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Smallest possible hole through a 2" ball bearing? How?

Discussion in 'Steel' started by Bill Kahn, Jun 17, 2017.

  1. Bill Kahn

    Bill Kahn United States Iron Registered Member

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    I am making a variation on Newton's Cradle--you know, where the steel balls bounce against each other. But for my purpose the steel balls need to slide up a line (string/thread/cable). The coefficient of restitution is important in my application so I want to use very hard steel. Ball bearings probably. The largest will be 2" diameter.

    I need to drill a hole through a diameter of the ball bearing. I guess I could buy some expensive carbide drill, say 1/2" diameter and make it through the bearing. But I would much rather use a much thinner guide line. Ideally even I would like to use .01" fishing line. But .05" wire would be ok too.

    I have no idea how to drill a .01" hole through 2" of hard steel. I think that I start with a 01" .2" long carbide bit and then, with .2" supported go to a .4" long bit. Then a 1" and then a 2". Are such bits made? Would that sequence work?

    Or, is there a water jet technology? James Bond like lasers? Or some totally other way to get a tiny hole through 2" of hard steel.

    If I can't get a .01" hole, what can I get? How small can the 2" hole be? How?

    Thank you for any advice.

    -Bill
    45 years ago loved high school shop. And finally getting back to it.
     
  2. Ulma Doctor

    Ulma Doctor Infinitely Curious Active Member

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    EDM comes to mind
    i suppose carbide will be the next possibility
    otherwise i'm scratching my head.
     
  3. RJSakowski

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

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    Bill, you need to look for a harder project!

    Seriously, you have picked a formidable task. Drilling a .01" hole through 2" of steel would be hard enough but through a hardened ball bearing? Wow!

    A water jet may be able to do the task although it is a fairly deep hole. It might be possible with a laser as well. My gut feeling is that you wouldn't get a clean hole that deep. EDM would have to be done with carbon electrodes and a carbon rod .01" in diameter and 2" long would be rather flimsy.

    A thought would be to make a larger diameter hole and insert a bushing with the desired i.d. The hole could be drilled or EDM'd. Once a pilot hole was made, wire EDM or a laser could give you a clean hole.
     
  4. whitmore

    whitmore United States Active Member Active Member

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    EDM (i.e. judicious use of lightning) can drill hard material, as can grinding (ultrasound pecker and abrasive
    grit). Neither is very fast or suitable for deep/narrow holes. Could you create the ball from unhardened material,
    drill that, and re-harden it?
    Or, could you use a glass bead? Those are formed on a bit of wire, and (by stretching the wire)
    you get a nice hole, without all the distress of machining it. Restitution is good (glass rings like a bell).
     
  5. T Bredehoft

    T Bredehoft Active User H-M Supporter-Premium

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    .010 drills are really tiny. I routinely drill .036 holes through 3/16 aluminum, generally get about 6 good holes per drill. They break easily. And, finding good, well sharpened .036 drills is a challenge. I bought 20 once, found 6 that would cut aluminum. The others were improperly ground. .010 is really tiny. No. 80, the smallest commercially available is .0135.
     
  6. extropic

    extropic United States Active User Active Member

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    4gsr and Bill Gruby like this.
  7. Dabbler

    Dabbler H-M Supporter - Premium Content H-M Supporter-Premium

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    Bill I know two tool and die makers, and they verified my first impression. In a fully equipped manual tool and die shop there's no way a professional T&D would take the job. Your only hope is laser drilling (about 80$ per hole) or fast die sinking EDM (at about $100 per hole). These prices are from jobs I have personally had done in the past (not in ball bearings, however) Because the surface is not perpendicular, the waterjet shop I use wouldn't touch it either because the hole won't sink properly...
     
  8. whitmore

    whitmore United States Active Member Active Member

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    For an EDM drill, neither graphite nor copper are suitable (long, thin, floppy copper or
    high-electric-resistance graphite), but a less-durable tool can be fashioned from the small SS tubing
    such as hypodermics use. 22 gage (about 0.028" diameter) to 27 gage
    (about 0.016" diameter), with some kerosene flow through the central hole to cool and flush
    the cut, would make holes under 0.040". Slowly. With lots of tool wear (and replacing the
    cutting tube means some alignment fiddling).

    Spinal needles up to seven inches long are of such tubing.
     
  9. Silverbullet

    Silverbullet Active Member Active Member

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    Could you spot weld a link or ring to the balls ?
     
  10. Bill Kahn

    Bill Kahn United States Iron Registered Member

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    Wow. Thank you everyone. Now isn't this a case of out of the "mouths of babes..." I would have thought drilling a hole (albeit small) through a metal ball (albeit hard) would not have been well near impossible. But, so be it. While it may well be possible to have some professional make it for some price, I am enjoying making stuff myself. Like for all hobbyists, it is the journey. I have many other ideas of simple projects that have caught my eye. While help in getting going on a project is always wonderful, knowing I have bitten off too much is even more so. Thanks again. Best, -Bill
     
  11. kd4gij

    kd4gij United States Active User Active Member

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  12. pdentrem

    pdentrem Active User Active Member

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    We use a EDM made for tiny holes in hardened steel. Smallest is 0.006" but I believe 0.004" is possible. We usually make 0.012" to clear 0.006" wire. Full stroke of about 4" I believe. Most of the time we are using 1/2" to 1 1/2" steel. This is not our machine but similar. http://www.sodick.com/products/smallholeedm/k1c.htm They may not be common in your area but a quality shop should know who does. Surprising fast, it uses a brass hollow tube that the flushing coolant flows through as the tube spins and plunges down and through the steel.
    Pierre
     
  13. Dabbler

    Dabbler H-M Supporter - Premium Content H-M Supporter-Premium

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    Pdentrem, that's one i've never heard of! Thanks for sharing!
     
  14. Bill Kahn

    Bill Kahn United States Iron Registered Member

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    From http://www.ebay.com/bhp/sodick-wire-edm looks like they range in price from like $6K to $60K used on eBay. This is more than a small step up from my hobby mill, but also looks like a blast. -Bill
     
  15. RJSakowski

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

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    Bill, a wire EDM uses a moving wire as the electrode. The wire is threaded past the surface to be machined, which in your case would be a through hole, and the wire is a consumable. since you don't have a pilot hole, it wouldn't work for you.

    You would need something like their K1C small hole EDM. You can pick one up on eBay for $20K.
     
  16. brino

    brino Active User H-M Supporter-Premium

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    Last edited: Jun 19, 2017
    4gsr likes this.
  17. Bill Kahn

    Bill Kahn United States Iron Registered Member

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    Well, I tried several carbide bits. The ones from Home Depot--carbide tipped, would literally not even scratch the ball. (I have flatted the 1" ball a bit with a small grinder, so I am trying to learn to drill on a flat surface). And I bought a 10$ 1/8" carbide bit from JTS. Well bolted down. Cutting oils. Light pressure, different speeds, nothing. Medium pressure, different speeds, nothing. Slightly more pressure--yeah, what you would expect-snap. Carbide shards clear across the shop. Most glad I had safety glasses and a face shield--bits sure can fly when they shatter. So, I am in agreement now with the wisdom/experience of this thread. Drilling a ball bearing is not something for a simple garage hobbiest. But, as it is the journey, I'll call it a qualified success. Even if my ball bearing still isn't even scratched. -Bill
     
  18. markba633csi

    markba633csi United States Active Member Active Member

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    Most of the "Newton's cradle" I have seen just attach the strings to the balls with a small bump of epoxy. Waxed strings so they can be adjusted later (string pulls thru the epoxy)
    Mark
     
  19. Bill Kahn

    Bill Kahn United States Iron Registered Member

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    I am aiming more for something like
     
  20. Bill Kahn

    Bill Kahn United States Iron Registered Member

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    Whoops, didn't finish that post. It is bouncing steel, thus my reference to the cradle. But actually it is a triple (or quadruple) ball bounce on a 20 foot (or more?) rod (or very taught (turnbuckle taught from a ceiling beam) line/wire) with an anvil-like chunk of mass on the bottom. Normal steel balls (not hardened) will probably work too, but I was hoping to get the best possible coefficient of restitution. I have given up on drilling ball bearings.
     
  21. pdentrem

    pdentrem Active User Active Member

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    Cool, I have seen it done with super balls and golf balls before.
    Pierre
     
  22. DaveD

    DaveD United States Active User Active Member

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    How about one of those cheap dremel, diamond dust coated, grinding points? I'm pretty sure my 8$ set has the equivalent of a ⅛" burr in it
    Run at slow speed and keep the coolant on it.
    Aren't thos balls just surface hardened? If so once you get past the hardened surface you might be able to continue with a regular drill till you hit the opposite hardened side.

    You might try a you tube search for something like drilling ball bearings and see what pops up.
     
  23. whitmore

    whitmore United States Active Member Active Member

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    Oh, a lecture demo! I used to assist on those... The alignment for a three-ball bounce can also
    be arranged without a central hole, by putting the three onto swinging arms (and a loose
    friction fit can allow the smallest ball to escape its collar). You want three arms
    (meter-long wood sticks?), three pivots (a stand with some pivots, or ball bearings if
    you want to be fancy), and affix the sticks with collars around the balls, so they
    hold the balls but don't damp the movement.
     
  24. easymike29

    easymike29 United States Active User Active Member

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    Try to find a local shop that has a "hole popper"

    Gene
     

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