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Help with counterbores

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Stang Bladeworks, Oct 12, 2019.

  1. Stang Bladeworks

    Stang Bladeworks KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    500
    Feb 19, 2018
    Hi,

    I am having some issues with my counterbores. I am using a 3/16 pivot and i need to use a counterbore to get a .500" pocket for my bearings.

    I am using a carbide tipped c/b from ti connector. I am drilling my holes to .185 and reaming to .1875. My pivot barrels seem to fit properly in my reamed holes.

    When I go to use the counterbore it seems like the removable pilot is expanding and getting caught in the hole. I snapped one earlier today in the pivot hole.

    I ordered another from mcmastercarr to see if i had better luck. Theirs is flawed in design and wont ever work. Ill post pics below.

    I have a 3/8 c/b also from ti connector and it cuts much better. I am wondering if maybe there is an issue with the .500 one either from factory or from myself. It requires way more pressure than the 3/8 one and wont cut hardened steel at all. Im not sure if this is normal.

    I am running at 330rpm in my mill under constant coolant from a mister. I am wondering if anyone has any ideas or suggestions. Im a bit stuck. I will likely buy another from ti connector and see how it goes. These are getting expensive.

    I dont really want to oversize my holes. I dont want any lash if avoidable. What size are guys running there holes for pivots? Any ideas on why the pilot is getting stuck. It moves in the hole fine prior to starting and seems to swell while spinning inside.

    Thanks for reading.
     
  2. Stang Bladeworks

    Stang Bladeworks KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    500
    Feb 19, 2018
    Here is the one from mcmaster
    Hopefully i can save someone from making the same mistake as me...
    20191012_192439.jpg 20191012_192447.jpg
     
  3. razor-edge-knives

    razor-edge-knives Moderator Moderator Knifemaker / Craftsman / Service Provider

    Apr 3, 2011
    That's really strange. I use the hss ones with removable pilots from McMaster all the time with no issues in ti and g10/micarta.

    But if I had the issue you did I'd just turn the pilot down a hair, 400 grit belt with a hand drill should be perfect.
     
    Stang Bladeworks likes this.
  4. tkroenlein

    tkroenlein Gold Member Gold Member

    58
    Dec 10, 2016
    I think you have the wrong pilot/counterbore arrangement. Every counterbore I've ever encountered had the pilot overlapping the face of the cutter. McMaster Carr May not offer the correct arrangement for your needs. They tend to catalogue stuff that follows the "standard" for industrial hardware. If you call them, they will special order stuff though, if that manufacturer provides it. Might be worth a shot. I hope that makes sense.
     
    Nick Dunham and Stang Bladeworks like this.
  5. Jesse Latham

    Jesse Latham

    611
    Jul 4, 2010
    The pilots were tight on my counterbores also. I sanded the pilots down a bit until there is no sticking.
     
    Stang Bladeworks likes this.
  6. Ken H>

    Ken H>

    Dec 31, 2011
    Should that ridge right around the hole be there? I can see where it came from due to counterbore, but that doesn't look right to me. The carbide counterbore I have the cutter comes right against the pilot so there's no ridge left. I don't buy them anymore, just make my own from HSS W2 rod.
     
    Stang Bladeworks likes this.
  7. Stang Bladeworks

    Stang Bladeworks KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    500
    Feb 19, 2018
    It shouldnt be there its just a compatability issue. It should give a minimum pilot diameter on the website. All I could find was that it took a .1875 shank. It failed to mention that it would never work unless the pilot head was larger.
     
    Last edited: Oct 13, 2019
  8. Stang Bladeworks

    Stang Bladeworks KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    500
    Feb 19, 2018
    Out of curiosity does anyone have a good method of milling pockets in hardened steel? I leave .010 to remove after heat treat in case of any slight irregularity. When i tried to use my counterbore it wouldnt cut it at all and Im pretty sure that finished it off. I am nervous to try again because they are $100 each and the shipping sets me back 2 weeks. I thought about using an endmill since the pocket is already established but the bottoms are not flat. I could just mill the entire pocket in the ti but I kind of like having pockets in the blade. Any info is greatly appreciated.
     
    razor-edge-knives likes this.
  9. razor-edge-knives

    razor-edge-knives Moderator Moderator Knifemaker / Craftsman / Service Provider

    Apr 3, 2011
    If you need someone to sharpen it hit me up , I use a local company here they do a good job with carbide and hss
     
    Stang Bladeworks likes this.
  10. Stang Bladeworks

    Stang Bladeworks KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    500
    Feb 19, 2018
    Thanks man. Is it usually cost effective to get them sharpened? If so I will try to find a local place as well. If not ill give your guy a call.
     
  11. razor-edge-knives

    razor-edge-knives Moderator Moderator Knifemaker / Craftsman / Service Provider

    Apr 3, 2011
    Yeah definitely for the larger ones for sure
     

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