Ball Bearing pivots actually weaker than PB washers?

Discussion in 'General Knife Discussion' started by Gideons, Dec 23, 2017.

  1. DocJD


    Jan 29, 2016
    I'm not qualified , either . But , wheels can turn corners . Bumblebees can fly . The very expensive Russian maker probably knows something we don't .
  2. Danke42


    Feb 10, 2015
    The very expensive Russian maker knows that a lot of people have excess money that the maker would like to take from them.

    Coming next; differential bearings for those worried about scuff.
    DocJD likes this.
  3. Cobalt

    Cobalt Gold Member Gold Member

    Dec 23, 1998
    Pretty logical for someone who is not an expert. IF you look at typical thrust bearings you will see the outside diameter is a bit bigger to compensate for exactly what you are talking about. Problem is that you cannot do that for totally flat bearing. It would make the assembly to thick. With knives it isn't a big deal because the rotation is minimal. 180 degree rotation max.

    DocJD likes this.
  4. Gaston444


    Oct 1, 2014
    Either the inner side of the roller rod will skip by "braking", or the outer side will skip by "accelerating". Possibly a bit of both all the way through. There is no rubber here to take up the slack, so it definitely is pure friction that will take over, at least in a part of the roller...

    I guess the rollers (for a flat-type pivot) should be split in 2-3 short portions, as long one-piece rollers don't make a whole lot of sense, friction-wear wise...

    DocJD likes this.
  5. DocJD


    Jan 29, 2016
    I can easily imagine some huge honking thick tank knife equipped with THRUST bearings . Even sounds cool ! :cool::thumbsup:
  6. Chefget

    Chefget Gold Member Gold Member

    Nov 2, 1998
    Nope, simple physics

    The further out from the center of a rotating circle the greater the distance travelled for a given degree of rotation
  7. Officer's Match

    Officer's Match Gold Member Gold Member

    Jan 23, 2013
    My concern with bearings is the open windows for grit that comes along with the prospect of a folding pocket knife.
    DocJD likes this.
  8. stabman

    stabman Gold Member Gold Member

    Sep 17, 2007
    Well, I scientifically cut open some boxes containing scientific equipment with the ZT 0561. :)
    The bearings did not fail while cutting the tape. ;)

    You cannot beat data of that magnitude! :D
  9. DocJD


    Jan 29, 2016
    Can't bearings be sealed ? They should be for dirty work .
  10. Cobalt

    Cobalt Gold Member Gold Member

    Dec 23, 1998
    Yes, but it would make a knife unworkably thick. Think of a skateboards bearings which are sealed cartridges and they are at least 1/4" thick. That would make for a very thick knife.
    W. Anderson and DocJD like this.
  11. DocJD


    Jan 29, 2016
    There's probably a way to scale down that thickness some ? Anyway somebody must buy those tank knives . Medford and such .
  12. shinyedges

    shinyedges Unfaltering Love & Undeviating Will Knifemaker / Craftsman / Service Provider Gold Member

    Jun 5, 2012
    Open spaces let stuff in.... and out. Look at glocks.
    W. Anderson likes this.
  13. Steely_Gunz

    Steely_Gunz Got the Khukuri fevah Moderator

    May 9, 2002
    My 909 has been dropped in mud, kept in a pocket that constantly fills with dirt, and denied oil for weeks at a time.

    Never an issue with the bearings locking up. I might give the pivot a rinse if it gets caked, but the 909 works regardless.
  14. singularity35


    Mar 1, 2010
    Not having made a study, I don't know. Not having used a roller bearing knife, I don't even have an opinion. But the question was "which is stronger?".

    I don't have an answer but I am curious what the answer is. Unlike some folks here, I don't know or pretend to know everything. ;)

    See? That's what I said. Nobody is even trying to answer the question but all kinds of verbal gymnastics are being presented just to avoid an actual answer.

    I'm guessing nobody wants to know the answer.

    I'm out.
    Last edited: Dec 24, 2017
  15. shinyedges

    shinyedges Unfaltering Love & Undeviating Will Knifemaker / Craftsman / Service Provider Gold Member

    Jun 5, 2012
    How the hell can we decide an answer with out actually conducting tests to know which is stronger?

    Extreme side loads will likely cause damage to a washer, they are not crush or deformation proof. Hell I don't know, the answer is a usual.. it depends lol

    Even if a washer is crushed or damaged the knife will likely still function, same as if the bearings indent the titanium the knife is still functional.

    I see the Philippines is getting hammered with a storm on the news. Hope you and yours are well.
    DocJD likes this.
  16. singularity35


    Mar 1, 2010
    I guess that's the bottom line. I'm still curious though.

    Another question for that is which of them will fail sooner with the same amount of damage.

    Yes, it was headed our way but luckily we dodged the bullet when the track changed almost at the last moment. The storm killed around 100 people at last count.
    DocJD likes this.
  17. shinyedges

    shinyedges Unfaltering Love & Undeviating Will Knifemaker / Craftsman / Service Provider Gold Member

    Jun 5, 2012
    I'm curious too, I have both washer and bearing knives. But I'm not going to destroy one of my bearing or washer knives for this thread. So, opinions will have to do :p

    Good to here it changed course, I'm from Florida and grew up with hurricanes. The news/weather people can predict the path to an extent but big storms are unpredictable.

    I've seen first hand what a roof ripped off is like.
    DocJD and singularity35 like this.
  18. DocJD


    Jan 29, 2016
    This sound most plausible to me . So my "simple" WAG answer to the OP = YES !
  19. dsalazar


    Jun 22, 2017
    Correct me if I'm wrong but I thought the whole point of bearings or washers in a knife is for smoother opening. I can see how it can be a weak point in a knife design. I feel as though the blade would break before a washer/bearing fails.
    DocJD likes this.
  20. Knife Outlet

    Knife Outlet

    Jan 4, 1999
    I don't know that ball bearing pivots are weaker. But I do know that they are strong enough to handle the things a properly used folder will encounter.
    Mo2, DocJD and Cobalt like this.

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