Downsides to Pivot Bushings? Why don't all knives use them?

Discussion in 'General Knife Discussion' started by bvo85, Aug 15, 2017.

  1. bvo85

    bvo85

    463
    Apr 27, 2017
    Other than cost and high skill required of manufacturing, what are the downsides to pivot bushings? Admittingly, I am a Chris Reeve sebenza fanboy. The upsides of the pivot bushing setup are huge:

    1) Ability to use a "big" "pivot screw", but still use a small pivot fastener that then matches with the other small fasteners on the handle, making them interchangable. When you use a pivot bushing, then the actual pivot size is not just the fastener, but the bushing itself, since that entire diameter of the bushing is what the knife rides on. Having a few completely interchangable fasteners on a knife is better than having dedicated ones for different parts. Also means one tool breaks down the entire knife for cleaning.

    2) Ability to crank down the fasteners to reasonable tight tension, and a perfectly functioning knife without the need for locktite nor risk of the fasteners backing out because you had to loosen the pivot screw to make the opening be smooth.

    3) Smoothness in opening/closing.

    4) Centered blade perfection. The bushing is sandwiched between the handle slabs, which means it's not possible for a properly built knife to have an off centered knife blade. If the bushing is sandwiched by the handle slabs, then the knife can only fit over the bushing in a perfectly centered way. With non-bushing knives, you have to tighten handle screws at different times to get it to reassemble centered.

    There's probably more upsides than I listed. Feel free to add them to the conversation as well. I struggle to think of downsides other than cost due to labor requirements to ensure exacting tolerances. Also, some people on the CRK subforum seem to prefer the non-Bushing CRK folders like the Inkosi and 25, because they prefer using loc-tite on the pivot and being able to adjust the pivot tension to their desire.

    I listed the reverse of this as a "pro" for me but I can respect the opinion of someone who is willing to put in extra maintenance effort to get something that's marginally different to their desire - if you want a really tight or really loose pivot for example, you can control that in a non-bushing system.

    What else are the negative sides of pivot bushing builds? Knife enthusiasts spend thousands of dollars on knives, so higher cost of manufacture doesn't seem like a good enough reason that so few places build bushing knives other than CRK. Mokuti is an expensive material but lots of places are using it, because it looks cool and is in high demand. So either the free market of knife owners doesn't value the pivot bushing, or there's other negatives that I am missing.
     
  2. Zombie411

    Zombie411

    630
    Aug 5, 2017
    The list of negatives is very long indeed.
    First off, they um, sort of... well they a... If you look at um... the uh.
    Well there is the fact that they tend to um,,, kind of a do a strange twisty thing that makes um...

    That's a very good question. I'd love to see the replies myself. I can't really think of a negative other than they MAY wear into the liners or scales or whatever they are supported by.
     
    duffman0500 likes this.
  3. Fanglekai

    Fanglekai

    Jan 7, 2007
    It requires very expensive machinery for tighter tolerances, more stringent quality control, etc. for the bushing, the handle slabs, the pivot hole in the blade and so on. It adds a lot of cost to the manufacturing process. Pretty much the whole knife has to conform to the tighter tolerances or pieces won't fit properly together. In the end if you want CRK tolerances you're going to pay CRK prices.
     
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  4. ExtremAddiction

    ExtremAddiction KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    886
    Apr 12, 2013
    you cant adjust it .
     
    Charlie Mike, kreole and 115Italian like this.
  5. Lapedog

    Lapedog

    Dec 7, 2016
    But the PM2 while a great knife is certainly not built to CRK tolerances, and yet still uses a bushing system quite admirably.
     
    Mo2 likes this.
  6. Zombie411

    Zombie411

    630
    Aug 5, 2017
    I think those are BOTH exaggerated statements.
    Anything (almost) can be adjusted. In fact a bushing that is NOT worn may be easier to adjust/align than a plain pivot. you have twice as many parts to fiddle with.

    The adding to the process is also a bit of a reach.
    You are adding ONE part, and ALL the tooling remains the same UNLESS you are machining the bushing in house. (not likely)
    Supporting the bushing MAY require a modification... .002 cents worth of washers, and a $90,000.00 a year dude to tell an 8 dollar guy where to put them.
     
    Charlie Mike likes this.
  7. Wowbagger

    Wowbagger

    Sep 20, 2015
    zzzzzAKLY !
    quite admirably
    My thoughts as well.
    I have two for two of the little jewels (well not so little) and they WORK (pivot) to perfection as far as what I would ever hope for.

    cough 710 AT $50 more.
    Who said that ? Not me.
    Nope.
     
  8. kniferbro

    kniferbro

    Jan 22, 2011
    The *stepped pivot* that spyderco uses does not function in the same way a pivot bushing ala CRK does. The washers are pinched between the pivot and the liners in the stepped pivot where as the washers are not in a true pivot bushing.
     
    Pensacola Tiger likes this.
  9. Peter Hartwig

    Peter Hartwig Gold Member Gold Member

    Feb 29, 2008
    Others don't use it do to there being a patent
     
    Charlie Mike, JJ_Colt45 and bvo85 like this.
  10. bvo85

    bvo85

    463
    Apr 27, 2017
    Wow!! I did not know this! That would completely explain it then.

    I know of relatively few relevant patents in the knife world. Spyderco hole and Emerson wave. At least the wave has transcended into trademark territory, meaning it's permanently the intellectual property of Emerson Knives, and possibly the spydie hole as well. Anything else have patent/tm restrictions on it other than these three?

    Also, I wonder if when the CRK patent runs out, which it must very soon given how long the sebenza has been in existence, will other knife makers use it at that time? I can't imagine a pivot bushing being permanently trademarkable because it's internal to the knife. Whereas the emerson wave and spydie hole are physical appearances, like trademarking the McDonalds arches.
     
  11. WValtakis

    WValtakis Hand Engraving, Anodizing and Embellishment Knifemaker / Craftsman / Service Provider

    May 29, 2004
    That also explains why my Microtech Vector DID HAVE a pivot bushing, lol.

    ~Chip
     
  12. danbot

    danbot Gold Member Gold Member

    Oct 31, 2009
    How can someone patent a bushing? Is this for real??
     
  13. JB in SC

    JB in SC Basic Member Basic Member

    May 19, 2001
    Pivot bushings are a big plus on slip joints. The bolsters can be very tight to the bushing without binding the blade. Tony Bose has been using them for many years. To my knowledge there is not a patent for this particular type of simple pivot bushing. Scott Sawby has a patent for a locking type pivot bushing (the Sawby Self Lock). Ted Lewis has one for a pivot bushing with a lubrication reservoir.
     
  14. Peter Hartwig

    Peter Hartwig Gold Member Gold Member

    Feb 29, 2008
    I guess the same way Spyderco was able to patent a hole :)
     
  15. danbot

    danbot Gold Member Gold Member

    Oct 31, 2009
    Haha! Good one!

    Just wondering because where I work we make step bushings and bushings with lubrication grooves in the I.D etc. for many different company's applications and they are just components for all kinds of different engineered designs. Sometimes we make them and sometimes they are purchased, but even most of the purchased ones are not patented.
     
    lieferung likes this.
  16. traumkommode

    traumkommode Gold Member Gold Member

    Dec 3, 2015
    With knives like Bose, he makes them by hand and can tune them any way he wishes. They also cost $2000+, so rightfully so. Spyderco can't afford to do that on every knife they made. The PM2 has a cool pivot, but the one's that aren't right just don't have nice action. So it's not really comparable to the CRK pivot bushing. It's an extra part and extra work that probably doesn't seem worth it, especially when a majority of knife users likely aren't on BladeForums.

    Washers (phosphor bronze) make the biggest difference to me. CRK has very expensive equipment and a lot invested in making a few patterns to very tight specs. Benchmade or Spyderco can't offer the diversity in models that they do and afford to have such refined equipment. I've seen a production factory where they have machinery like that. Each machine costs easily $250K to $500K, some even more.
     
    Charlie Mike likes this.
  17. Peter Hartwig

    Peter Hartwig Gold Member Gold Member

    Feb 29, 2008
    ^^^ up one post
    I don't know enough about patents to give a good answer, but it may not only have to do with just the uniqueness of the pivot bushing, but also the uniqueness of the pivot bushing to the application.
    Hopefully someone with a fuller knowledge can clarify this.
     
  18. vwb563

    vwb563 Gold Member Gold Member

    Jun 29, 2007
    I would have to say their main negative is added production cost. Especially in a knife where they're not really needed like an assisted opener.
     
  19. lieferung

    lieferung

    May 24, 2016
    Knife parts newbie here. What's a bushing?
     
  20. danbot

    danbot Gold Member Gold Member

    Oct 31, 2009
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