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Thread: Drilling Boltheads - How Difficult

  1. #1
    AN bolts - undrilled are lets say $0.80, pre-drilled $4.00 each.

    How much work is that $3.20 saving going to be, drilling the 0.046 and 0.070 holes in the heads of AN bolts, from those who've done it?

    My thoughts are pay the extra, but if it isn't too bad to do I'll chain some electronic engineers or smaller siblings to a drill stand for a day.
    --
    Marko

  2. #2
    AN bolts - undrilled are lets say $0.80, pre-drilled $4.00 each.

    How much work is that $3.20 saving going to be, drilling the 0.046 and 0.070 holes in the heads of AN bolts, from those who've done it?

    My thoughts are pay the extra, but if it isn't too bad to do I'll chain some electronic engineers or smaller siblings to a drill stand for a day.
    --
    Marko

  3. #3
    Pay the extra, I made the mistake before to try to drill them afterwards to save some money. Those things are so hard and the drill bits so small....save your blood pressure and get them pre-drilled.

    In the end you're probably not saving any money by drilling them yourselves anyway- that would be an assumption you are more efficient at drilling bolt heads than the bolt manufacturer, which is unlikely.
    --------------------------
    Matt Giaraffa
    Missouri S&T (UMR) FSAE 2001 - 2005

  4. #4
    How many do you have to drill? That should be your question....

    They aren't that hard to drill if you have the proper drills and a good machine that will turn slow enough...just use lots of coolant/lubricant.
    B.J. Stoney
    Bearcat Motorsports Alumni '02-'07
    University of Cincinnati
    benjamin.stoney@gmail.com

  5. #5
    I wouldn't spend an extra 3.20 for the drilled heads.

    It's a matter of using a hard drill bit (cobalt, titanium coated, or carbide), holding the bolt head solidly in a vise, and using a slow speed and little pressure. I believe I did all 20 drilled head bolts on our car with 2 drill bits, in less than an hour. You should also chamfer the edges of the drilled hole.

    Matt Gignac
    McGill Racing Team

  6. #6
    I wouldn't spend the $3.20 a piece either. I've been cranking through them lately. The drill bits I've been using are only $1.60 a piece and they've been lasting quite awhile. Like Matt said just make sure you're not going to fast, you've got a good drill bit, and the bolt's solidly in a vise.

  7. #7
    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> I wouldn't spend the $3.20 a piece either. I've been cranking through them lately. The drill bits I've been using are only $1.60 a piece and they've been lasting quite awhile. Like Matt said just make sure you're not going to fast, you've got a good drill bit, and the bolt's solidly in a vise.

    </div></BLOCKQUOTE>

    +1
    "I couldn't find the sportscar of my dreams, so I built it myself" -Ferdinand Porsche

  8. #8
    The difference in price isnt that great. look at www.aircraftspruce.com

    I would spend the extra cash for the drilled heads. Thats time you could spend designing or sleeping.

  9. #9
    We saftey wire everything on our gearboxes.
    The key to make your life easier is a drill fixture.You can get it at Pegasus..worth every penny.

    http://www.pegasusautoracing.com/pro...asp?RecId=1192
    Scotty
    Taylor Race Engineering

  10. #10
    When y'all are saying go slow, I'm afraid you may be misleading...

    Turn the drill real fast, but feed it very gently and slow. Use cutting oil, don't be shy with it. Pull the drill out of the hole to pull chips out often. "Choke up" on the drill as much as you can, but still have enough length showing to reach all the way through the bolt.
    Kettering University FSAE Alumni

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