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The Newbies Arena Are you new to knife making? Here is all the help you will need. |
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#1
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Hardening with a 1 brick forge
So I made the forge and figuring out my plan for hardening. I am using a burn o matic with 1084 being the trick. Weather around here can go from 40-70 in two days. Questions I have are:
Do you preheat the brick? How long should I leave it in before I check with the magnet? Any other hints? |
#2
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I'm not too much farther south than you are so I know about the weather. Actually it doesn't have much to do with heat treating.
Yes, I preheat the forge to let it build up heat. I usually run the burner pretty wide open then reduce the flame so as to heat the steel more evenly. I start checking the steel when I see it starting to get some good color on it. I try to catch the steel just as it goes non-magnetic and then try to hold it a little brighter than that for 2-3 minutes. I then quench in warm oil allow it to cool until it's comfortable to handle, scrub the oil off with a wire brush with detergent and then into the tempering oven. Doug __________________ If you're not making mistakes then you're not trying hard enough |
#3
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Weather around here has gone from 40 to 70 and back again in half an hour but that doesn't help you much. I'd pre-heat the brick because, if you don't, then you have to heat the brick and the knife at the same time and that will leave the steel in the heat longer while you try to get the temp equalized.
There's no time to this. You can watch the color for a hint that the temp is in the right area but nobody can quote an exact time or an exact color. Time will vary with the size and shape of your forge interior and your torch placement and the mass of your blade. Color will vary with ambient light, and the way you see and describe color. So, you're largely on your own and practice is the key to learning what works for you in your situation. That said, the blade will be red enough to seem somewhat bright (give or take). It is not enough that the blade is non-magnetic - you need to catch it just as it turns non-magnetic. You want to quench the blade when it is approximately 50 degrees beyond non-magnetic. You will not get proper hardening if you simply come back an hour later and find that the blade is now non-magnetic because it will also be severely overheated. This means watch the color and as soon as it seems you might be in the right area start pulling the blade and checking it, heat a little longer and check again until you find non-mag. Then, back in for 15 seconds or so and quench. Other guys may explain it differently and their processes will be as good or better that what I described. That's why I say you'll have to take what we say, pull the parts that seem to work best for you, and practice until you can get consistent results ... |
#4
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Ray, explained it a bit better than I did. Steel changes phase right after it becomes non-magnetic. I think it's around 50-75? hotter than non-magnetic. The iron crystals in the steel have to change phase to dissolve carbon which will be trapped withing the crystals when it is cool rapidly, that is to say quenched.
He's also right about being different for different people. I keep reading that the steel should go non-magnetic right about a dark cherry red. I've yet to see red at my forge. It's all shades of orange until the steel turns yellow, which is way too hot for maintaining good grain size. I don't know if it's my color perception or the ambient lighting in my forge area but I just don't see red so I have to learn the color as it applies to my set up and me. Doug __________________ If you're not making mistakes then you're not trying hard enough |
#5
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That's my concern. I have a bit of color blindness lol. So when I am heating I want to draw it out and in of the forge. Run the blade portion a magnetic once I see the color I need. Quenching blade first correct. Do I need to warm the peanut oil?
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#6
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Also I appreciate everyone putting up with especially Ray you seem to come to my aid quite a bit lol
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#7
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Yes, you need to warm the oil. It sounds counter intuitive but warn oil will cool faster than ambient temperature oil because it is less viscous and wets the steel better.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
#8
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Good to know. Do we recommend edge quenching with a regulator block?
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#9
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Warm the oil to around 110 to 120 deg F (use a candy T-meter to check).
I'd leave the edge quenching until you get comfortable with the quenching process as a whole. Suggest you do a few dry runs and get the steps down before doing the actual quench. Set your forge up high enough so that you can see in it easily and have your quench close enough that you do not have to make awkward moves to quench. Be careful and attentive, those little one bricks will get really hot and the blade will overheat faster than you'd think. As you reach non mag, watch the color/hue of the steel. The thinner sections (tip and edge) will heat faster and they are the critical parts of the blade. Fix on their color and move the blade around the interior until the rest of the blade is the same before quenching. You should use the valve on the torch to regulate the heat, once the blade starts to show color adjust the feed down or you'll most likely burn the thin areas waiting on the rest to match up. __________________ Carl Rechsteiner, Bladesmith Georgia Custom Knifemakers Guild, Charter Member Knifemakers Guild, voting member Registered Master Artist - GA Council for the Arts C Rex Custom Knives Blade Show Table 6-H |
#10
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About the edge quenching, often beginners, and I as no different starting out, see something being done, like edge quenching, and think that that's the way knives are supposed to be made. Especially if we read the ABS performance test rules. Well, it's not true. Edge quenching creates a soft spine which is a design element that can be useful to some blade designs-or not-depending on design philosophy. A soft spine will increase the toughness of a blade at the expense of the strength. Some makers think that being able to bend the knife to 90? without a complete break is the way to go, at least on large blades, and others would rather see a knife that he can hang his weight from without taking a permanent bend or breaking.
There are often design elements, like the soft spine, that are neither good nor bad in and of themselves. They are only things that can be done making a knife. However, they should be done with purpose and with recognition of how they effect the performance of the finished knife. Doug __________________ If you're not making mistakes then you're not trying hard enough |
#11
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Other issues one must consider concerning edge quenching - blade cross-sectional geometry and type of steel. Some steels just do not benefit well from edge quenching as Doug has explained.
__________________ Carl Rechsteiner, Bladesmith Georgia Custom Knifemakers Guild, Charter Member Knifemakers Guild, voting member Registered Master Artist - GA Council for the Arts C Rex Custom Knives Blade Show Table 6-H |
#12
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Thanks Doug. I won't test those waters yet haha.
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#13
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Well today is the day for this. Cross your toes.
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#14
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buy a paragon heat treating oven and stop guessing about hardening and tempering temps. They are not as expensive as ruining weeksof work.
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Tags |
abs, art, back, blade, block, build, design, edge, forge, handle, heat, hot, iron, knife, knives, made, make, making, quenched, steel, toughness |
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