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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making. |
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#1
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Tempering on a Evenheat or Paragon kiln
I am finally biting the bullet and getting an HT oven.
I was all ready to buy a Paragon KM36d, then i saw a recent thread about tempering issues with the Paragons 36" models. I wanted to clarify this important point before plunking down that kind of cash I contacted paragon and was told if i wanted to temper in the oven i might have to raise the temp extremely slowly around 100 degrees an hour. I contacted Evenheat and the sales rep, who I didn't think was very knowledgeable from the start said the Evenheats had no problems getting 400 degrees and maintaining it within a small window. She stated that the small window was +- 50 degrees. this seems like a very large window to accurately temper. My question to anyone out there: Are either of these ovens good for tempering? If not what do you use to temper with. Hopefully someone can give me some insight, i know the lead time on these ovens is 3-6 weeks and I want to get it before winter hits. |
#2
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I bought a secondary used kiln specifically for tempering , has a dial not digital , an older knife making kiln that works excellent and was cheap....my digital pyrometer indicates I'm within a couple degrees for any length of tempering time required.....the toaster ovens are not consistent and the wife didn't like the oven being used......i looked around for a while , lots of cheap kilns available just snoop around a bit
__________________ R.Watson B.C. Canada |
#3
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I was hoping for $1600 I would be able to do everything in it. I don't have alot of floor space available, especially for two kilns large enough to handle a 36" blade
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#4
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If I start my Evenheat from cold to 425?, it will not over shoot more than a couple degrees. Same if I reset to 425?, with temp below 250? after it cools from 1475?. No matter which you use, you have to wait for it to cool down. That may be problem with some steels, unless you can some how snap temper until the cool down. I use 01 which isn't very prone to crack if I wait, but 10xx steels and some others may. 1095 would be high risk. Even a snap temper at 300? should allow you wait, but I don't have a suggestion as to how. Also. You may not be able to do a 36" blade without getting the point too close to the coils, and having it over heat. I would think you would be limited to maybe a 30/32" length, counting the tang, giving you closer to an actual, maybe, 24/26" blade, unless you intend adding some tang after the HT.
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#5
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Maybe I will have to go with a evenheat after all. I am still hopeful to hear from someone with a paragon as to their tempering performance.
As for the tip overheating I figured I could just turn the bade around since there are no coils in the door. |
#6
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Just "possibilities" I see. A blade that large, and or that long, may be difficult to change ends on, without help. You would also be gripping the blade where it is thinner, thus giving the heavier end an opportunity to cause droop. Your tongs may act as a heat sink where you would grip, and may leave marks in the red hot blade. Swapping ends could be a dangerous maneuver, even with help. The time spent swapping ends, may allow the blade to cool more than ideal before quenching. If you over heat to allow for the time taken in swapping ends, you may get grain growth. If I were to HT a sword, I think I would use either a long coal forge with a heating chamber and pyrometer set up, or an upright propane forge with a back door cut out in order to move the blade fore and aft. I have one of those, but it was damaged in a flood. I never used it for HT, but could see it would work pretty well. The design was a fairly simple one, by one of the well known sword makers. Cannot remember his name, but look up propane sword forges. I don't know what you could do about controlled tempering, other than heat color. You might pull it off with a forge chamber arrangement, and pyrometer.
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#7
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Quote:
Gary __________________ Gary ABS,CKCA, ABKA,KGA |
#8
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Gary, do you have a paragon or an evenheat?
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#9
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Tempering temps in a Paragon will fluctuate as it will in an Evenheat......the issue with either is if your ramping up to heat treat temps between 1400-1900 be it mild or stainless steel you'll be waiting for it to cool down to tempering temps......and forced cooling i.e. a fan is not recemennded , this is why I went with a secondary kiln for tempering.....from my Paragon to quench and into my secondary preheated kiln to whatever temp required for 2 or 3 cycle tempering.....best $150 I invested in my shop......and yes I would buy a Paragon again if it was my first oven , good luck , join the club , be happy , all good
__________________ R.Watson B.C. Canada |
#10
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I recently purchased an older paragon oven. The inside dimensions are roughly 13 inches deep by 13 inches wide by 9 inches high. The temp "controls" are a simple knob with low to high positions, but there is no feedback mechanism to regulate at a given temp. The setting mainly influences the rate at which the temperature increases at. I suppose using a PID controller would be a simple matter to gain in controlling the temp around a given temp setting.
I have yet to actually attempt to HT a piece of steel in it, but my intention is to just watch it closely and crack open the door periodically to control temp as needed. In my "test run" I was able to do this with relative ease, but I don't know if doing this would have any negative impact on my blades. I really don't see why it should. Also, I am unsure as to if it would be better to insert the blade when the oven is cold and let the blade warm up as the oven temp increases or would it be better to allow the oven to reach full temp before inserting the blade into the oven...or does it matter. Prior to acquiring this oven, I used a toaster oven so I think I will be more consistant and do a better job using this "new" oven...but if anyone would care to offer suggestions...I'm all ears. Thanks. |
#11
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#12
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I have only had an Evenheat but have never been entirely satisfied with it. Were I to do it all over again, I would buy the Paragon. They are built much more durably.
I think that you will find that most (myself included) use a secondary oven for tempering for the various reasons previously stated. You stated earlier that you need a 36" oven. That is very large and most of us can't give you advice on one since few use one anywhere close to that size. I would suggest doing the needed research before investing and decide the best size that will be required for your work. I would go with the smallest oven that will get the job done as there are advantages to it. All my best. Gary __________________ Gary ABS,CKCA, ABKA,KGA |
#13
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There is a video that shows a toaster oven that has a thick piece of steel plate in it and the knives are placed on top of the plate to temper. The idea was it will regulate the temp. and keep it from jumping up and down so much as the oven cycles. What do you think of that? Would that really help. Ed
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#14
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#15
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I started making knives because of my fascination with medieval swords, and I figured baby steps. One of my limitations was the fact I couldn't HT anything over 12' long. Buying a KM36d would big the big push to move me towards my original goal. Hence my need to be able to temper in it as well..
Other than cost to run a larger kiln what would the benefits be to go with a smaller kiln? Many of the people I have talked to say get the largest you can afford. |
Tags |
1095, art, back, blade, bullet, cold, degrees, design, digital, forge, handle, heat, heat treat, help., hot, knife, knife making, making, problem, simple, small, stainless steel, steel, tang, temper |
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