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Tempering question

Discussion in 'Heat Treating' started by Jackson, Mar 3, 2015.

  1. Jackson

    Jackson New Member

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    Today, just for some practice knife making I annealed a old Nicholson file. Yes I know what most of you are thinking right now. Anyways I cut it to shape,filed,sanded to 400 grit and hardened it to non magnetic quenched it in canola oil. I let it cool and put it in my little shop oven at 400* I got busy with something for about 15 mins and when I checked the thermometer it was 450* I lowered the temperature to 400* watched it for awhile and left it for two hours. I was a bit worried about the temperature spike in the beginning so I spent a bit of time on google and some were saying Nicholson file steel is generally 1095 and 400* would result in a "chippy blade" Its intended purpose is a kitchen/paring knife. What are your thoughts ??? Some are talking about two or even three tempering. Should I retemper at a lower or higher temp. Its not going to be a pry bar and I would like it to hold a very sharp edge. Not asking much for my first knife I know. ;}
     
  2. Mythtaken

    Mythtaken Staff Member CKM Staff

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    I wouldn't worry about it myself. I don't think a few minutes of higher temperature will make that big of a difference. If you'd left it for the whole two hours, I'd be more inclined to start the heat treat over.

    I would do a second temper, however.
     
  3. dancom

    dancom Dust Maker Best Shop Tool

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    Jackson,

    It's good that you are using a thermometer. Most of these little toaster ovens can be off by 50°F and you'd be none the wiser. Temperatures can vary widely within different areas of the oven itself, so you're very likely going to be okay.
    I sometimes use my little oven to straighten knives that are warped. A single blade can get many hours/cycles in the oven. I never go higher than the original intended temperature. Lower is okay.

    There is an excellent page written by Tracy Mickley which can give you some pointers.
    http://usaknifemaker.com/metals-c-9...-c-93-35/heat-treat-information-data-faq.html

    Dan
     
  4. Jackson

    Jackson New Member

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    Thanks Guy's, I really appericate you sharing your knowledge and advice. Pictures will follow.
     
  5. Rob W

    Rob W Active Member

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    .......nothing wrong with Nicholson knives Jackson , sell lots of them , and always getting requests' for them , great novelty gifts and can in fact make really good knives , true maybe not the best steel but remember the original intent of the file was to cut !! Some will say $hitty steel but I think they mean there is better steel to choose from which is the case for any knife, then it just becomes personal preference.....your single temper at 450 is completely fine for the short time , even the long term had you not caught it in time....I temper Nicholson as 1095 at 425-450 , yours being a kitchen paring knife should be just fine , good luck with the finish and post up a pic when done.....grab any files you can , good practice steel and remember people like them !! my ferrier drops them off couple times a year to fulfill the knife rasp demand, and the price is right !!
     
  6. Rob W

    Rob W Active Member

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    Dan if you normalize you may reduce your warp blade count....
     
  7. dancom

    dancom Dust Maker Best Shop Tool

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    Thanks Rob. I had the same question as Jackson about multiple temperings when I did an AEB-L chef's knife and needed to straighten it. I recall what our discussion on knifenetwork, something like "as long as you are less than the original tempering temp". It was okay and the blade was good and hard. I haven't had too many go wonky, but they haven't been "filleting knife thin" either.

    I use air hardened steels. For normalizing, do you pull the pouch at 1000°C or so and let it cool in air, then re-heat/repeat?

    Dan
     
  8. Jackson

    Jackson New Member

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    Both of the files, 8" and 12" warped when I annealed them. The small one after I hardened it, was perfect. After tempering it had what I would call a straw colour. I went to the Chilliwack gun show today and talked to a few knife makers. Really enjoyed that. Nice Guy's. One in particular, I was amazed at how cheap he was selling them for. Beautyfull knife with leather sheath for $140 I've come to understand why they are priced at what they are generally. I would liked to have talked with them more, but the Wife wanted to go to a open house in town :(
     
  9. RHGraham

    RHGraham New Member

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    Nicholson uses quite a good clean 1095 for their files and it's a good choice for knifemaking.

    450 will leave them around 60-61rc and 500 will land them right around 58rc.
    Personally I believe the simple steels perform better all around at the lower hardnesses, 57-59rc, than they do in the 60+ range, which is better suited for the higher alloy steels like 30v and what have you.
     
  10. Jackson

    Jackson New Member

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    Thanks for all the info, I have three pieces of 1084 I got from Canadian knife makers supplies but with all the old files I have laying around I'll likely be making a few more file knives. I think the next one will be a bush craft type hunting knife. Then I'll start making a leather sheath. Great new hobby this knife making ;) PS. What would be the approximate hardness of 1095 tempered at 400* F
     
  11. dancom

    dancom Dust Maker Best Shop Tool

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    If the gods were smiling, you'd end up with a post-temper hardness of around 62C. IMHO that's "chippy". I'd be shooting for a little lower, depending on the end use. 58-59 is pretty good balance for hardness general use and sharpening. Try a higher tempering temp, say 500°F. That will soften it slightly.

    Dan
     
  12. robin sorenson

    robin sorenson New Member

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    Hello all I just joined the forum and have been enjoying reading everything everyone has to offer! Amazing resource!

    I have been using repurposed material for guards and handles making it really cheap to get into the craft... what I didn’t cheap out on was steel I purchased some 1095 and some O1 tool steel. I have only made 4 knives so far using the same method. I’m not forging anything it’s all stock removal. This is what I have been doing please let me know what you think.

    Thermos cycle once slowly bringing up to temp and letting cool to the touch.

    Heating to non-magnetic/one shade past cherryish... quenching in preheated canola 130F ish. Leaving in the oil until I don’t see any movement in the oil. Remove from oil and let cool to touch.

    I’ve been using a bbq at 425 for an hour. For tempering.

    So far everything has been good one of the knives I’ve been using in the kitchen for the last month. Just a little touch up with a steel and it’s good to go! I’m not building a competition chopper or anything. I’m primarily focusing on utility,skinning,fillet, and kitchen knives. Any input for you all would be greatly appreciated.
     
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  13. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    Welcome Robin. Sounds like you're well on your way. Good to have you in the group
     
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  14. cuatroXcuatro

    cuatroXcuatro Active Member

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    I keep a large piece of steel in my toaster oven, I preheat the oven for 1.5 hours before use and have an external thermometer that has an attached cable probe and a settable high temp alarm. Got it at Home Hardware for $20, really handy, has a magnetic case so I can stick it where I can see it. The steel in the oven helps even out the temp fluctuations and the alarm lets me know if the temp has risen past whatever threshold I have set it to. Only has a high temp alarm and not a low one but still pretty handy.
     

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