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Dum question: best way to drill sheetmetal?

Discussion in 'The Hokey Ass Message Board' started by Johnny1290, Nov 26, 2007.

  1. Nicholson
    Joined: Aug 9, 2006
    Posts: 169

    Nicholson

    Another vote for the Rota-Broach cutters made by Blair. I use them everyday in my shop. I was skeptical at first but they cut real smooth without grabbing. I use a 3/32 pilot hole or a center punch. If you use a center punch start out slow until it cuts a ring then you can apply more pressure. If you don't it will walk all over the place. Here's the link http://www.blairequipment.com/
     
  2. duwty
    Joined: May 10, 2007
    Posts: 64

    duwty
    Member

    i didnt know they made anything but step bits for sheet metal-----
    no really i use a step bit all the time at work
    we have one thats really good but it was 40 or 50 bucks
    but ive also used some cheapo irwin step bits with great success
    you can push hard and go fast with the step bits, youd have to really get them in a bind to break em
     
  3. Unkl Ian
    Joined: Mar 29, 2001
    Posts: 13,509

    Unkl Ian

    I sharpen my twist drills to a Brad Point,for use on thin sheet metal.

    Leaves very little burr,if any,and I can drill a round hole any size
    in 20 gauge with only a center punch mark to start with.
     
  4. Johnny1290
    Joined: Apr 20, 2006
    Posts: 2,834

    Johnny1290
    Member

    sweet jimminy reverse?!? Could it be?!? I'm goin by the shop now to see what size bottle on the mig. I'll check the drill and report back. Regardless I knew there had to be a better way than what I was doin. Now I have a lot to think about. I couldn't get thus kind of experienced help anywhere else. Thanks you guys.
     
  5. sawzall
    Joined: Jul 15, 2002
    Posts: 4,757

    sawzall
    Member

    this isn't a dumb question.. most of the guys I have worked with do one of two things incorrectly.. Drilling or Grinding..

    in my job as I spend some time instructing students on how to drill based on material type, thickness, cutter diameter, etc etc..

    and I must admit.. I get a kick out of the students who accidentally have the drill in reverse. I often wait till they are fully frustrated to intervene. (ensuring that wa that they only make the mistake once)

    the centering drills you found on ebay are what you want to start with.. every time.. in any drill..
    I like the ones that are .25 dia at the largest.. because I usually need to drill that dia hole for my step drill. (or hole saw)

    I never buy expensive drills.. just cheap ones (I have a sharpener)

    the trick i have found (from working with stainless) is this:

    (hand drill only)

    using ANY drill bit

    While applying firm pressure to the drill, I "trigger" the drill so that the drill rotates quickly and comes almost to a stop, then quickly repeat the process.

    if you do this right your trigger finger will get a workout and your drill will sound like your "revving" it up.

    this (i have found) keeps the drill bit cooler, and cuts the hole faster.
     
  6. Irrational Metalworks
    Joined: Feb 5, 2007
    Posts: 589

    Irrational Metalworks
    Alliance Vendor
    from DFW

    Some good advice in this thread and a bunch of bad!
    If you want true, round holes in sheet metal, there are really only two ways that I have come across. One is a step drill, and the other is a rota broach. I prefer a rota broach mainly because it cuts faster. With either one, a pilot hole needs to be used.
    My 2 cents, for what its worth!

    Tim @ www.irrationalmetalworks.com
     
  7. Zombie Hot Rod
    Joined: Oct 22, 2006
    Posts: 2,452

    Zombie Hot Rod
    Member
    from New York

    Get a good set of colbolt bits, they will last you a long time before they get dull. I alway start with a regular bit, then go to the step bit to enlarge the hole...
     
  8. jalopy43
    Joined: Jan 12, 2002
    Posts: 3,085

    jalopy43
    Member Emeritus

    At the GM plant , we used' fish tail' drills, kinda of an inverted v, with a small centering point...??anyone??
     
  9. roddinron
    Joined: May 24, 2006
    Posts: 2,676

    roddinron
    Member

    another vote for HF step drills, I was ordering some stuff and just added them to my order since they were on sale so cheap, I was surprised how good they work.
     
  10. roddinron
    Joined: May 24, 2006
    Posts: 2,676

    roddinron
    Member

    It's worth 2 cents ain't it?;)
     
  11. jalopy43
    Joined: Jan 12, 2002
    Posts: 3,085

    jalopy43
    Member Emeritus

  12. Unkl Ian
    Joined: Mar 29, 2001
    Posts: 13,509

    Unkl Ian

    Never heard that name,but it sounds like the Brad Point drills I use.

    [​IMG]

    I just resharpens regular twist drills into brad points when I need them.
     

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