slip joint question...possible galling

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by jwesthurl, Jul 19, 2018.

  1. jwesthurl

    jwesthurl

    428
    Sep 17, 2013
    So I've been working on a slip joint on and off for a while and I assemble the heat treated blade and spring to the liners and tested the action. First few opening and closings were fine but now it seems that the tang is galling the spring. I thought it was well polished and I didn't use any type of lube. Does this mean that my spring is too soft? Do I need to re-heat treat the spring?
     
  2. SBuzek

    SBuzek KnifeMaker Knifemaker / Craftsman / Service Provider

    Dec 7, 2006
    no, you have a bur on your tang. They can be very small but will eat a spring.
     
  3. HSC ///

    HSC /// KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Nov 7, 2012
    galling, so the spring is showing evidence of wear?
    why aren't you using any lube?
    do you know what the spring hardness measures in at?
     
  4. Bill DeShivs

    Bill DeShivs KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jun 6, 2000
    Stick a little lithium automotive grease on it and wear it in.
     
  5. javand

    javand

    Oct 17, 2010
    Yeah, a burr can definitely be an issue, but how are you sure it's galling? Can you see it? Or is the action just sticking or have friction suddenly and it's not wanting to fly between positions on it's own? You will typically have some material being "abraded" off the liners and potentially the spring after you pin it together, in what we refer to as the "break-in".. Typically accomplished slipjoint makers will take this into consideration when they're setting up their action.

    If this is the case, you need to get some oil or grease down in the action, open and close it a bunch of times, then flush it heavily with a solvent, and lots of compressed air, blowing out any stained lube, cleaning it completely, then re-oiling it with a good oil for this use, like Quick Release or Nano oil. Typically you'll see a big improvement.

    If it is galling heavily, you may have to take it apart. Deburring everything is critical in constructing these knives, but it's a lesson each of us learns from having a problem typically. I think all of us have had to take one apart because everything was flush and perfect, until we opened the knife 20 times, and suddenly the spring is landing below the liners, because we dialed it in, riding on top of a bur somewhere. It's amazing how much they can screw things up.

    Another thing to ask yourself; is it necessary, or even advantageous to polish all mating surfaces in the action? Highly polished surfaces under pressure and friction, are more prone to galling, especially the softer of the two.

    The slickest actions I've ever felt, weren't even highly finished on the tang and spring. There's a lot of personal preference and theory here, but don't assume that polishing is what's necessary to accomplish this. I'm not saying it doesn't have a place, but be careful, especially on the engagement area of the spring, where the tang rides.
     
  6. Drew Riley

    Drew Riley AR Custom Knives Knifemaker / Craftsman / Service Provider

    Oct 17, 2007
    Pictures may be helpful. I assume you've radiused the corners of your tang?
     
  7. Randy3000

    Randy3000

    802
    Jun 3, 2017
    It is good to barely radius tang corners but dont try to radius tang edges. Did you grind the decarb off the spring after heat treating?
     
  8. jwesthurl

    jwesthurl

    428
    Sep 17, 2013
    Thanks, I will check that carefully

    From what I can tell. I said galling because it looks like some steel was scraped off the spring and stuck to the tang. No lube because I was just testing the action with the liners. I do not know the hardness.

    [/QUOTE]
    I misspoke here. By “well polished” I meant an even 600 grit finish
     
    Last edited: Jul 19, 2018
  9. jwesthurl

    jwesthurl

    428
    Sep 17, 2013
    Yes the corners are radiused. I’ll try to get pics
     
  10. javand

    javand

    Oct 17, 2010
    I misspoke here. By “well polished” I meant an even 600 grit finish[/QUOTE]


    Gotcha, well I wouldn't expect any significant galling under those circumstances, unless, as Stan mentioned, you've got a bur. You will see a "track pattern" in the spring where the tang cams ride it as it's breaking in, sometimes it looks a little "gall"-ish, but unless it feels sticky/chunky in certain parts (not consistent friction, through the cam engagement, which is another issue, i.e. binding or needing cleaning or more break-in), it's not a galling issue.

    A spring can be pretty damn soft, and still work fine, I don't recommend it, but many springs and tangs were soft on knives from 100+ years ago.
     
    Ken H> and SBuzek like this.
  11. JDWARE

    JDWARE

    224
    Nov 28, 2011
    All good advice here and things to look at. Another possible cause can be too great of a difference of hardness between the spring and the blade. You haven't mentioned what steel you're using or the Rc hardness of the spring and blade. I think with anything other than simple carbon steels, you really need to know the Rc's.

    You can only harden the spring so much before it's too brittle, so I've taken to softening the tangs of the blades. Just after hardening and tempering, I clamp the blades between two aluminium quench plates, and heat the tang with a torch. Quench; polish off the color; repeat. The quench plates prevent heat from traveling up the blade and ruining the temper. I do this for carbon and stainless. I'm not sure how deep the effect is with such a short "soak time" on the stainless, but it works.

    Saludos
    J
    JDWARE KNIVES

    [​IMG]
     
    Alan Davis Knives likes this.
  12. HSC ///

    HSC /// KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Nov 7, 2012
    interesting about that finish on the end of the spring and tang junction,
    I'm looking at three knives I own from Horn, Dunn and Wilburn, and none of them are close to that 600 finish.
    Javan already mentioned about whether it's necessary or advantageous, but there's certainly nothing wrong with your choice of a higher level finish.
    Mine are at 220 belt finish.
     
  13. JDWARE

    JDWARE

    224
    Nov 28, 2011
    re. softening the tang....... I think an added benefit is more even wear between the spring and the blade.
    J
     
    Last edited: Jul 19, 2018
    Alan Davis Knives likes this.
  14. kc custom

    kc custom KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Apr 20, 2005
    I used to battle with this years back. At this point its probably best to take the blade out and clean
    the blade tang and spring. Also with the knife in 1/2 stop position, and the trough facing up, squirt
    an eyedropper of acetone right in the joint and blow it out good with an air compressor. Then before
    any working or much movement get a light grease in the joint----- then work the knife. Good luck.
    Ken.
     
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  15. jwesthurl

    jwesthurl

    428
    Sep 17, 2013
    it's 52100 and I have no way to test the hardness

    Thanks Ken. It's not assembled yet so I'm going to make sure to clean up the tang and spring really well and make sure there are no burrs.
     
  16. John L

    John L

    Oct 28, 2004
    I have a small tube of graphite like used by locksmiths, a drop of oil and never any galling. I put both on contact points and work the blade 20 cycles or so. Then clean out and one small drop oil. Galling then is not a problem
     
    Don Hanson III likes this.
  17. Don Hanson III

    Don Hanson III KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Oct 3, 2002
    Lube is the answer, especially the first time spring and blade make contact.
     
    Ken H> likes this.
  18. jwesthurl

    jwesthurl

    428
    Sep 17, 2013
    Thanks John, if I ever finish this thing, I’ll drop by and have you critique it!

    Thanks Don, I’ll remember for the future!
     
  19. mete

    mete

    Jun 10, 2003
    To correct any misunderstanding ..Galling is cold welding . Major considerations are hardness types of metal, finish and lubrication.
     
    kuraki and Don Hanson III like this.
  20. jwesthurl

    jwesthurl

    428
    Sep 17, 2013
    Yes, thanks for the clarification Mete. I thought that’s what I had happening. I had some steel stuck to my tang that I believe came from the spring. I was able to pop it off with my fingernail so maybe a burr pulled some material off the spring after opening and closing a few times? I’m going to clean the mating surfaces really well and lubricate before trying again
     

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