drill optimize in eagle

Thread Starter

strantor

Joined Oct 3, 2010
5,971
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?
 

Pencil

Joined Dec 8, 2009
272
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
 

Thread Starter

strantor

Joined Oct 3, 2010
5,971
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.
 

Pencil

Joined Dec 8, 2009
272
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.
 

nerdegutta

Joined Dec 15, 2009
2,684
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.
 

osx-addict

Joined Feb 9, 2012
122
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.
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:
 

MrChips

Joined Oct 2, 2009
26,478
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.
 

Thread Starter

strantor

Joined Oct 3, 2010
5,971
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.
 

BSomer

Joined Dec 28, 2011
434
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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