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Ed Caffrey's Workshop Talk to Ed Caffrey ... The Montana Bladesmith! Tips, tricks and more from an ABS Mastersmith. |
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#1
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Anyone have pictures of the perfect grain size?
I made a knife and heat treated it as usual and tempered as usual. Later (after final polish) I was heat treating another knife and went to turn on my tempering oven. I noticed that my thermometer did not go down after the previous temper and it was sitting at 350 degrees.
I use a toaster oven for tempering and a seperate thermometer. Since my thermometer did not work properly, I do not know what temperature the oven was at during the tempering of the blade. I decided to make that knife a test knife and see if I could get a look at grain size. I laid the knife on my railroad anvil with the tip sticking off and smacked it with a hammer. I hit it fairly quick and snapped the end right off. Obviously the oven was not hot enough since the end snapped like that. The grain looks like powder. You can see the grain and it is very small in size. I was wondering if anyone has a picture, or knows where one is, of grains size that is correct (proper temper). I would be interested in seeing the comparison. I do not have the photographic skills (I am sure you all know this) to put up a good picture of my blade grain or I would post it. Might as well learn from this thermometer foul-up. The steel is 1084. |
#2
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Shawn and I destruction tested one of my old blades and eventually snapped the thing, I`ll see if I can rustle up the pieces and get a pic for ya...grain is smooth as silk, can`t actually see grain it just looks grey...hard to describe.
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#3
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Thanks Ron,
Just want to compare this to another and do not want to destroy a good knife to do so. |
#4
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someone correct me if i'm wrong- grain size is from the hardening process, not tempering [also making sure, from anneling that it's small to start with]. i was invited to tim zawodas' shop once, and he showed me about grain size. he ground across a file every inch; stuck it in the forge and intentionally heated the end too hot. one end was a orange hot and the other a dull red. quenched in water; clamped it in a vise and had me start hitting with a small ball pien- holding my finger behind the blade. the part too hot broke like glass, the further down i went, the harder i had to hit. we then looked at the broken edges to see the grain. it was like motar sand to pee gravel- was easy to see. the reason we did this; i had ask what a magnet was use for. he said all the pieces would check at the same high rockwell but the small grain makes a better knife. so, from this i've always assotiated grain size to hardening, not tempering. the tempering relieves the stress caused from hardening anywhere from a hard brittle edge for a skinner, to a softer edge for a camp knife or a softer yet for a sword or spring. forging at high temps, or over heating durning h.t. will both cause a large grain. the reason your knife broke was you didn't draw at a high enough temp. you saw a small grain, so your h.t. was fine, your draw just wasn't high enough. paul
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#5
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bob, please don't interpret my last post as me giving you a lesson in h.t.ing-sometimes a person looks at a problem in a certain way and someone else comes along, says something and then everything makes sense. my post [ and i'm trying to say this right because everyone is not face to face talking- but writing and things don't always come out right] - my last post was as much at helping you look at something you probably already knew in a different light , as to help any new comers [ as if i know what i'm talking about]. paul
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#6
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Paul,
That is really a good exersize, really good. Sounds like that's the type of thing everybody should do once. Including me. Steve |
#7
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Paul,
I know exactly what happened. I just want to compare the grain to another piece, that's all. I could have said that better in my post. I want to match up grain size with the grain size of another heat treated knife BEFORE tempering and after. I am curious how well my normalizing is performing. Just another way to check myself. I am mailing a couple pieces to Ed Caffrey for his opinion. Thanks. Last edited by Bob Warner; 03-04-2004 at 06:28 PM. |
#8
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Here is the pic, sorry it`s not that great I had to try a bunch of times to get a reasonably decent one.
This id from a diferentially heat treated blade, the fine grain is where it`s hard, the coarse is where it`s soft. I heated the entire blade then quenched in Canaola oil at 135F and tempered at 360F for 2 , 1.5 hour sessions. |
#9
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from your picture would it be better to harden the entire blade and then draw the spline back ? there would be a fine grain through out the blade this way, yet stll have a soft spline. one could draw the entire blade to usual remps, then heat the spline to say 500 or until it turns blue- hard edge, spring temper spline with a fine grain through out. it would seem to make a stronger blade. paul
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#10
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I do have the gear to take some pretty microscopic photographs.. some even with a scale in them, if anyone would like me to try to photograph a blade piece for them, I'd be happy to try.
Charles. __________________ If it ain't one thing... It's another. |
#11
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If anyone wants a good gain size gauge to keep handy you need look no further than your work bench. Take a good quality file, like a Nicholson, that has seen better days and snap it, examine the broken file and there is the grain size you want to emulate!
__________________ Guy Thomas/Thomas Knives |
#12
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Guy, good advise. Thanks.
__________________ Happy Hammering, wear safety glasses. Gene Chapman Oak and Iron Publishing www.oakandiron.com/ |
#13
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Thanks Ron. I forgot to say that.
The breaking of the file is a good idea, feel kinda dumb for not thinking of it, but a great idea just the same. |
#14
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this may be a dumb question but I thought that the normalization was supposed to reduce the grain size. So if a blade is normalized right and with enough times should you see and difference in grain size at all from the harden edge and the spine? Just wondering.
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#15
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JimmySeymour,
The way I understand it is that the normalization helps reduce the grain size overall. At the time of heat treat though when the blade is quenched the grain size is reduced even further. That is why you see the difference between the spine and edge. I could be wrong but that is how I think of it. Jerid |
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blade, forge, forging, knife, knives |
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