Homebrew PCBs

I described setting up a web cam to view the bottom side of the PCB 
while drilling from the top side.  I use a sacrificial piece of plastic 
that I drill first so it indicates exactly where the drill is hitting.  
That eliminates a host of problems such as boresight error.
Please see:
http://tech.dir.groups.yahoo.com/group/Homebrew_PCBs/message/28429
and I put pictures in
top drill-bottom view drill press.pdf 
<http://f1.grp.yahoofs.com/v1/gLKMT4q13XDxiIgzZmifkT0BbqsHILZSk-F9mp_Cbr7hpFKpq63z_9WqZR4coro9pOPQAfkru-t0SpL73lbMtWYcu0eHtV598w/top%20drill-bottom%20view%20drill%20press.pdf>
in the files section.

On 4/16/2012 3:39 PM, Simao Cardoso wrote:
>
> bebx2000 wrote:
> >
> > Could anyone offer an opinion on this drilling fixture?
>
> Hi, i remember some old discussions on this list about a drill press
> that I could never understand how it works, until saw that image. I
> tried to search the thread but i lack time right know.
>
> If i understand it right, and in my modest opinion, it intends to drill
> the single sided board from the non copper side, because the drill bit
> tends to slide if drilled from the copper (if it hasn't a etch hole for
> drilling) and avoids the annoying burrs on copper. It has a light to
> illuminate the bottom side of the board and when it cross the glass it
> will behave like a mirror to your point of view, because it has more
> light from the other side, and you see the down side of the pcb with the
> alignment hole. There are who adds a mirror so you can see the bottom of
> the pcb from above, in a comfortable position.
>
> But i, before the cnc, just bought a proxxon drill stand and both a
> collet chuck proxxon spindle for carbide bits and another with 3 jaw
> keyless chuck from proxxon too for hss and other tools. All the pcb's i
> hand drilled had the etched hole, never went through this.
>
>