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I'm interested in making my own blades for woodworking hand planes by removing stock from O1 bar. The largest blade I intend to make is 2 5/8” x 1/8” x 8”, but 3" from the edge is all that needs to be hardened. One of the reasons I’m interested in doing this is to save money. So, I’m trying to figure out the best way to economically heat up to the curie temperature before quenching in oil and annealing in my toaster oven.
I’ve ruled out heat treat ovens. Even the homemade jobs look a little pricey.
I’ve seen a few coffee/paint/bean can forges that I think usually use mapp torches. I like the way they look. Easy and clean. I would really like to use the propane torch I have, but would it get hot enough? On a couple youtube videos I’ve seen, these forges seem to have a nasty localized hot spot at the flame. That got me thinking I’ve pretty much got everything I need in the garage to make a brake rotor forge. I could probably bang one of those together and buy a bag of charcoal in less time than it takes to track down a fire brick, inswool, and refractory cement. Of course I do have neighbors within throwing distance on all sides…
Do you have any advice?
Am I overlooking a better method?

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Welcome to I Forge Iron. Attempting to differentially hardened O-1? good luck, I would advise against that, start out with a full hardening, then you can differentially temper. This way is easier and with better control of the tools strength than having only a partial martinsite tool, leave that trick for simpler steels, and for after you get a better hang of this stuff..

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With practice you should be able to do that size with a plumbers torch and one or two firebricks. The firebricks should be available at a place that sells wood burning stoves. The soft are better but the hard are better than nothing.

Have all materials ready.

What I would do. After shaping, before final grinding....
Set the iron on the brick. Light the torch. Play the flame over the iron until it glows. Watch for the decalescence (sp?). OR use a magnet. Give it just a bit more heat. Quench in an appropriate medium. Check with file. Temper.

*Note: O1 does best with a soak that you probably can't achieve without an oven. You may get better results with plain carbon (1080 or 1095).

You can go with a stacked brick forge. Or dig a hole in the ground and run an air pipe in (will work for solid fuel).

ron

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A charcoal forge using real chunk charcoal should never even be noticed by the neighbors---what will they complain about your charcoal grill?

I've seen propane torches that can cut 2" thick steel and others that would have problems heating a cup of coffee.
How can we tell if your propane torch will work if we don't know anything about it other than you own it?

A small propane forge would be a great idea as it can be used indoors with proper ventilation and MI starts getting cold real quick. Note PROPER VENTILATION---if you gas yourself all your woodworking equipment will be sold for a pittance to an "artist" who will make sculptures from it using only an arc welder and a sledgehammer!

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I am a detail guy so this kind of jumped out at me..annealing is a lot different than tempering..you can temper in a toaster oven... not anneal.

"So, I’m trying to figure out the best way to economically heat up to the curie temperature before quenching in oil and annealing in my toaster oven"

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steve sells
What I've been reading has mostly been about heat treating knives where they heat the blade without being too concerned about the tang. They probably were using simpler steels than O1.
I wasn't talking about any kind of samurai sword thing, but just heating the only area of the blade that will ever see an edge seemed like it would be easier to accomplish. Would this cause warping, or cracking in O1?

son_of_bluegrass
So, all I need are a couple of fire bricks?
When you say soak do you mean getting an even temp over the whole area or are you talking holding the temp there for a while before quenching? I was hoping a forge would help with evening things out a little bit. I’ve read of folks using both propane and coal forges specifically for heat treating O1. This had me thinking it was the way to go. O1 and A2 are currently well accepted steels used for plane irons, I’m not sure I would want to use something else.

ThomasPowers
I have a hand held plumbers propane torch. It was cheap when I bought it a long time ago and I don't see any markings so I can't tell you the brand. It has always done well at soldering copper pipes together.
I had one of my neighbors call the police one night when I was working in my garage at 11:00 p.m.
You may think they were justified, but I don’t have equipment. I use hand tools that don’t make any noise… half of them are wooden…they might be hard to weld into a sculpture.
I’ll crack a couple of windows for ventilation.

Rich Hale
Your absolutely right I flobbered all over that one.

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One of the problems with differential hardening these 2 steels is that A2 and O1 air harden, (Yes, I said O-1 can air harden in thin sections) if you have un tempered martinsite that is asking for trouble. Uneven heating (which is what we do for differential hardening, is also asking for trouble in higher alloys. just HT the entire unit was all I was attempting to point out.

You are not ready for HT of these in anything but simple forms. I say this not to insult you, but as an observation from your asking these type of questions, that tells me you have no experience with this. It is not that hard to HT it as a whole. Do not scare yourself, remember to not complicate things and you should be fine :), you may not be that far away from me, I would HT it for you, and I am sure that many others closer to you would help walk you through this if you asked.

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Snip

son_of_bluegrass
So, all I need are a couple of fire bricks?
When you say soak do you mean getting an even temp over the whole area or are you talking holding the temp there for a while before quenching? I was hoping a forge would help with evening things out a little bit. I’ve read of folks using both propane and coal forges specifically for heat treating O1. This had me thinking it was the way to go. O1 and A2 are currently well accepted steels used for plane irons, I’m not sure I would want to use something else.

Snip

Rich Hale
Your absolutely right I flobbered all over that one.


You can get by with a couple of fire brick. Or with 6 or 8 build a stacked brick forge. You can heat a larger area easier and evener with a forge (even a simple hole in the ground type).
Soak is holding at temperature for some time to allow all the alloying elements to go where they want to go (way over-simplified ). Don't expect to be able to do that with a torch. It's hard to do with a forge.

So far as your choice of steels. I don't care for either for cutting tools. You'll get better results if you heat treat 1080 or 1095 yourself and treat them specifically for cutting tools.* If you insist on using either O-1 or A-2, I recommend you send 'em out to be heat treated by someone with to tools to do so.

ron

*My opinion based on some of the chisels I've made for myself and the knives I've made for myself comparing to the one or two tools I bought with O-1 and A-2.
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I have heat treated O1 chisels with a torch ( basically same as plane blades )and it will work just fine . Be careful not to over heat the edge I personally would not worry one bit about heating just the edge section , this has and is done all the time.
heat treating can be a simple or as complicated as you want it to be . and the differences between an ok HT and a really top notch one can be very small indeed.
as you are stock removing you do not have to really bother about normalisation as the steel you buy should be in a great condition for hardening.
O1 is a great steel to chose because it is so easy to harden , bring it to critical , just above non magnetic with a torch (soak for best result, but works fine if no soak) and harden in oil . temp to appropriate temperature , I would play with that for your own needs . If you are using the tool yourself you may be able to get away with a harder than normal blade as you are less likely to abuse it!! a kitchen oven or toaster oven will do just fine , just do not assume that the temps you dial in are true , they are often a little out , try and test your blades to ascertain what works best for you
get the job done simply...
If you feel the need to delve further in the future there are books and books and books that can be bought and read ! steel is a wonderful material and there is loads of interesting stuff to learn about it.
All the best Owen

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