viper carnera chipping

Discussion in 'Knife Reviews & Testing' started by Drakul Mihawk, Dec 6, 2016.

  1. Drakul Mihawk

    Drakul Mihawk

    26
    Jan 4, 2014
    I was chopping a nice 7-inch olive piece cut two months ago when it was almost gone the viper carnera blade crumbled. I was doing or rather trying to make a video review in English to be published on youtube of viper when it happened, so I have all recorded on video.

    From what I understand now, the viper is a small machete, a laser on the vegetation and the green wood of small size, however, is it not suitable for chopping large pieces of dry wood in general. The full-flat grind, the d2 steel, a thickness on the edge around 0.6-0.7 mm, do not perhaps make it suitable to be a field knife. Or maybe it was a bad heat treatment, but I do not believe, or at least the only one who can judge with certainty is the viper that has the tools and knowledge to do so.

    There is also to say that when you get to the center of a large piece of wood, on the blade of the discharge side of absurd shear forces, so it is easier to break it on these occasions.I do not like to see on youtube video rewiew when they give 10 strokes with a chopper and then analyze the damage to the wood, because first point: to see a big difference one of the two must be a crap or either an amazing knife, with only 10 shots, often bad data, you will not see a big difference between two knives; second point: the blade is not placed under stress minimally, with only 10 shots, there is the bark tree, which is the soft part of the wood.

    Another consideration i would make is that the best grind for a field or a chopper knife is a saber with convex edge. If you make a full flat you must have the right steel, for example forged carbon. For industrial knife one goes more on the safe side with a saber and not too high, but not low (ok relatively safe):cool

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    This is the video, the blade is destroyed into pieces after the minute 14:30, sorry for my bad english guys, but at least we have the video.

    [video=youtube;z7vaZIjeb3o]http://www.youtube.com/watch?v=z7vaZIjeb3o[/video]
     
  2. bluntcut

    bluntcut KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Apr 28, 2012
    I scanned your video - big chip on this chop http://youtu.be/z7vaZIjeb3o?t=14m57s
    Edge deflected so bevel & blade bend sideway - then edge/apex impacted wood, forces concentrate along bend perimeter, resulted with big massive fractured/chipped.

    Thin FFG D2 blade is a poor choice for chop & impact cuttings. Wrong geometry is key here. A 1075 machete with this geometry would probably suffer massive ripple/bend as well, although won't be as bad as D2 chipped size. Ht wise - a softer D2 would slightly ripple/plastic on first strike, subsequent poor strikes would end it. Steel material strength & toughness are different among ht at linear scale, while geometry/volume is cubic, therefore first select appropriate geometry for tasks & technique. With good ht & steel, you can then reduce/thin geometry accordingly albeit reducing at cuberoot rate.

    e.g. a magical 2x ductile & stronger steel, geometry can be maximum reduce by 25%. btw - strength differences usually within 10-20% among ht steels. This is why, I state ^ 1075 also will suffers damage with thin ffg geometry because ductility alone just plastic/move steel around, need strength to resist bending. Ductile+strength usually result in higher impact load <= this is the impact toughness you want for chopping/impacts usage.
     
  3. arty

    arty

    Oct 18, 2003
    I would rather have 1095 with a proper heat treat and geometry or 1085 than D2 for a heavy duty chopper. D2 is not a very tough steel. Of course geometry matters, as does heat treatment. For really big blades, you can't go wrong with carbon steel without all the chromium you get in D2.
    I have a Kabar Parangatang and I had to accidentally hit concrete landscaping bricks to get any chipping of the edge, and it was nothing like in the D2 blade. I was able to easily grind the chips out with my 1X30" belt sander.
     

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