CPM3V vs CPM4V

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by gsx-rboy750, Oct 7, 2014.

  1. gsx-rboy750

    gsx-rboy750

    356
    Jul 3, 2014
    I am pretty sure they charge a cut fee.
    I am going to try to avoid getting strips shear cut the width of what I am working on. I think the shearing actions weakens the edges of the steel. I also think you get some very slight bends in the metal especially in thin widths and thicknesses.
    The last piece i got was a 11by 17 cut on a band saw. I think having them jet them is the hot ticket.
     
  2. numbersman

    numbersman

    577
    Nov 28, 2010
    I clearly don't understand what is meant by a flex test here, if you guys are talking about a 50 degree flex. Are you sure you don't mean a 50 MINUTE bend?
     
  3. gsx-rboy750

    gsx-rboy750

    356
    Jul 3, 2014
    I was referring flexing the knife I made past 50 degrees. I did it many times and personally I caused some damage.
     
  4. gsx-rboy750

    gsx-rboy750

    356
    Jul 3, 2014
    Well over the past couple weeks/ month I got my Zwear back from heat treat at 60RC and it seems pretty dam tough and pretty dam hard as far as retention and scratches.
    I also bought some 3V to do a big chopper, PD-1 for making a simular blade to the 3v and zwear K have and some cpm4v to stack against the three as far a retention.

    I can say out of the PD-1, zwear and 3v the PD-1 is the toughest to cut and machine in the annealed state.
    The zwear at 60 seems harder in relation to edge holding then my 3v at 61rc.

    Nothing scientific but my observations so far.
    I am using the 4v for three kitchen knives and a smaller edc fixed which I will have a simular 3v to do a direct comparsion.
     
  5. Lo/Rez

    Lo/Rez

    Feb 10, 2013
    That's interesting that the PD#1 is the hardest to work with. I have a Strider SMF with a stonewashed PD#1 blade and really like it.
     
  6. jdm61

    jdm61 itinerant metal pounder

    Aug 12, 2005
    My initial experience with 3V was that it gets HOT fast when you grind in the annealed state. I don't recall it being any worse hardened when I was obviously watching it much more carefully.
     
  7. gsx-rboy750

    gsx-rboy750

    356
    Jul 3, 2014
    I am not following 100%?
     
  8. tatalley10

    tatalley10

    57
    Nov 29, 2015
    Ok I have read this entire thread. I feel like cpm4v is still a mystery other than paper statistics. And according to bar graphs one losses much toughness to gain not so much edge retention (hardness among other things being equal).

    it's hard to compare different metals with different heat treats that are not manufacturer recommend hardness without making a 100 knives all slightly different heat treated (ground and sharpened the same) then testing all of them methodology in the same tests. Which nobody has time or $$$ to do.

    I am newer to knife making and want to make some knives like 3 river blades tests on YouTube where they pound a cpm3v knife into a steel plate with seemingly no edge damage!!! My mind was blown watching over a 1000lbs on the handle and the blade didn't break and snapped back straight...
    it seems to me that cpm3v is better suited for the aforementioned type of knife than cpm4v, right? At least on paper...

    Anybody out there do any testing on cpm4v like the youtube video from 3 rivers blades?
     
  9. tatalley10

    tatalley10

    57
    Nov 29, 2015
    I see no replies... hrmmmm
     
  10. bodog

    bodog Banned BANNED

    Dec 15, 2013
    I didn't video it but I have a couple if blades in 4V at 62 RC, right down the manufacturer's recommened process. I was able to cut through packing staples, nails, little metal statues, etc. Did it on a concrete floor where the edge went right into the concrete floor after cutting through the other stuff.

    Barely any edge deformation except right where the metal crap I was cutting went through and it was only a tiny bit. Very small dents.

    In hindsight I should've had the spine thinner with a flat grind instead of hollow. The spine is right about .200" with pretty deep hollow grinds down to about .025" behind the edge. Sharpened to 20 degrees per side.

    Cuts a long time and no worries about chipping or breaking but it binds a lot in deep wood as you'd expect. I hammered the crap out of my test blade with only a few dents in the spine and a couple of places where the butt chipped when I hammered it straight through some wood. I was far harder on it than I'd ever be in real life use and it stood up fine. .187" or a little less with a flat grind down to about .015" behind the edge sharpened to about 15 or 16 dps would most likely suffice for all but the most punishing work. The hardness could be inched up from 62 to probably 63 or 64 and still be good to go for most people.

    It's a bitch to sharpen though. One of the hardest I've messed with and that includes several really high carbide volume steels. I actually made a thread asking why 180 grit silicon carbide stones were giving an almost mirror finish on this steel. I've never seen anything like that before, even on rex 121 at 68 RC. Granted, the rex 121 blade was harder to sharpen but it didn't burnish from the stones.
     
    Last edited: Mar 1, 2016
  11. tatalley10

    tatalley10

    57
    Nov 29, 2015
    So 3/16 full flat with a second bevel 20 degrees around 62rc, would give a good blade but how deep would the blade need to be to give the best strength versus utility? 1.25, 1.5, or 2"???
     
  12. bodog

    bodog Banned BANNED

    Dec 15, 2013
    I guess it'd depend on the design of the knife but the one I have is just a little wider than 1" and seems fine to me for what I need it for. It seems to be a pretty well rounded steel. The ones I have haven't rusted yet. Taken thin and hard it stands up to almost any other steel or make it thicker and you have to really be thrashing it to get it to break. It's not the best in a single category but it seems capable of a number of uses based on the design.

    And there are a lot of people with far more knowledge than I have, I'm only speaking up because not many others are.
     
    Last edited: Mar 1, 2016
  13. tatalley10

    tatalley10

    57
    Nov 29, 2015
    I want to create 3 designs. One that is EDC tough enough for fire/rescue/ER NURSING, a second for bushcraft, and a third for larger thumping and survival needs... kind of a small medium and large size. Lol
    I was thinking 1.5"x3.5"(blade)x3/16" small
    1.5"x5.25"(blade)x3/16" medium
    2"x8.5"(blade)x3/16" large
     
  14. tatalley10

    tatalley10

    57
    Nov 29, 2015
    Cpm3v seems to be able to fit all of these needs other than not being friendly to field sharpen for bushcraft. I see no real advantage for using cpm4v? Does anybody else?
     
  15. Lo/Rez

    Lo/Rez

    Feb 10, 2013
    I don't see any advantage, but I'm far from the most knowledgeable one here. I would say try 1/8" for your small and medium knives. Better cutting geometry.
     
  16. tatalley10

    tatalley10

    57
    Nov 29, 2015
    I was thinking the same thing for the medium. But the small one I want to be a bitchen, sharpened pry bar, I was toying with doing a hollow grind on the small...
    Scandi on the 1/8 to 3/16 inch medium
    And a full flat on the large...
     
  17. Darrin Sanders

    Darrin Sanders Knifemaker Moderator

    May 6, 2009
    I much prefer 4V to 3V. The toughness of 3V is overkill. Kinda like shooting squirrels with a .375 Mag.. Yeah it'll do the job but isn't needed. 4V is plenty tough enough especially in smaller to medium sized knives. Oh, and keep this in mind, I grind my knives THIN and run them HARD.
    I've driven a 10V/A-11 blade .080" thick and ground to .010" thick behind the edge through seasoned, cross grain, Osage Orange/Bois d' Arc & Axis stag antler with no damage. Just a small shiny spot after the antler. That's tough enough for any job a small to medium knife will need to so. I'm telling you guys, toughness is WAY over-rated in knives.

    Edited to add that the 10V blade was at 63 RC.
     
  18. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Just to point out something to bodog and tatalley .. this is more than a year old thread.
     
  19. tatalley10

    tatalley10

    57
    Nov 29, 2015
    Imagine that, a year and no real solid scientific info or a lot of real world use... I am interested in the difference between the metals but can't find a lot of info from a testing point of view. Hen c e why I posted and asked. Do you have any info to help me on this quest
     
  20. Ankerson

    Ankerson Knife and Computer Geek Gold Member

    Nov 2, 2002

    I have tested CPM 4V and it's VERY strong, more than strong enough that most couldn't tell the difference in 3V and 4V in MOST uses.

    The problem is there aren't enough makers working with it yet to get a enough data points.

    That will change however in the future as more makers work with it.
     

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