Question on cpm-3v

Discussion in 'General Knife Discussion' started by rodriguez7, Apr 27, 2015.

  1. rodriguez7

    rodriguez7 Gila wilderness knife works

    Feb 1, 2009
    Im looking into a new knife, just because I want one. Been kind of interested in the Ambush series, which I understand are built by bark river. Curious if anyone knows who heat treats these blades? I never have heard of anyone doing a differential heat treat on 3v. Just wondering if its worth the effort, considering the toughness of 3v. Its kind of between this brand, or a gso 4.7. Anyone have any info. on these? Thanks.
  2. shqxk


    Mar 26, 2012
    3V is air hardening type steel that austenitizing part need to be soak with proper timing. For this reason, differential heat treat is impossible for 3V.
  3. rodriguez7

    rodriguez7 Gila wilderness knife works

    Feb 1, 2009
    Thats what I had heard, I wonder if the information on the ambush knives is just a typo. It says on knives ship free, that its a differential heat treat.
  4. rodriguez7

    rodriguez7 Gila wilderness knife works

    Feb 1, 2009
    Wow, I figured I would at least get a few responses to this. Guess no one knows, or cares?
  5. TennToadsticker


    Jan 5, 2011
    Try Paul Bos on Buck's website. I've heard he does a great job.
  6. Leftytwogunz


    Apr 30, 2013
    For what it's worth I see typos on knife dealer's websites all the time. A lot of times in similar models they copy and paste most of the info and mis-label handle colors, sheath types etc. all the time. I guess your best bet would be to email/call the manufacturer of the knives in question for clarification.

    There is also some info on crucible's data page on CPM-3V.
    Best of luck.
  7. Sonnydaze

    Sonnydaze Gold Member Gold Member

    Jul 6, 2009
    I buy my cpm-3v from survive knives...the gso series.
    Blades are ht'd by Peters. Top of the line HT.
  8. bladeninja


    Mar 26, 2014
    Survive Knives are great but not the best in my opinion for 3v. Try Fehrman knives. They grind then heat treat as opposed to heat treating then grinding. The quality is apparent. This is what the best of the best do. Daniel Winkler does this too by the way.
  9. RX-79G


    Jun 23, 2006
    HT then grind sounds like a rather difficult way to get things done. Why does Survive do that?
  10. tinfoil hat timmy

    tinfoil hat timmy Gold Member Gold Member

    Aug 21, 2014
    This may not apply to 3v, but in my CNC manufacturing classes, I learned that heat treatment can add stresses and distortions to a ground and shaped piece of steel.

    Grinding afterward would seem to make these distortions and stresses in the final piece moot, as it still has to be ground to shape yet anyhow.

    What I personally would do, is do an initial, rough grind, heat treat, then finish grind.

    Again, I know very little about 3v specifically, so my post may just be pig shit.
  11. RX-79G


    Jun 23, 2006
    It is generally thought by knifemakers that nothing about a knife is precise enough to worry about heat treat distortion. Certain alloys are used for tool and die making because they are ultra-low distortion for heat treating, but we don't care.
  12. mete


    Jun 10, 2003
    CPM-3V is a great steel !! It doesn't need any differential HT.
    Grinding -Grinding IS critical for all knives ! Improper grinding after HT will damage the edge and more so the tip. Grinding creates heat which tempers back the edge . Best for finishing the edge is by hand , then by grinding wheel or belt With cooling fluid . By machine without fluid is poor as the heat generated will damage the edge. How can you tell ? If the edge doesn't seem to be right but after two or three sharpenings it's OK then the original sharpening has caused the problem.I've seen that in even the better knives ! Careful metallurgical study shows it very clearly !!
  13. Jeru


    Mar 19, 2011
    I didn't know about all this! Very very interesting thread!
  14. james terrio

    james terrio Sharpest Knife in the Light Socket

    Apr 15, 2010
    Diff-hardening 3V is possible (it's been done - sort of - with D2; look up Dimaond Blades Friction-Forged knives) but it would be crazy expensive and frankly not worth the effort. "Normal", through-hardened 3V exhibits very high toughness and very good abrasion-resistance... which is precisely what it was designed for.

    Yup, all the same principles apply. As mentioned above, it's not nearly as big of a deal in a piece as simple as a knife blade, as it would be in a really complex part.

    But it can still be a major factor on really thin sections, like the edge of a chef's knife. On those, I routinely grind modern tool and stainless steels like 3V and CPM-154 right down to final dimension, with an edge of .010" or less, ready to hone, before HT with no problems... if I do the same with simpler steels like O1 and 1095, they're very likely to end up with an edge that looks like cooked bacon (warped/wavy). That's one of the reasons alloys like chrome and moly are added to high-end steels - to increase stability during hardening and especially during quenching.

    BRKT and most other manu's do the same. It's faster and less costly in the long run, mainly because it cuts down on procedural steps and shipping, and possible warping of thin edges/tips during HT. Simply have steel sent to a laser/punching/waterjet firm, have them ship the blanks to the heat-treater, have the hardened/tempered blades sent to your factory, grind 'em, build handles, done. (The only way to be more efficient than that is to do everything in-house, which is cost-prohibitive for smaller manu's. Larger companies generally follow the same overall process.)

    It's a perfectly legitimate way to make knives, when it's done right. The only problem comes when the hardened blades are ground too aggressively, resulting in over-heating the edge and fouling up the temper... which unfortunately happens fairly often.

    Probably 8 times out of 10 when people freak out over a certain "batch" having "bad heat treat" and not holding an edge like they should, what really happened is they got hold of a few examples that were over-ground. When you rely on either robots or humans who are programmed/paid to crank out X-number of blades per shift, that's gonna happen sometimes.
    Last edited: Apr 28, 2015
  15. Eric@DLT

    [email protected]

    Mar 30, 2015
  16. Neo


    Sep 12, 2002
    When the ambush knives first showed up I also noticed this.
    So I asked on the bark river forum if these knives were different hardened then the normal bark river knives.
    Mike Steward answered they have the same heat treat as all bark rivers on which the tangs are drawn soft.

    So I understand the differential heat treat isn't spine/edge but blade/tang
  17. RX-79G


    Jun 23, 2006
    Thanks, James. I've done it myself, but always assumed that a business would value belts and grind times enough to not want to deal with a fairly wear resistant steel this way. I'm betting that the companies that do this don't even see the blanks until after HT to minimize logistic costs.
  18. james terrio

    james terrio Sharpest Knife in the Light Socket

    Apr 15, 2010
    I'm pretty sure that's true. Even independent one-or-two-man shops do it all the time; it just makes sense. Shipping a few hundred pounds of blades back and forth across the country gets expensive real quick... not to mention the time spent waiting for them.

    The only real downside to using highly wear-resistant steels like 3V in this manner is, there's no way you can afford the time to put a really nice hand-rubbed or mirror-polish finish on them. But honestly most customers don't care about that anyway... certainly not enough to pay much more for it.

    Of course the really big boys order rolls of steel by the ton, stamp the blades, HT 'em, grind 'em, tumble and/or coat 'em, slap handles on 'em, sharpen 'em, package 'em... the steel never leaves the building until it's in a nice pretty box ready to go to the retailer. It's all about efficiency. :) You can find lots of videos from TV programs like "How It's Made" that show the whole process in 15 minutes.
  19. rodriguez7

    rodriguez7 Gila wilderness knife works

    Feb 1, 2009
    Thanks for all the replies, maybe I just need to get James to make my one out of 3v!!!
  20. james terrio

    james terrio Sharpest Knife in the Light Socket

    Apr 15, 2010
    Thank you for the vote of confidence! I am not currently accepting custom orders. :)

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