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Drill a 100% Centre in a Ball Bearing

Discussion in 'QUESTIONS & ANSWERS (Get Help Fast Here!)' started by faavs730222, Aug 29, 2017.

  1. grzdomagala

    grzdomagala Austria Iron Registered Member

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    Just an idea - drill oversized hole, fill hole with epoxy and "dip" the needle while holding it in spindle?
     
  2. RJSakowski

    RJSakowski H-M Supporter - Premium Content H-M Supporter-Premium

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    The wiggler ball doesn't need to be drilled dead center to work. The principle of operation is that the ball is connected by a short arm to another ball, a cylinder, or a point and is free to move to a position where the far end ball, cylinder, or point is aligned with the spindle axis. The design is such that it will compensate for any runout in the chuck or end mill holder. As long as the arm is close enough to the center line of the ball so any imbalance would throw it out, it will work. For that matter, the arm could be bent at the point of entry so the axis of the arm is passing through the enter of the ball.
     
  3. Ken from ontario

    Ken from ontario Canada Active Member Active Member

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    This is how Stefan Gotteswinter drills a small hole in a ball bearing, couldn't believe how easy he made it look (fast forward to 15:30 :
     
    faavs730222 and Bob Korves like this.
  4. ezduzit

    ezduzit United States Active User Active Member

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    What angle spotting drills are most useful? I see they are available in 82*, 90* and 120*.
     
  5. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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  6. DAT510

    DAT510 United States H-M Supporter - Premium Content H-M Supporter-Premium

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    I was taught you want the spoting drill to have a wider angle than you twist drill. 120 degree Spotting Drill for 118 degree twist drills.
     
  7. ezduzit

    ezduzit United States Active User Active Member

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    Thanks fellas. For some reason I never got notification of your replies--only found them by searching my subscribed threads, just now. In the interim my net search included an old PM thread http://www.practicalmachinist.com/vb/general/spotting-drill-bit-159845/ which led me to purchase a set of 120* French made cobalt spotting drills, from 5/32"-1/2" for $58, delivered. I know there's more than one way to do this, but these should increase my capability for a small investment.

    At 73 I'm still learning.
     
  8. Cadillac STS

    Cadillac STS United States Active User H-M Supporter-Premium

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    I ran across this homemade tool to hold a ball center for the lathe or mill. In the lathe and using the tail stock to drill it will be center.

    This is a bit big for your application but could be made smaller. Just chuck up some stock and drill the hole a bit smaller than your ball and part it apart or put two pieces of stock trued up together at the same time in the lathe so you don't have to part it.

    Could use hex stock to more easily mount in the mill.

    http://www.homemadetools.net/forum/sphere-drilling-jig-51534#post74617
     
  9. Dinosaur Engineer

    Dinosaur Engineer United Kingdom Active Member Active Member

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    Easy to make collet - drill & bore hole in some stock in 3 Jaw about 3/4 quarters the ball dia deep . Then put ball in and fully tighten the chuck. If you grind a small flat on the ball it helps.
     

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