Drop-shut: Optimal lubrications / modifications?

Discussion in 'Maintenance, Tinkering & Embellishment' started by Stwida, Apr 3, 2020.

  1. Stwida


    Feb 12, 2020
    Recently invested in KPL and KPL Heavy, aplied them to my knives, and really didn't notice any difference in action quality. Maybe some "sandiness" has decreased, but really nothing significant, only marginal. So, a few questions, just to make sure my understanding is correct...

    When an action is "sandy" or "scratchy":
    What is this? What causes this? I have a few knives that are very "gritty" (when you move the action open and closed, you hear it), but still offer a good action. Whereas I have a ZT that literally feels like polished glass riding on polished glass. Makes no noise, no friction. Is the "sandy" sound / feeling inherently good / bad? Can it be made to mimic the ZT's "glassy" action? If so, how?

    Regarding lubrication:
    Is wet the best? Dry the best? Difference in optimization in different action systems (bearings vs washers)? I know "the best" is often subjective and inherently has a "it depends" kind of answer... but if I add the restriction of optimizing action, maybe that helps answer the question. For what it's worth, my favorite actions have bearings, and that's what in most of my knives.

    How to modify a knife to make an action better without sacrificing centering / lock rock?
    I know you can bend the lockbar backwards to reduce tension... but every time I've done this, I've introduced some form of lock rock. No bueno. I know you can loosen the pivot, but this often sacrifices blade centering and often introduces horizontal blade play. No bueno. What else can I do here? I've heard of some people finding success "polishing" certain parts of the tang... either the bearing races or the detent track.

    Anything else?
    Last edited: Apr 3, 2020
  2. soc_monki

    soc_monki Basic Member Basic Member

    Apr 5, 2019
    What knives? If they're not riding on bearings, and you have a frame lock, it probably won't drop shut unless you loosen the pivot so much the blade wobbles.

    Don't decrease lockbar tension. As you see, you introduced lock rock and compromised your lock up.

    You don't need much lube. Very little in fact. The gritty action is most likely your detent ball riding on the blade. I use grease in the detent ball hole of the blade if I have one that won't smooth out over time. It helps.

    Dropping shut is not its cracked up to be anyway. Bearing knives will do it, but if a liner/frame lock washer knife does it it is kind of suspect in terms of safety.
    Wilfred17 likes this.
  3. Stwida


    Feb 12, 2020
    Currently goofing around with a ZT0452CF, CH Knives Emperor, and Bestech Bison.

    The ZT has always been dogshit, but I'm pretty sure I got a lemon, so we won't talk about that one.

    The CH Knives one drops shut, probably because the blade is so thick and heavy, but it sounds very gritty. This has not gotten better since breaking it in. I've literally just sat there swinging the blade back and forth for hours while watching TV and it continues to be "gritty".

    Bestech Bison is the same as the CH Emperor, but doesn't drop shut probably because the blade weighs 70% of the Emperor. VERY sandy sounding. It's not that it's not smooth - it's a good action... but very gritty. Tried the same thing as the Emperor - just sitting there working the pivot for hours. Still sandy. I cleaned it today and there was a ton of black gunk in the bearings. Not sure if wear from the tang, wear from the black DLC coating, or both. Probably both. Even with this wear, not any smoother.

    Am considering polishing the tang in the detent track.

    I know that drop-shut isn't inherently anything special, but given that I literally fidget with my knives more than I cut things with them, I'm quite interesting in understanding this.
  4. soc_monki

    soc_monki Basic Member Basic Member

    Apr 5, 2019
    Are the ch and bestec bearing knives? Sorry, not familiar with them!

    The zt probably does need work. All of mine are smooth and drop shut, except my 456cf, but it has more lockbar tension than any of my others. I don't mind, all it takes is a little encouragement and it closes.

    The ch and bestec are probably gritty because the detent track isn't worn in. Like I said, use a little grease (I use red lithium, but kpl heavy is supposed to be for that purpose, so you can try it). Put it in the detent hole of the blade. That way it refreshes every time it's closed.

    You can polish the detent track as well, I think spyderco does it, and it will help. I usually just let it happen naturally. I also don't polish washers or anything else either though. No need, because it will happen naturally.
  5. Stwida


    Feb 12, 2020
    Yeah, they're all on bearings.

    The KPL Heavy honestly doesn't seem to do much... Maybe I'm just being stubborn, but if it helps, it's only marginally.

    Might just goof around with polishing the detent track. Sounds like that's my issue. I'm just surprised that "naturally" takes so long - I'm not exagerrating when I say I've spent hours manually working the pivots on these knives.

    I will give the ZT one thing - It's not gritty at all. Never has been. Feels like polished glass riding on polished glass.
  6. soc_monki

    soc_monki Basic Member Basic Member

    Apr 5, 2019
    I don't know how ch and bestec finish their blades. I know spyderco is polished on the detent track, at least for usa knives. Zt I believe is pretty slick as well. Benchmade however doesn't, but they don't have to on axis lock knives. Just have to polish where the axis bar rides.

    So if the blade has grind marks where the detent ball rides, that's your issue. Hours may not accomplish what you want. If the grind is really rough, knock it down and action should improve.

    I use kpl myself. I don't know if it's the best, but it works well and I like the smell. Plus one bottle will probably last me years. Lol
  7. drail


    Feb 23, 2008
    To get rid of the grittiness you can either soak the knife in a mild solvent (naptha works well) and blow it out with high pressure compressed air (do this several times) or tear the knife completely down, wash in solvent and lube and reassemble. If any of the bearing surfaces are rough polish with 600 to 1000 grit sandpaper. My main lube these days for knives and guns and locks is Marvel air tool oil (available in any auto parts or hardware store). You only need a little and it won't evaporate away overnight. I have used just about every lube on the market and air tool oil is hard to beat. Dexron automatic transmission fluid is also very good and easy to find. Don't waste your money on any of the miracle lubes that are on the market - they don't perform any better and are way overpriced.

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