Homebrew PCBs

On Fri, 15 Aug 2014 12:52:18 -0400, you wrote:

>Hello Harvey,
>
>I'm interested in getting more information on your drilling setup, 
>mostly the optical stuff - camera, software, monitor. What supplies 
>the reticule image for the crosshairs?

OK, in short.  The optical stuff is a 12 volt/24vac camera with almost
any lens that works well.  You want to move it out away from the CCD
so that you have the equivalent of a closeup extender.  

That goes to a standard color monitor.  This is an LCD monitor that I
found (runs off 12 volts DC), and has an overlay with a graticule on
it.  I've been tempted to make it more complicated by adding a
crosshair generator, but that'd be another PC board and some video
work.  The graticule is easier.  Just make the pattern on a
transparency and put it over the monitor itself.  Almost any old TV
would work.

The software is custom, and is a simple Z axis setup.  There are two
pushbuttons (green/red) and a rotary encoder with a push switch
(Electronics goldmine sold them).  There's an end travel (and top
travel) led sensor.

Boot up, the display says to push green to home.  That homes the drill
and runs it up to the rest position.  pushing the footswitch (or the
green pushbutton) starts a drill cycle, three speeds possible, up to
the drill top position.  At that point the drill retreats back to the
rest position and turns off the Proxxon tool (solid state relay, works
better with the 12 volt model and transformer).

Pushing the red button puts the drill at the top position, which is
where I can change the bit from the top.

Pushing in the rotary switch/encoder put it into an adjust mode, where
I can set the rest and top positions (stored in the processor's
eprom).

Basically, the software is not all that complicated, but does rely on
an infrastructure of display drivers (it's a smart display that I
built), a modified keyboard driver package, and a few other bits and
pieces.

Physically, the camera is mounted on a PACE hot air station stand (I
managed to find two for not so much money), which gives me an
overarching arm for the camera.  I can move it up and down to focus
the camera and move it out of the way for drill change.  I suppose
another enhancement would be to put a stepper drive on that.

You will have to align the camera center point to the tip of the
drill.  In my case, the adjustment is entirely mechanical, with the
camera swinging left/right on the mounting screw, but tilted (spring
used on screw) forwards/backwards as needed.  That's a trifle awkward,
and the electronic crosshair generator would be better.  That would
require a small CPLD, a sync separator, a synchronized pixel clock,
and some counters.  Ideally, the graticule has ticks on both axis
lines, since that helps align the center of large holes.

The smallest hole I drill is 0.021 for a via, and I estimate that I
can repeat that hole to within 0.002 inches roughly.  The size of that
hole on the monitor is the critical part.

You'll want to backlight the board.  Red light may be most useful, but
I haven't experimented with that yet.

Hope that this helps.

Harvey


>
>Thanks.
>
>Mark