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Thread: Drill bits

  1. #1
    Join Date
    May 2008
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    Belle Plaine Iowa
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    270

    Default Drill bits

    Some time ago I bought a set of Dewalt pilot point drill bits. I have found that its not a good idea to drill a pilot hole for a larger bit as the tip of the bigger bit is easily broken off.

    Recently Ive had a couple of jobs to do that for some reason consumed several bits in the process. Job one, drilled holes for self tapping bolts in a flatbed trailer deck. First drilled large hole in aluminum(for bolt to pass thru) then drill smaller hole in steel I beam crossmember(for self tapping portion). Putting in about a dozen bolts, I managed to bend the larger bit and bend or break off three of the smaller ones. This was all done with a half inch B&D drill. These bits seem to "catch" badly just when the hole is almost complete.

    Today with a near new(19 holes) bit(same size as the small ones above, 17/64) I broke one off in aluminum. Im frustrated beyond belief as its about a 60 mile round trip to buy new bits.

    Did I end up with crappy tools with a good name on them or am I doing something wrong? What brand bits are you professionals using? Do you guys use them by the bucketfuls too???
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  2. #2
    Join Date
    Oct 2012
    Location
    Neosho Mo
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    70

    Default

    Those dewalt pilot point bits are trash. Same thing here. The dewalt bits without a pilot are a lot better.

  3. #3
    Join Date
    Sep 2005
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    northern NJ
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    Default

    I usually get my bits from McMaster-Carr. Just get the regular black oxide jobber bits. Any supply house should have them such as Fastenal, etc.

    http://www.mcmaster.com/#standard-drill-bits/=oufuag

    I always drill pilot holes for any job. You really need to brace yourself when using a hand drill to keep it straight when it grabs. Also it needs to be straight the whole time you are drilling. A lot of it is technique. I don't know how many times I see someone using one hand or going crooked while drilling.
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  4. #4
    Join Date
    Sep 2012
    Location
    Coastal Maine, Coastal NC
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    21

    Default

    Some suggestions:

    Stay away from imported, mass market drill bits. You know, the kind you buy at the Depot. Buy USA made drills from McMaster-Carr, ENCO, MSC etc.

    For your kind of work, I might suggest that you also stay away from the "split point" drills which can be very aggressive, particularly if you've drilled a pilot hole. Use the standard point drills.

    Also, consider using some sort of cutting fluid if possible, particularly for aluminum which can be quite "grabby" when drilled with hand-held equipment.

    Be aware that all drill bits become very aggressive as they break through the bottom of the drilled hole. You can usually feel this as it starts to happen and you need to ease off on the applied force.

  5. #5
    Join Date
    Apr 2010
    Posts
    264

    Default

    When drilling a pilot hole, don't make it any larger than the web thickness of the larger drill.
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  6. #6
    Join Date
    Jun 2009
    Location
    las vegas
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    Default

    Agreed. The bits you buy from the fastenal work great with cutting fluid. I use brake fluid. It washes with water. But thats me. The rapid tap oil works great
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  7. #7
    Join Date
    Dec 2011
    Posts
    388

    Default

    When you sharpen your bits for this type of work keep the rake to a minimum. It will cut slower but will grab less. Don't push your drill though let it cut its way though and as stated, ease up when your close to dropping though.---Meltedmetal

  8. #8
    Join Date
    Apr 2011
    Posts
    360

    Default

    This happens a lot when drilling bolts when safety wiring bolts. I have found that if you don't tighten the bit down so that it may slip at the point of break through you can save a few bits... That may not work as well for the bigger stuff.
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  9. #9
    Join Date
    May 2008
    Location
    Belle Plaine Iowa
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    270

    Default

    Thanks for all the replies. I do let up at the end of the hole, but with this particular job it didnt seem to matter. I will be investing in some other bits. Many thanks for the brand names. One thing I liked about these Dewalts is the shank is not round, very easy to keep tight in the chuck.
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    Old cutting torch on LPG

  10. #10
    Join Date
    Feb 2012
    Posts
    226

    Default

    I use Irwin high speed bits. There the cheapest but work the best for me in alum and steel. We get them at a old local lumber yard there silver colored. I've try all the high dollar ones not no more. They resharpen good too. One of the few cheap products that work.
    Last edited by Kpack; 10-10-2013 at 07:03 PM.

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