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Post by Matt993f.o.d on May 22, 2008 20:26:11 GMT
Sorry! No pics yet! Will upload them at the weekend. After my disaster with my first attempted knife, I was a bit more careful with the second. I forged the whole blade at a nice cherry red, and was rewarded with a much safer experience. Far less scale, too. The knife is a paper knife, done freehand (not much planning ). Turns out the steel is around 45-50 points of carbon, so it won't be particularly hard edged when done, but should be good enough to fulfill its intended purpose (slicing the cellotape on parcels, and opening letters). I am tempted to put a cannel grind on the edge to help it hold its sharpness. Being of a softer steel, I think a flat or hollow grind would be asking for trouble in the edge holding stakes. I will temper it on the hard side, as well. I havnt done any heat treating yet, so it will be my first go. To harden, I am thinking a water quench will be a good plan for a low carbon steel. Perhaps warm (45 degrees C) water, for safety? I will temper in my oven at 230 degrees C for 2-3 hours. Hopefully this will result in a yellow temper color (harder, and less springy). I found knife forging quite rewarding, and far easier than I initially thought. I was proud of my forging. It was smooth, even, left no hammer marks and no scale indentations. I managed to place hammer blows fairly evenly on each bevel. I also managed to keep the edge and spine of the blade pretty even, and smooth. The blade is only ready for rough grinding at the moment. I have photos of it before the rough grind. Photos will be posted at the weekend sometime, when I get to use a good computer. As I type the blade is annealing in the ashes of the fire. Can't wait to get the old files out on it.
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Post by Deleted on May 22, 2008 22:01:41 GMT
congrats on the first knife!!!!!
cant wait to see some pics
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Post by Deleted on May 23, 2008 2:39:33 GMT
well im still a lil behind on the forging but for heat treating where i have a lil experience i would use a brine solution (salt and water) to be safe. i kinda hold my breath every time i do a quench because during the quench if you hear the dreaded *crack* that u feel deep in your soul u know that all of your work was for nothing. but thats just me im still very new to this.
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Post by Matt993f.o.d on May 23, 2008 22:00:26 GMT
I won't risk brine I don't think, as it is faster acting than water, and if anything will make it more likely to crack. If I can't get it to harden with water, then I will move on to brine. I cannot be completely sure as to what the steel is, as I am using scrap. It should by all rights be 45-50 points in carbon. Also, I will test for cracks after tempering, by striking the spine of the blade lightly against the anvil horn. A dull noise means a cracked blade.
Got the rough grind finished. I chose to flat grind it in the end. The bevels are evened up (they are perfectly straight and true) choil cut made, handle cleaned up and blade polished to a thousand grit finish. That should make polishing after the HT much easier. I ground the edge to around 15-20 thousandths of an inch in thickness, so hopefully they won't warp in the heat treat.
After the heat treat, I will polish the blade to a mirror shine by repeating the 400 and 1000 grit polishing stages, then polishing to 2000 grit. After this I will buff it on my buffing maching with stainless buffing compound. Then I will sharpen using my nice new double sided water stone, which I will soak overnight the night before. Finally I will strop the edge on a scrap of leather imbued with jewellers rouge. The handle will then be roughed up with 180 grit wet and dry, primed in autobody etch primer, then keyed up and painted black. Should look ok when done.
Pics to come when it is finished.
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Post by Deleted on May 24, 2008 0:16:07 GMT
wow thats weird the site i was at said that it was safer than water because the salt keeps the bubbles from leaving an uneven hardening which leads to cracking.
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Post by Brendan Olszowy on May 24, 2008 3:01:34 GMT
Why not use vegetable oil? I just use Canola coz it's cheap, though peanut oil is recommended.
Also I haven't ever had anything crack while heat treating, so be brave. I pre heat my oil. Also avoid swirling around in the cooland when quenching. Just hold it still.
Are you going to temper in coals, or in the home oven?
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Post by Matt993f.o.d on May 24, 2008 21:47:56 GMT
Here are some pics. Bear in mind that the blade is only at the rough grind stage, and still needs tidying, the heat treat doing, final grind, sharpening, polishing and the handle painting. Blade finish is 1000 grit. Here is the whole blade; The blade itself; A close up of the handle twist; And another pic of the blade; Hey Bren, I would use oil, but the blade hasn't got much in the way of a carbon content, so SHOULD be more responsive to a water quench. I am going to experiment with some scraps first, hardening in oil, water and brine to see which gives the best result. Once I determine the best hardening medium, I will test harden the fragment of blade that was the result of my failed first attempt. If that doesnt warp, I will harden my final blade. Tempering will be done in my oven, at 230 degreed centigrade, to aim for a straw yellow temper color.
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Post by 293master293 on May 25, 2008 0:44:26 GMT
Sweet. I love what you did with the handle.
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Post by Deleted on May 25, 2008 1:46:56 GMT
Looks good.
You are overthinking the whole heat treating bit, steel like that, it's the very simplest of simple steels. heat it up, quench in water, temper in oven at 400 for an hour, no need for anything more.
That is, as long as you are confident it has no more than 40 carbon, with junkyard steels however you can NEVER be sure.
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Post by Matt993f.o.d on May 25, 2008 21:52:56 GMT
See, I can't be sure. I consulted a learned chart, and the usual material for jack handle steel in the UK is equivalent to 40-50 point plain carbon steel. I spark tested this material, though, and it gives slightly more complex sparks than a leaf spring that I am pretty sure is 60 point carbon steel.
Thats why I am thinking that I will experiment with different quenching mediums to find the best, then do the final product. I have engine oil, sunflower oil, water, brine and low alcohol solution (a Hrisoulas suggestion).
I did an experiment with running the colours, as my plan for tempering is to stress relieve in the oven at 230 (about 400-450 degrees F) for two hours, then to draw back the spine of the blade using the torch method (holding the edge in the water bath, to keep it cool). I must say how crap I found torch tempering! It is really hard to keep it even and not get a totally spotty temper! Barely worth it when ovens are so much more even and efficient.
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Post by Deleted on May 26, 2008 14:09:13 GMT
It's bad to try to base the sparks of one mystery steel-jackshaft- off of another mystery steel-leaf spring-, the spark test only works when using known samples, when neither steel is definate then all you get is useless rough approximations. Rule of thumb with mystery steel, try oil first, THEN water or brine at your discretion(water will sometimes cause a problem whereas brine would not, because brine cools the steel much more evenly then water, even if it might do it faster the fact that it is more even causes less stress, evenness in heating and cooling is the key).
IMHO, torch tempering is ridiculous, if you temper the blade in the oven properly there shouldn't be a problem. it get's easier the more you do it (practice practice practice). They say it helps with flex, but flex is all geometry anyway.
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Post by Matt993f.o.d on May 26, 2008 18:06:20 GMT
I agree. I find it odd that people even bother with torch tempering and its variants these days. Its in all of the books! If you have an oven, why bother with it?!
Got the blade completely finished. More pics to come.
For the HT, I found oil insufficient to harden the blade. Water, however, had the blade skating a file nicely. I tempered in the oven, at a temperature approximately aiming for a straw yellow. What I got was a completely even purple. Guess the temperature scale on my oven is a little off! I think I should have checked it more often. Although purple will be a little on the soft side for such a knife, I figure its no big deal, because the knife is only going to be cutting paper and parcel tape.
After tempering, the knife took on a barely perceptible (but annoying) corkscrew warp. The majority of this was removed by cushioning, then squeezing in a vice. I think this slight warp was a by product of poor twisting technique when putting in the handle twist.
The blade is amazingly springy! A by product of the softer temper, perhaps.
The blade was polished with 400 and 1000 grit, then finely buffed to a rather fetching mirror shine.
Got the blade sharpened on a rough waterstone, then on a fine oilstone. Not too chuffed with my sharpening technique, though. I think I shall practice.
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Post by Deleted on May 27, 2008 3:18:05 GMT
Coool good to hear it went great. FLEX, PLEASE, IS NOT A PRODUCT OF THE TEMPER IT IS OF THE GEOMETRY. Purple is not so bad for a knife. Was it the handle or blade that took on a corkscrew? Did you check it before hand, I have done that, got all pissed then remembered I forgot to check if that was there before:D.
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Post by Matt993f.o.d on May 27, 2008 17:47:28 GMT
Thats quite controversial. Most of my reading material would argue that temper is related to flexability. What do you base it on?
I am inclined to believe what you say, as I am halfway through making a spring fuller with an non heat treated mild steel bar for the spring, and it is perfectly springy in as-bent condition.
It was the actual blade that went corkscrewed. I had it completely straight before hardening, and it was still straight after. I had a real thorough check. It corksrewed whilst tempering, in the oven.
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Post by Brendan Olszowy on May 27, 2008 18:16:29 GMT
So it corkscrewed in oven tempering? Maybe it's not all that much better than the torch. Was the whole blade room thoroughly room temp when it went in? As for flex I think it's probably fair to say it's a factor of both Geometry and Temper. An untempered blade will snap before it flexes much, and a cube will not flex much either.
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Post by Matt993f.o.d on May 27, 2008 19:32:29 GMT
Sam said in another thread (can't remember which one) that a hardened blade will flex just as much as a tempered one of the same geometry, but will snap once its limit has been reached, rather than taking a set.
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Post by Matt993f.o.d on May 27, 2008 19:36:25 GMT
Here are some pics of the final product. Here is the knife. Here is the blade. Notice that my fingers are reflected in the mirror polish. Here is the now painted handle. Here is another picture that shows off the polish; (the smeary bits are the oil that is coating the blade at the moment) And another; Hope you like it. I have started another one already. Other projects include a twisting wrench and a spring fuller.
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