Homebrew PCBs

Leon Heller wrote:
> Having seen an old manual Excellon PCB drilling machine in action recently,
> I got to thinking about an up-to-date version suitable for home
> construction.
> 
> The nice thing about the Excellon was the large screen showing the magnified
> pad with cross- hairs, so that the drill could be exactly centred on the
> pad. One way to achieve this might be to use a webcam with a suitable lens
> attached underneath the PCB, with some software to create the cross-hairs.
> Alignment of the system could be achieved by lowering the drill with a bit
> in it, so that it was in focus, and moving the webcam/lens in the X and Y
> planes until the tip of the drill was centred. Centering a pad, then
> operating the drill, should result in the hole being exactly in the pad
> centre.

 From what Tom was once explaining about the manual Excellon PCB 
drilling machines he suggested the video camera is the way to go 
for this. I priced some of those cheapy B&W CCD camera modules 
and they retail for about AUD$60. They connect directly to any 
old TV/monitor with a composite video input. I can't see any 
optical cross hair eyepiece system being any cheaper or easier 
that a video display.

How were the cross hairs made visible ? Was it just some lines 
drawn on the glass of the monitor ?
Alignment should be easy. Just drill a hole , and while keeping 
the PCB in the same position you adjust the camera angle so the 
hole aligns up with the cross hairs ?

This is something what I might be able to add to my drill press.
http://home.alphalink.com.au/~seychell/drill_MkII.html