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Thread: Preventing Warpage: Bevels b4 or after HT? Normalize before hardening?

  1. #1
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    Preventing Warpage: Bevels b4 or after HT? Normalize before hardening?


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    Trying to get going making stock removal knives out of 1084.

    I know some makers that send their SS blades off for HT in big batches and they wait to grind the bevels till they get them back so they get less warped ones.

    Starting out, I will be making only single edge knives whose bevels I can grind on a jig i'm making. This will require me to keep the spine side of the blank parralel w/ the edge side. Then, after the bevels are ground, I can grind away on the spine side of the blade to taper it to a point. It would be hard to do that w/ a blade that is already hardened.

    Is it going to be more of a PIA to do the bevel grinding and final patternform grinding of the blade after the heat treat (non annealed) or more of a PIA trying to straighten a fully ground but warped blade?
    Last edited by Vulcanite; 08-05-2012 at 03:05 AM.

  2. #2
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    Unless you are making really thin blades you will grind the bevels first. As far as warp, there are many threads in the past if you search on straightening blades. You can straighten from the quench for a brief amount of time.

    http://www.bladeforums.com/forums/sh...out+the+quench

    After that, you can use the method Rick Marchand posted about recently and straighten during the tempering cycle.

    http://www.bladeforums.com/forums/sh...out+the+quench

    Take the time to layout and drill your pin holes in the tang before heat treat as well.

    Have you tried to find these answers by using the search function?

  3. #3
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    blades will be stabbing type knives from 3/16" stock w/ 3/4-1" bevel grind heights.

  4. #4
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    I read those threads you linked. Thx. I learned that w/ an "interrupted qeunch", which is apparantly when you take the blade out of the oil while it is somewhere around 900 degrees, you can gently bend and twist it true for a time before it gets hard w/ wood tools. If not, you can clamp the blade to some straight pieces of metal during during temper cycles (after the first cycle).

    Ed Fowler, responding to Rick M's thread, suggested normalizing cycles to remove stresses induced on the metal from forging or grinding in order to prevent warpage or cracking when quenching/tempering. Perhaps I should add this, especially since it will be a lot easier & faster to grind the bevels on the jig completly one side and then the other.

    for 1084 This guy recommends three normalizing cycles between 1450 and ca 800 prior to heating for the quench.
    https://sites.google.com/site/clearb...-basics-part-2

    Weird, kevin Cashen says to heat to 1600 and then let it air cool.
    Last edited by Vulcanite; 08-05-2012 at 03:08 AM.

  5. #5
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    Wiser members, if I'm wrong please correct me. To normalize, heat the blade to non-magnetic, ~1450*, then let it air cool to a black heat (when all the glow is out of the blade, when viewed during daylight in the shade). Do this a couple of times before the final heat to quench. This will remove the stresses caused by any uneven heating during the grinding process.

    I think you are getting a little ahead of yourself with worrying about warping before you have even made the knife. Just take one step at a time. I have only made one knife so far, but during that knife I learned/did one thing at a time, annealing, cutting out and profiling, grinding the bevels, finishing the surface of the knife, then the whole HT process. It took me a couple months to finish the knife, mainly due to time constraints, but I learned a ton in between actual work time.

  6. #6
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    I have experienced slight 'warpage' a couple times, both of which were correctable by heating to tempering temp and then bending back in a parallel jig. I wouldn't want to handle a 900* blade. But generally, I find that if you quench correctly (in oil anyway) and do NOT waggle the blade back and forth (instead, cut or stab the oil) that results are generally acceptable. Warping 3/16" stock?? yeah, I'm not worried for ya. I've done 3/32" and 1/16" chisel-ground blades, both oil-quenched, with no warping. My experience is limited compared to many, but there ya go.

    -Daizee
    Beckerhead #int((2/3)*100)
    My knives, etc.: http://crosstownoutdoors.wordpress.com/
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  7. #7
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    Vulcanite:
    Take a few deep breaths. You will get exhausted if you don't slow down. You didn't put any info in your profile, but you seem to be a very excited youth or young adult - take your time.

    You have posted about six threads in the last few days about all segments of making a knife and the equipment and supplies needed....none of which exist yet. Every question and much more is in the stickies. When directed to them for guidance, you usually reply, "I read a little....". Please read more. That will probably make the need for many of these posts needless. Another good way to get info is to read the many, many past and current threads on the exact same questions. The search engine for bladeforums is:
    http://www.google.com/cse/home?cx=01...%3Aqfobr3dlcra
    This will find most any subject discussed on bladeforums.


    One morning, the young bull asked the old bull what all the cows out in the pasture were there for. When the old guy explained it, the youngster said, "Let's run out there, jump on one of those cows and do that!" The old bull smiled ,and said, "No, lets walk out there, take our time, and do it to all those cows. If it gets dark, we can come back tomorrow."
    Stacy E.Apelt
    It is better to die fighting evil than to live under it.

  8. #8
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    Vulcanite is a man on a mission!! Ha!.... he is respectful and eager..... hang in there bud. Stacy is giving good advice. Tackling ONE subject at a time will be easier in the long run.

    As for normalizing. Ed Fowler is good to tell you to avoid warping in the first place... but it does happen and we should be prepared for it. 1450 normalizing is good as long as the steel you are using is structurally sound. If you are forging or just want to be sure to erase any uneven grain size from the mill you need to start your initial normalization cycle at a higher temp(1600F). Every normalizing cycle should be at decreasing temperature after that.(1500F, 1425F as a suggestion) If you are using an open forge and judging by eye... bright red, red, dull red. The decreasing heats refine the grain. You may even want to throw a quench in at 1500F to refine further. If you want it nice and soft for drilling and grinding, there are a few methods for annealing or spheroidizing....

    Quench on your last 1425-1450F heat and bring it back up to 1200F or so a few times, letting it air cool inbetween. For the eye-baller, bring it up to where the color JUST begins to show in a dark room.

    Proper quenching technique can help the battle against warp, too.
    "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge." - Daniel J. Boorstin



    Rick Marchand
    ABS Apprentice Smith
    www.wildertools.com
    rickmarchand@wildertools.com

  9. #9
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    Thx Rick. I have been working towards this all for a couple years. I have spend a lot of time the last couple years getting married and then having a baby plus I travel a lot and have been doing gun stuff. I have been gradually accumulating tools/materials, making and modifying tools and researching. Besides the quench system and a furnace thermometer I finally have everything now except for a few hand tools for metal & leather work and some handle & leather materials. This week or so i just have a little more time than usual for research and acquisition.

    I appreciate Stacy wanting me to pursue things in a moderate manner so I dont' get burnt out or disappointed. Perhaps I will this small belt knife I am scheming before i make the fighting daggers.

    As to the normalizing and probably hardening too I will get a thermometer for the forge, per info in the PID thread, b/c I couldn't be trusted to eyeball it. Plus I don't want to cook my 2000 degree bricks.

    What temperatures does one let the steel get down to between heating it up in the normalizing cycles?

  10. #10
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    Quote Originally Posted by Vulcanite View Post
    .............

    What temperatures does one let the steel get down to between heating it up in the normalizing cycles?
    It is all covered in the stickies!
    Stacy E.Apelt
    It is better to die fighting evil than to live under it.

  11. #11
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    Vulcanite, Just slow down and listen to Stacy, go read those stickies, they sure helped me when I started (Which was a couple of weeks ago, actually), especially the guide to knife making that Stacy had wrote for us new knife makers.

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