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Thread: Preferred RC Hardness

  1. #11
    Thanks!


    "If there’s something worth doing, it’s worth overdoing.” - An US saying.

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  2. #12
    Quote Originally Posted by Bill Burke View Post
    Marko 52100 will hold up fine at 63 If you have refined the grain sufficently. I do this with multiple quenches after forging then normalize three times then sperodize aneal and grind. I then tyriple quench and triple temper then finish grind and polish. I still use a torch to harden and an oven to temper. However I would be willing to change my ways if someone can show me a way that works better.
    so why not use the kiln to heat for quench bill? least for the kitchen there is little to no need for a soft back or the ability to bend 180degrees many times (maybe on a single bevel to straighten after honing)

    is it that you like the edge to have all the grain refinement ? why not make the whole blade just as refined? is there a benefit to having a spine thats not as refined as the edge ?


    if you still wanted just a hard edge you could always just edge quench

    i love the kiln for repeatability while im not questioning your heat color eye witha torch (ok maybe a little ) why not have a +/- of under 2 % and know for sure what your temp was (yes i know kilns can go bad too)

  3. #13
    Evenheat kiln will have some variation in temperature (one zone and a temp probe at the top). You can figure what the likely temp of your piece is by some experimenting heat treating and measuring hardness, but you still might be off by 10-25 degrees at low temps and more at high.

    Sugar Creek kiln is better this way, as a probe is on the side, just above the floor level, but it has two rows of coil instead of 4 of Evenheat (it will heat up more slowly), and at $200 less, it might not be a better deal over Evenheat.

    In that sense, you don't get precise temperature measurement, unless you add additional sensors into the kiln or able to measure temp of heated piece with an infrared thermometer (industrial grade - very expensive, all others - inaccurate). To know at what temp you heat treat and temper, you have to do a bit of experimenting, testing for hardness and recording your findings. There will be some guess involved at all times.

    Which is to say that it will be not that different in terms of accuracy than torch heat treating. Heat treating with torch (by eye) could be pretty accurate, as long as your eyes are not failing you and you test your work for hardness and cutting ability regularly, as I believe Bill does.

    M


    "If there’s something worth doing, it’s worth overdoing.” - An US saying.

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  4. #14
    also good to have a baffle for at least the sides of the blade to keep the heat even and not being directly "blasted" buy the coils when they cycle

    the added mass also helps keep the temps for swinging wildly

    and for the guys that temper in there home oven or toaster oven a brick or 2 will help leaps and bounds (keep the blade between the heated bricks )

  5. #15


    Bill Burke's Avatar
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    Quote Originally Posted by l r harner View Post
    so why not use the kiln to heat for quench bill? least for the kitchen there is little to no need for a soft back or the ability to bend 180degrees many times (maybe on a single bevel to straighten after honing)

    is it that you like the edge to have all the grain refinement ? why not make the whole blade just as refined? is there a benefit to having a spine thats not as refined as the edge ?
    if you still wanted just a hard edge you could always just edge quench

    i love the kiln for repeatability while im not questioning your heat color eye witha torch (ok maybe a little ) why not have a +/- of under 2 % and know for sure what your temp was (yes i know kilns can go bad too)
    One of the things that helps with fine grain is how quickly you can heat the steel to austenitizing temps. An oven is not very fast. Salt or lead is pretty fast and I have been doing some playing with salt. a torch can be very slow or very fast or in between what ever I want. I can also dictate the size and shape of the hardend portion of the blade, From just the edge to the entire blade, much better than heating the whole blade and doing an edge quench. Lastly I have done it this way for so long and I get such good results that I am very reluctant to change things now. Not that I won't change but there will have to be some pretty strong evidence and definitive proof before I do.

  6. #16
    What do you use for a baffle, Butch? I got two extra bricks with Sugar Creek, wonder if this is what they are for.

    M


    "If there’s something worth doing, it’s worth overdoing.” - An US saying.

    If my KKF Inbox is full (or not), please contact me via Email: anvlts@gmail.com

  7. #17

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    Roman Landes swears that W2 can and should be left harder than "normal" even for field knives. I think he leaves his at around 62RC.

  8. #18
    Delbert Ealy's Avatar
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    Quote Originally Posted by Marko Tsourkan View Post
    Evenheat kiln will have some variation in temperature (one zone and a temp probe at the top). You can figure what the likely temp of your piece is by some experimenting heat treating and measuring hardness, but you still might be off by 10-25 degrees at low temps and more at high.

    Sugar Creek kiln is better this way, as a probe is on the side, just above the floor level, but it has two rows of coil instead of 4 of Evenheat (it will heat up more slowly), and at $200 less, it might not be a better deal over Evenheat.

    In that sense, you don't get precise temperature measurement, unless you add additional sensors into the kiln or able to measure temp of heated piece with an infrared thermometer (industrial grade - very expensive, all others - inaccurate). To know at what temp you heat treat and temper, you have to do a bit of experimenting, testing for hardness and recording your findings. There will be some guess involved at all times.

    Which is to say that it will be not that different in terms of accuracy than torch heat treating. Heat treating with torch (by eye) could be pretty accurate, as long as your eyes are not failing you and you test your work for hardness and cutting ability regularly, as I believe Bill does.

    M

    My kiln was made by evenheat, but it is not a traditional knifemakers kiln. Mine is vertical 36 inches high and has 16 rows of coils. My controller(Omega) and thermocouple was not included and I put that system together myself. They are located in the middle of the kiln right where the blades go. I have tested my system with yet another thermometer and my system has an accuracy of 2 degrees even in the 1500f range.
    I believe in constant testing and even test-to-destruction and I do that to insure quality control.

    I strongly believe that making a blanket statement about the accuracy of all kilns over other methods of heating is inaccurate and misleading.

    Laminated metals specialist, Kitchen knife and gadget maker
    www.ealyknives.com
    www.mokume-jewelry.net
    "Build a man a fire and he will be warm for a day, set a man on fire and he will be warm for the rest of his life"

  9. #19
    Quote Originally Posted by Delbert Ealy View Post
    ...

    I strongly believe that making a blanket statement about the accuracy of all kilns over other methods of heating is inaccurate and misleading.
    I was not referring to vertical kilns, or salt pod kilns, but horizontal kilns in general and from Evenheat and Sugar Creek in particular (have both), basically one temperature zone kilns. I would bet that one would get different readings if one installs two more temperature probes in this type of kilns. For the users, there will always some guess work involved when heat treating at higher temperatures (Evenheat kiln temp difference near the probe and the bottom where a knife is located is over 25 Degrees), so to know where you are, one has to do a variety of tests at different temperatures and then test for hardness (not with files, but with an actual hardness tester). Then temper, measure hardness, destruction test and grain analysis. After some trial and error, one can come establish the optimal heat treating temperatures.

    What I do find misleading is when people state particular hardness on a finished knife without using a hardness tester. I accept that experience will help one to establish a range, but not an actual number.

    M


    "If there’s something worth doing, it’s worth overdoing.” - An US saying.

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  10. #20

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    In my previous life my boss showed me his Puma pocket knife one day and you could see the Rockwell indentation on the knife and they scribed the number right next to it. Very impressive to me. I've never seen that on any other knife. He told me it was an old knife and even Puma had stopped doing it. Shame, I thought it was pretty classy.

    I still have problems with Rockwell reporting. I remember my standards were +/- 0.5 at best, example 50 HRc +/- 0.5 would be scribed on the side and the dial had 5 unit increments if I remember correctly, 90, 95, 100... etc. The machine didn't have the resolution to differentiate between 60 and 62 nor the tolerance to do so either. This was on my old Wilson unit. Maybe those fancy digital ones are a whole 'nother ball of wax.

    -AJ

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