Homebrew PCBs

Baxter,

Your insights are very helpful. I had the same problem with too much light
washing out the beam and too little light not letting me see the area and
drill bit. I now understand why a laser is needed and a high intensity LED
is not bright enough. It is too bad the laser beam couldn't be narrow enough
to match the diameter of the drill. Then there would be no question about
where it would hit.

I did think about some electrical way to tell when the drill was centered in
the hole. But it would require me to move a probe to each trace and that
would be a PITA. I wonder if something like a sewing machine foot could
work. It would be a half circle supported by a spring arrangement. The goal
is to minimize parallax and speed up the drilling. 

Rick

-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of bebx2000
Sent: Thursday, January 03, 2013 1:59 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: circuit board drilling question



Rick,

I look down at the board at about 45deg in subdued room lighting. When the
beam is hitting copper you don't see any thing. when it shines on etched
areas you see a spot. When it is under a pad with an etched hole you will
see the spot. Then adjust the board in the horizontal plane with tiny
movements for the greatest spot intensity; then drill.

This drilling setup is not an original idea. I came across the concept from
a forum post using a cigar box. I use a Proxxon drill stand with a Proxxon
hand tool and there wasn't enough room for the cigar box so I adapted it to
a smaller box (4" x 3" x 1 1/2"). I am using a $5 dealExtreme red laser
module directly hooked to 3 AA cells. A $2 Staples steel ruler was cut to
fit in the bottom of the box and glued. The laser is held with a large paper
binder clip which is fastened to the the ruler with small button Neodymium
magnets. The 45 deg mirror was fashioned from a piece of 1/2' 90 deg
extruded aluminum stock with a craft store 1/2" strip mirror glued to one
face. The mirror is held in place perpendicular to the laser with double
sided sticky tape. I used magnets to secure the laser to make it easier to
adjust it relative to the mirror and the hole in the top of the box. This is
a real jury rig, but it seems to work ok.

Baxter
> I put my drill press rather high and sat on a low chair so my eyes are 
> about even with the pull handle. How do you sit so you can see the action?




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