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Folder design with best lateral/prying strength

Discussion in 'General Knife Discussion' started by Thereisnocowlevel, Dec 22, 2019.

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  1. T.L.E. Sharp

    T.L.E. Sharp Freedom for @Fullflat!!! Platinum Member

    Jun 30, 2016
    So you need to be a long standing member of the forums for me to expect some measure or logic or reason from you? I'm not ridiculing you. I'm ridiculing your silly idea. @knarfeng would've received the same responses and he's got the authority to ban me. I also don't offer my sharpening services to the general public anymore. Books have been closed for some time now.

    Using a knife daintily and using a knife responsibly aren't the same thing. Cold Steel is more than fine with you hacking at tree limbs or stabbing oil drums with their knives. Not exactly dainty use. I wouldn't do either with my knives.
    Last edited: Dec 23, 2019
  2. DocJD


    Jan 29, 2016
    Not "most" . Cold Steel . I suggest you buy a 4Max and do some prying . It might surprise you ! And it can also do knife stuff .
    insta9ves and craytab like this.
  3. stabman

    stabman Gold Member Gold Member

    Sep 17, 2007
    MOST folding knives, even those marketed for "hard use" ship with paperwork saying not to pry with them.
    Or throw them.

    Prying and throwing are not considered valid knife usage by most knife manufacturers.

    People are free to use them however they wish after they buy them, but manufacturers are pretty clear about their position on the issue.
    Lance Leon, James Y, craytab and 2 others like this.
  4. mtbaddict


    Jan 5, 2014
    Up until very recently I was outdoor recreation professional, and half the year that means I was a kayaking instructor. I just about lived in a PFD where I had limited room for the tools I need to carry, and one of those has to be a knife. There's a big debate in the river guide community about carrying a fixed blade with a blunt tip (due to the need for us to pry some things off rocks, but still need to cut rope and possibly a boat) or a folder. I fall on the side of the argument that if you were to loose the knife off your vest you don't want a live blade cruising around in the water in an emergency situation that could cut you or a victim, hence I carry a folder on me that I have to depend on.

    For years now I've carried a benchmade triage, and I feel like torsionally and laterally it's about the best thing I can find. The axis lock isn't going to disengage very easily if you twist the knife. I recognize this question is about prying, but I've found in my career as a guide and as a bike mechanic that if I've got to pry something I'm probably going to be twisting it to. Frame locks can very easily be twisted off the lock surface on the tang, I've had that happen to me in a high stress environment before, and it's pretty dangerous. The triage also has benchmade's version of a solid pivot, the male screw goes through the entire female side and almost exits outside of the knife. It's also got full steel liners, for my purposes they help resist those lateral forces. Obviously I know it's far from indestructible, and is an emergency use tool, but when that's all you got...that's all ya got.

    My final disclaimer is I'd much much much rather use a pry bar, crow bar, or a breaker bar to move some of things I have to move, but those just aren't an option to carry with me on the boat. I'm pretty jealous of anyone that has a vehicle that can carry the optimal tools for the job.

    I hope this input helps, even if your question was just a thought experiment.
    DocJD and Thereisnocowlevel like this.
  5. Danke42


    Feb 10, 2015
    Oh good point. I want to be able to throw that knife too!
  6. Natlek


    Jun 9, 2015
    They are arguing with reason . Look , most folder knives today have high hardness blade from stainless and are so called super steel , steel like M390 .And I don t think that this steel is good for prying .You can make folder which will resist lateral forces , but that will not help in prying at all .Frame will hold but blade will break . Even if you have fixed blade in same steel and hardness that knife will snaps if you try to pry.
    Again , it can be done for sure .Prying folder knife , make it from tough steel like 5160 in appropriate thickness of steel and it will work . I would like to see how someone break 4 inch blade with 4-5 mm spine thickness from 5160 steel with hand :)
    My I ask you one question ?
    Incidentally, I have two knife. Same shape , same dimension ,same steel . One is folder one is fixed blade .What do you think if in a name of science I make test and try to pry with them .Which one will survive ? Both will break only if i think to do that , no matter that one is folder and one is fixed ....HSS steels don t like to bend at all .My point is there was a reason why manufacturer of pry use steel they use ...Can you make pry bar from CPM 125 V or from Maxamet steel ? So it is more about steel not about design......that is my opinion about what you ask :thumbsup:
    My twins ........pry bar :)
    ErocSD, Mecha, herisson and 2 others like this.
  7. Thereisnocowlevel


    Nov 7, 2018
    Those are two beautiful knives btw. I have to clarify again we are not attempting to design a prybar folder dedicated for prying but rather to improve the common folder design to make it resist lateral folders better.

    I am also not focusing on the blade material and geometry. Yes that has effect on prying strength but there is already so much discussed in fixed blade designs. Trying to stay on the topic of folding mechanism design. Features like mtbaddict mentioned above like Benchmade’s pivot construction, hindere stop pins, one piece rolled steel frame, larger washer etc. Elements unique to folders.

    In direct answer to your question yes of course both will give out, BUT if you state that your folder has just as much lateral strength as your fixed blade I would like to know how. If the blade snaps or holds up etc that’s a topic for fixed blades designs. Just the folding mechanism part which unique to folders.

    And I want to say in earlier post you have mentioned design elements that make your folder resist lateral forces, like beefed up frame/scales and forgoing the shim and detent ... and those are the things that pertain to the OP.
    Natlek likes this.
  8. herisson

    herisson Apple slicing rocking chair dweller Platinum Member

    Mar 11, 2013
    Friction folder, 0.5" diam. bolted through pivot, one piece handle milled out of 5160, or 1065 (for example), long extended massive tang that embeds in the handle when the blade is open. It will be a brick in the pocket (but you can carry it in a belt pouch) and you should be able to pry all your heart's content without ruining the knife (if the blade is as strong as the handle).
    Thereisnocowlevel and Natlek like this.
  9. Natlek


    Jun 9, 2015
    Look , scale are 2.5mm HSS steel they are permanently riveted ,carbon fiber scale is glued with epoxy + that two pins are peened .Pivot is 6mm ...All that make frame stiff and blade will fall first .3mm beveled steel against in total of 5mm flat steel + carbon have no chance ...i think
    Mecha likes this.
  10. herisson

    herisson Apple slicing rocking chair dweller Platinum Member

    Mar 11, 2013
    This caught my eye on the fly, sort of...

    In your post #44 [Hmm you mentioned wide washers how would that work? Distribute the force at the tang?]

    Really ? This is a question to you who asks others to think "out of the box" ? Seems you have a lot of "in the box thinking" to do before you challenge professionals to step up to what is at best a very special need, and at worst some geek phantasy.

    If you are actually interested, and this is the most basic of practical mechanic knowledge : it spreads the forces on a wider surface around the pivot (on the tang, the scales and the handle).
    Mecha, lieferung and James Y like this.
  11. kniferbro


    Jan 22, 2011
    Metal handles, wide/large surface area washers, big pivot with wide heads, and thumbstud blade stops
  12. GatorFlash1

    GatorFlash1 Gold Member Gold Member

    May 28, 2012
    You might just want to grind an edge on a crowbar. That solves the problem.
    Mecha and lieferung like this.
  13. herisson

    herisson Apple slicing rocking chair dweller Platinum Member

    Mar 11, 2013
    But please grind it thin, for slicing ability. Wait, wait...
  14. Steely_Gunz

    Steely_Gunz Got the Khukuri fevah Moderator

    May 9, 2002
    Sounds like a Svord Peasant married to a Pocket Bushman style handle. If the handle was as wide as a PB, then that extended tang could be 1/4"-1/2" wide and 2-3" long depending on how comfortable you are trying to make the knife to carry. Back end of the tang could be made with a rounded cut out and mate over top a thick through pin made of some desirable material. I guess the tang would have to seat into a milled channel on top of the grip if it were to behave like a Peasant. Sandwiched between the steel of the handle in the channel, if it had a proper fit, and the strength of the length of the tang running down to the stop pin, and the mechanical fastener's strength at the pivot, and I bet you could make a folding prybar with a 4-5" blade that would absolutely suck to carry.
    Mecha likes this.
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