Drilling Freewheel Hub For Larger Bolts

Discussion in 'Motorized Bicycle General Discussion' started by 5-7HEAVEN, Feb 19, 2012.

  1. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    I have SBP's HD White Industries freewheel one on my 72t engine sprocket/shift kit. I removed the crank arm with attached freewheel for SBP's suggested maintenance. It's been a few hundred miles on the road. The wheel's five holes are small, so accept small bolts. My bolts are bending slightly. I want to drill these to accept Grade 8 1/4 x 28 bolts. I tried a reamer, files, even cobalt drill bits, but they don't even scratch let alone cut thru the tough steel. The machine shop will drill the holes oversize for $80.....or more.

    I'd rather DIY.

    I have a HD Milwaukee 1/2" drill (not cordless), but it's not doing the job.

    What do I need? :-||
     
  2. H.R. huffinstuff

    H.R. huffinstuff New Member

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    tough ass drill bits, oil, patience and a strong wrist
     
  3. bandito

    bandito New Member

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    Get a HF drill bit sharpener and have patience. Oil and slight pressure is all thats needed as long as the bit is cutting material. Fast isn't the best either if you can regulate the drill speed.
     
  4. Ibedayank

    Ibedayank New Member

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    case hardened steel just won't drill. you can grind it but will take a long time
     
  5. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    I dunno, man. After an hour of drilling, not even a scratch.:-||

    The small hole is EXACTLY the same size as when I started.
     
  6. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    So what would you suggest?
     
  7. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    It can be done........and as others have suggested. The main thing is low speed. May take a handfull of drill bits or sharpening bits several times and a good cutting oil. Go slow and be patient.......or pay $80.

    dnut
     
  8. The_Aleman

    The_Aleman New Member

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    Access to a drill press and a wide size range of new drill bits will do it. Baby steps :D
     
  9. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    Thanks guys. I'll buy more bits and keep trying for now.
     
  10. dtj6ppc

    dtj6ppc New Member

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    Anneal soften the holes by heating, the hole areas only, to a cherry red and let air cool to room temp., drill using slow rpms and fast feed rate to create long cutting metal slivers that will prevent work hardening.

    Not sure about this, but your problem maybe that you are trying to drill thru quality chromed surface which can be difficult until the chrome layer is penetrated and you get to the softer underlying steel base material.........Don
     

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