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Drill Table Controller |
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One of the Holy Grails of the home electronics hobbyist is the ability to produce
usable printed circuit boards (PCBs) at home. Unfortunately, there are many obstacles
to reaching that goal. There are lots of nasty chemicals and expensive machines
involved in PCB production. Even if the problems of artwork generation, resist,
etching, plating, solder mask, silk screen, etc., can be overcome, there is one task
that is unavoidable: Drilling Holes. Whether it's sitting for hours in front of a
drill press, or worse, holding a screaming Dremmel tool in your sweaty palm for what
seems like forever, this is one of the most boring and unpleasant parts of the process.
What's more, one slip of your bit can rip up a pad or a trace, forcing you to rework
the board later.
A friend of mine (who pursues this particular Holy Grail somewhat more zealously
than I) had been amassing pieces and parts with the idea of building a computer
controlled drill table. When he finally announced that critical part-mass had been
achieved, and that construction was ready to begin, I offered to build the controller
for it. This seemed like a fairly trivial part of the job, compared to the mechanical
engineering and precision assembly required for the drill table itself, but non-trivial
enough to give me a little "ownership", and hopefully, access to the completed
machine.
The design of the controller was fairly simple. All it had to do was read in an Excelon
format drill file (produced by most CAD packages) via a serial port and drive the stepper
motors that control the X,Y, and Z axes of the drill table. I even added an LCD display
for the operator interface. This wasn't strictly necessary, but it was another case of
hardware just waiting for the right project to come along. After building up
some power drivers for the motors, (former Micro Dynamics
employees may recognize the plate that I used for a heat sink) I was ready for some
preliminary live testing. I took the stuff over to my friend's house and hooked everything
up to the partially completed drill table. Sure enough, after downloading a small test drill
file, motors and lead screws started turning, pausing at each imaginary drill location. The
actual drilling mechanism wasn't done yet, but it was pretty damn cool, nonetheless.
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| The Drill Table Controller |
Stepper Motor Drivers |
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| LCD Informational Display |
Unfortunately, the drill table was never completed. I guess the appearance of a few
relatively inexpensive (still not cheap enough for me, though!) prototype PCB shops
made the whole home-PCB thing seem not worth the trouble. After all, there are still
all those other problems (mentioned above) to overcome. Still, it's a pretty impressive
piece of work to give up on. Maybe instead of a drill, we could put a router on there
and carve 3-D stuff. Anyway, let's just say that whatever it is, it's just not done yet.
The Drill Table?
