drill optimize in eagle

Discussion in 'General Electronics Chat' started by strantor, Jul 3, 2012.

  1. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    I remember coming across some info a while back about a function of eagle cad that would oversize all your pads so that your drill bit would center properly on them. I can't seem to find it in eagle nor can I find any info online.

    Any clue what I'm talking about and how to do it?
     
  2. Pencil

    Active Member

    Dec 8, 2009
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    Design Rule Check (DRC)--->Restring tab

    Change % and Max values for layer you need.

    Apply.
     
  3. Pencil

    Active Member

    Dec 8, 2009
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    Or maybe you wanted:

    Select window (dotted rectangle icon on left)
    Left click, hold, drag to select.
    Change (wrench icon)--->Drill--->Checkmark size wanted
    Right click in drawing window--->Change Group
     
  4. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    Ok, I tried the DRC> restring thing you recommended and I was able to sort of accomplish what I wanted, but the unwanted side effect was that, in addition to making the inside hole of the pads smaller, it also made the outer diameter of the pad larger. Some of my pads were almost touching.

    I found the thing I was referring to before, you go file>run and click drill-aid.ulp. it draws another circle inside the pad and leaves the outside unaffected.
     
  5. Pencil

    Active Member

    Dec 8, 2009
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    One thing I found to help drilling holes by hand
    is to take a good centerpunch, or some kind of
    sharp pick and very carefully "dent" the middle
    of the pad before drilling. Under a good strong
    light and in a comfortable position works the best
    for accuracy. The resulting impression will guide
    the drill quite well. I use this technique for
    hand drilling before etching. My choice of drill size
    is #66 (.033"), and a small lightweight cordless
    drill.
     
  6. nerdegutta

    Moderator

    Dec 15, 2009
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    I'm using Eagle, and I set the minimum drill bit to be 0.6mm. The center of all pads are etched, and my 0.7mm drill bit aligns perfect inside the pad. I also have a small piece of tape, on the drill bit, to act as a fan and blow away the dust from the pcb.
     
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  7. osx-addict

    Member

    Feb 9, 2012
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    I would also think that IF you had a drill press handy that might work as well as long as you could clamp down the board to ensure it doesn't get away from you and get flung across the room! :eek:
     
  8. MrChips

    Moderator

    Oct 2, 2009
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    Not at 33t holes.
    I hold the board by hand and use a Unimat setup as drill press. I set up the belt for highest speed possible.
    I use carbide drills. Make sure there are no lateral forces otherwise you'll snap the drill.
    No need to prepunch the holes. The drill centers on the pad holes easily.
     
  9. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    I googled unimat and all I see is lathes. Is that what you're using? I can't picture how to drill PCBs on a lathe.

    I'm using a drill press, with #33 carbide bit, without issue. When I tried last year I was using a cordless hand drill with HSS bit and getting unacceptable results. Drill press is much better, but slow.
     
  10. MrChips

    Moderator

    Oct 2, 2009
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    The Unimat is a miniature lathe/mill/drill system.
    The head can be removed and positioned vertically to make a miniature drill press:

    [​IMG]
     
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  11. BSomer

    Member

    Dec 28, 2011
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    I use the drill press attachment thingy for my dremel tool. I also put some white LEDs under the base to shine up through the hole in the center. The light shines through the PCB and helps line things up.
     
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