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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. Peter Hartwig

    Peter Hartwig Gold Member Gold Member

    Feb 29, 2008
    Thick tip and blade will help some. No folder is really made for prying, but being robust will resist snapping off a tip some . Most seem to break at the thumb stud or spyhole(or generic version), if not the tip ,so maybe a robust flipper. Better yet a replacement no matter what you do warranty.
    Myself I would rather use a knife for cutting and pick up a prying tool for prying-right tool for the job
     
    DB_Cruiser and Edgeoflife like this.
  2. Thereisnocowlevel

    Thereisnocowlevel

    29
    Nov 7, 2018
    Yes for the manufacturer and yes for the consumer. People on blade forums definitely have equaled toughness to vertical lock strength alone. I would definitely be interested if they could offer a 200% stronger lateral force design.

    As to how much cutting performance am I willing to compromise? Quite a bit actually. And that has also been shown in the fixed blade market with the likes of bk2 and esee 5, sacrifice slicing for prying chopping batoning.

    With that said I believe there are ways to increase lateral rigidity without significantly compromising cutting or folding smoothness. For instance having external stop pins/thumb studs bracing against the frame, that design feature resists lateral forces and reduces prying force on the scales
     
    Last edited: Dec 22, 2019
  3. Thereisnocowlevel

    Thereisnocowlevel

    29
    Nov 7, 2018
    Also guys I just want to clarify...I am not talking about tip strength or blade geometry, rather the lock/frame construction
     
  4. tomhosang

    tomhosang

    250
    Feb 17, 2017
    I can't believe nobody has mentioned it yet, but the big blade stops on an XM-18 should help it resist lateral force.
     
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  5. benchwarmer380

    benchwarmer380 Valyrian Member Platinum Member

    Sep 17, 2012
    But you are.

    What good would the strongest lock and frame be if it was paired with an Opinel's blade?

    If you're designing for a specific purpose then all aspects must be considered or it will fall short of the goal.
     
  6. Thereisnocowlevel

    Thereisnocowlevel

    29
    Nov 7, 2018
    Exactly! Thank you for mentioning! We need more design features like this
     
  7. Thereisnocowlevel

    Thereisnocowlevel

    29
    Nov 7, 2018
    We can discuss it but it’s not that different that what has already been discussed for fixed blades. The frame and lock design is the main challenge for a folder

    With that said is there anything on the market that resists lateral forces better than the stop pins against frame on the hinderer?
     
    Last edited: Dec 22, 2019
  8. Edgeoflife

    Edgeoflife Gold Member Gold Member

    Oct 11, 2018
    While i dont pry with my folders, external stop pins and large washer pivot systems will help with strength against lateral forces along with a robust tip of course.
     
  9. lieferung

    lieferung Basic Member Basic Member

    May 24, 2016
    The reason lock strength and vertical force is talked about is because it directly relates to the function of the knife. If a knife lock cannot resist an amount of vertical force it has a risk of failing, resulting in injury to the user. Lateral force is not talked about because it is not related to the function of the knife, a knife is not intended to be pried with.
     
  10. Thereisnocowlevel

    Thereisnocowlevel

    29
    Nov 7, 2018
    Lateral force is very much talked about in fixed blades. Why should folders get a pass? Especially since manufacturers tout their toughness or locks being “virtually” a fixed blade.

    Understand it’s not a pry bar. But there’s nothing wrong discussing features that make a folder strong laterally
     
    insta9ves likes this.
  11. Crikeyyy

    Crikeyyy Basic Member Basic Member

    552
    Dec 14, 2019
    Tom brown tracker is a good prybar knife, since its a thick slab o steel.

    It has awful cutting and slicing ability, awful chopping ability, useless serrations, but pry-power is excellent I bet
     
    lieferung likes this.
  12. Steely_Gunz

    Steely_Gunz Got the Khukuri fevah Moderator

    May 9, 2002
    We can discuss this indefinitely, but the fact remains that a folding knife's vertical blade play can be boiled down to two criteria: Safety and Performance. A knife with a good deal of vertical blade play or weak lock up can slip its lock and fold on your fingers. This is why Lynn Thomson's guys make a big deal about doing pull ups on the knife to test the lock strength. A knife with a good deal of up and down play may disengage the lock. A blade wiggling from side to side would bug me a great deal. A knife snapping shut on me when it's not suppose to could ruin my day.

    As for performance, this gets into the weeds of perception. Vertical blade play can make a knife "feel" like it's not doing the cutting job or requires extra effort. OTF autos have more blade play than would be acceptable for most knives simply due to the design. A $300 Microtech does not lock up as tight as my 12 year old $70 Endura. However, it is baked into the design. My Microtech cuts just fine, but when I bear down on it, I can feel it move a smidge.

    There is actually a thread about blade play on the CRK forum. Probably the most exacting production knives out there in most regards. I believe someone mentioned a tolerance of .0005 or some such to account for the grease between the tang and washers. My Inkosi is dialed in to be smooth to open and close with no detectable up and down play and only the faintest side to side if I flex it hard enough to cut myself (which I did). I can crank it a touch tighter and it doesn't budge in the least. Maybe in a vice, but not using my arm strength. However, when I do that it opens like a wooden door with water damage.

    I'm not sure you can reinforce a folding knife enough to make lateral play go away to the point where it is both undetectable and doesn't hinder the function of a knife. A solid frame of expertly milled and finished titanium using a ceramic bearing and washers tightened down by a big ol stainless screw and bushing comes about as close as I have held to "zero" lateral play.
     
  13. Alberta Ed

    Alberta Ed

    Jun 29, 1999
    Most are actually pretty stout but not the best for prying. Emerson may be the strongest - they seem designed for abuse.
     
  14. stonproject

    stonproject

    Nov 22, 2013
    A balisong would probably last longer prying than a typical folder but it would still be a bad idea. If I have to pry something I definitely don't reach for a knife.
     
  15. Thereisnocowlevel

    Thereisnocowlevel

    29
    Nov 7, 2018
    I would also add that a knife with little lateral strength is also a safety concern. If the frame comes apart due to lateral force exerted on the blade, it will also compromise the lock that is preventing it from closing on your fingers. Most locks need the scales/liners to be “sandwiched” in place to work

    I am not hiding the fact that I want to break down this type of thinking that manufacturers can tout a knife as tough by focusing only on vertical strength.

    And here’s my question: when you exert 100lb + of vertical force on a marketed hard use folder, in real life, wouldn’t there be a considerable lateral force exerted on that blade due to imperfect technique?

    When you stab very very hard wouldn’t there be also be a considerable lateral force?
     
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  16. Steely_Gunz

    Steely_Gunz Got the Khukuri fevah Moderator

    May 9, 2002
    If you are putting 100lbs of vertical force on a folding knife, in my opinion, you are doing one of two things: A) using the wrong tool for the job. Forcing the knife to work outside of its parameters instead of getting a stronger tool with more leverage that will do the same work with less effort. Which is just dangerous. Or B) frantically cutting/prying yourself or someone else out of a dire once in a lifetime event where thrashing the tool is the quickest/best option. It's not what the life is going to be doing for a living, it's just what you can reach in an emergency.

    I still see lateral play as a prying issue which up to the end user to decide if that's something important they need in a folding knife. I have seen lateral tests where the blade lock up and scales flex sideways in a vice with a cheater, but this was shown how durable the knife was constructed and how much abuse it would take and pop back into spec and had nothing to so with attempting to limit said play.

    Thinking of a knife that can fold and nearly behave like a fixed blade, the one that comes to mind is the Cold Steel Pocket Bushman. Once the RAM is engaged, there really isn't anywhere for the blade to move. The whole handle is rolled steel. So you have a solid piece of steel plunging into the tang and a monolithic grip. It might cut your fingers off when you try to close it and have the ergonomics of a piece of angle iron, but it's pretty solid.
     
    Last edited: Dec 22, 2019
  17. DocJD

    DocJD

    Jan 29, 2016
    Cold Steel folders with the Tri-ad lock are probably the overall strongest of any practical and affordable for "hard use" .

    Their 4Max would probably do pretty good in any reasonable test . But most people don't want to carry something even that beefy for EDC .

    To get increased lateral strength you'd have to go thicker and the market demand seem to be going opposite .

    I consider the question to be perfectly valid and interesting .

    So far as stabbing , if you mean flesh and blood , you don't need extreme strength for SD use . But you do need a lock that will stay locked = Tri-ad .
     
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  18. lieferung

    lieferung Basic Member Basic Member

    May 24, 2016
    I don't know what kinds of things you want to use a folder for, but as Steely said it sounds like you're using the wrong tool. Folders marketed as "tough" are not do all indestructible, they are relatively tough compared to folders in general. And they certainly aren't fixed blade replacements, or prybar replacements for that matter.
     
    benchwarmer380 likes this.
  19. blanex1

    blanex1

    Feb 11, 2015
    I wouldn't try prying with any folder! but found the large pivot pin in the Inkosi along with CRK's excellent tolerances on titanium handles makes a Wonderfull work knife, absolutely no side to side movement what so ever, but most people would use a Crowbar for prying things.
     
  20. DocJD

    DocJD

    Jan 29, 2016
    Folders have maintenance and sanitary concerns that also make them less popular for hard use / survival .

    Fixed blades are cleaner and less costly at any given level of performance .
     
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