mlerman wrote this instructable detailing the build of his USB microscope guided PCB drill:
Most of the printed circuit boards I make at home are simple single sided boards. Drilling requirements are minimal, mostly holes to mount the board and an occasional through-hole component or connector that is only soldered on one side. For these boards I generally use a small, high speed drill press with carbide drills, eyeballing the location and hoping it is “good enough”. Unfortunately, often it is NOT good enough, and a lot of the holes have to be enlarged or elongated to fit. Now that I am attempting double sided PCBs using my modified E260 laser printer to print toner directly on the copperclad board (see E260 Instructable), I realized that my hole drilling has to be a lot more accurate. So I decided to build a USB Microscope Guided PCB Drill.
Indentations as drill bit guides are better, no squirming around ever. Also much cheaper (or free) and nothing to maintain. Just use an old divider from your math instrument set. Hold firmly and make a indentation on each hole to be drilled. Done hundreds of them holes that way.
Of course, doing this for a >100 hole PCB can tax the wrist muscles, but look at it this way, it’s good exercise for your claw hand kung fu. :-)
Easier still is to etch away a small void in the copper at the center of your holes. On 1 oz copper there is enough of a relief to allow the drill bit to self-center.
You *do* need to develop a technique where you allow the board a slight bit of movement to center on the drill bit and then hold it firmly while drilling the hole home. You are going to break a few carbide bits while learning so don’t sweat that. But once you get the hang of it drilling goes right quick.
BTW, I tried using the microscope trick but I found the latency to really slow things down. If you can eliminate (or at least dramatically reduce) the latency this technique would be much more viable. IMO, at least.
Yeah, in my case I use KiCAD and leave small holes in the pads for the PCBs I make. Indentation just makes it easier to center the drill bit versus the small voids you mention. I agree that once you can ‘feel’ the centering, one can drill at a steady pace.
One more thing to suggest: I use enlarged pads for practically all through-hole pads, using a custom library following the style of KiCAD’s ELL-style DIP footprints. So even a slight misalignment rarely becomes a problem.
Add to the previous tips a good illumination. I have to 100mA leds mounted on flexos, so I can position them near the tip. The two aditional shadows also helps.