or another step would increase function, post corrections.

I know though, when I was starting out, I was afraid to work with carbon just because I had no idea how to do all of the steps right. However, like I said, these tools that I am making now only take a couple hours and last quite well. I wish I had known how to do this when I was first starting, because it would have made a lot more stuff possible and it would have made a lot of stuff easier!

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#2 dablacksmith

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Posted 19 January 2010 - 09:32 AM

that is why when i teach blacksmithing one of the first things i teach is hardening and tempering! makeing your own tools is one of the things that set blacksmiths apart from some other trades! with suffecient experience a blacksmith can make almost all of his own tools .. I agree you shouldnt be aftaid to make items from spring steel if properly tempered they are usually better than the factory made tools.have fun!

#3 mike-hr

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Posted 20 January 2010 - 12:54 AM

What are you quenching in? Air, oil, water...
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#4 ThomasPowers

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Posted 20 January 2010 - 12:15 PM

What you quench in and how hot you temper at depends on: the material, the intended use, the crossectional shape, and finally personal preferences. So when asking questions about it you should include as many of these as possible in the question. I would not heat treat a center punch the same way I would a knife blade, or sucker rod the same way I would leafspring.

eg: I want to make a knifeblade (intended use, crossectional shape) from leaf spring (material); the personal preference can be worked out when you try a method and then decide how to alter it to suit yourself.
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#5 FieryFurnace

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Posted 20 January 2010 - 07:25 PM

I quench in used motor oil!
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#6 dablacksmith

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Posted 22 January 2010 - 09:02 AM

i prefer vegtable oil or a mixture of beeswax and crisco for portable (it dosnt spill for transport).ether one smells better than motor oil..

#7 ThomasPowers

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Posted 22 January 2010 - 11:02 AM

If you quench in used motor oil and then want to draw temper in the kitchen oven you will be in the doghouse!
If you quench in vegetable oil and then want to draw temper in the kitchen oven you can generally get away with it!

(married 25 years so far...)
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#8 Spears

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Posted 22 January 2010 - 12:19 PM

I just bought a small toaster oven to avoid the engine oil in wife's oven circumstance. Lowes and Walmart have small ovens less than $100 that will go to 450 degrees and will probably work ok for tempering small parts. I quench in used crankcase oil also. Spears.

#9 reefera4m

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Posted 26 January 2010 - 12:29 AM

I hope you're on the right track because that's basically what I do. I anneal first (5160 leaf spring is too hard to even cut without annealing), forge, rough grind, normalize, drawfile, and sand (to 200 grit), normalize, sand to 400, normalize twice more, then heat to critial and quench in vegetable oil (heated to 140 degrees) then immediately temper for 1 hour at 400 degrees, let cool and re-temper at 400 degrees for another hour.

Normalizing, i.e., heatng to critical and holding for a few minute, then letting air cool, helps refine the grain (make the grain smaller) in the steel. The finer the grain the better potential for good results with hardening.

I've also heard/read in several forums and other articles, as well as from several bladesmiths that 400 degree is the best temperature for tempering leaf spring steel (5160).

In addition to knife blades, I've made a couple of tools. Here is a photo of a couple of woodworking chisels I made from leaf springs. I used one of the chisels to shape the handles (hickory). After an hour or so the chisel showed no signs of wear and was still as sharp as when I started - and that hickory is HARD.

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#10 ThomasPowers

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Posted 26 January 2010 - 11:31 AM

Well that should perhaps be "that 400 degree is the best temperature for tempering leaf spring steel (5160) FOR THAT PARTICULAR USE" as the *best* tempering temp depends on alloy- stated, quench-stated, end use-implied and personal preference, (for lathe and struck chisels I would do a differential temper leaving the shafts tough and the edges hard.)
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#11 FieryFurnace

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Posted 26 January 2010 - 06:02 PM

Those were some nice looking tools!
I would have said 400 degrees was too high but I can also cut leaf spring with a band saw! LOL Maybe I have some softer spring material! I was told no higher than 350 myself and that was for file material!

When I do the motor oil quench I take the excess oil off with a rag and then a wire wheel. I was told not to use vegitable oil! (Then again I was told not to mess with carbon steel much too! LOL) I like the idea of mixing in crisco (that would be about the only thing that junk could be good for.) I don't cart my oil around but it would be nice to be able to! I'll have to try that! Thanks for the advice!

Once again this thread is simply to encourage younger/newer blacksmiths not to be afraid of working carbon steel and playing with tempering. I was afraid, and it cost me for four years in lack of proper tools! I simply don't want the next smith to be afraid to work carbon steel. In my opinion, by encouraging a newer smith to work the steel and create hardened tools, you help the smith gain confidence. If I go out to the forge with confidence that I can produce something nice; I enjoy my time more, and usually can turn out something nice! If I go out with more of an attitude of dispair or the standard "I'll never be THAT good," then usually I do a pretty poor job and am iritated the whole time. Helping a newer smith produce a functional (start with functional then go to professional) tool out of the "mystical" carbon steel, will produce a high level of confidence and help sustain interest in the craft.

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#12 Nakedanvil - Grant Sarver

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Posted 26 January 2010 - 06:44 PM

You guys are confusing me. Back and forth from carbon steel and 5160. Carbon steel is carbon steel. 5160 is alloy steel. Some springs are made from carbon steel some from alloy steel. Most leaf springs are alloy steel, many are 5160.

I agree, "best" for what? 350 might be great for a knife depending on it's use. I draw most low-alloy hot work tools at 700. Even higher for a spring. bout 900 for rigging gear, shackles and such. Hardness is not everything either, carbide forming like you get with carbon steel over about .80 C adds to wear resistance to an incredible degree.

But, in the end, 1600, oil quench, 400 draw is a good starting point for most "mystery metals". And, yes, springs are mystery metal no matter how many people "know" it's 5160.
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