Re: [CAD_CAM_EDM_DRO] 2D printer-real parts

Alan Marconett KM6VV wrote:

> Joe, Ian,
>
> check out Jon's photo plotter:
>
> http://www.artsci.wustl.edu/~jmelson/photoplot.html
>
>
> He uses a laser diode to expose hi-res film, from Gerber files, as I
> understand.
> Now if we could get him to share a little more of the details! ;>)

This was a 10-year project, with a number of false starts, mostly
waiting for diode
lasers to become available. There are exotic servo systems that a
number of
good engineers says could never work. (I have to take a signal from a
1024-line
encoder on the rotating drum and multiply it by 20 to generate the pixel
clock.
It does work, but it wasn't easy!)

There are some optical tricks to get a .001" gaussian spot with a long
working
distance and good depth of field. The litho film has a very thick
emulsion layer,
and the depth of field of 10 X microscope objectives is significantly
shorter
than that thickness!

I had to replace the cheap ballscrew with a precision anti-backlash
screw to
get rid of the slight positioning errors that left light and dark bands
in the film.

The software was a VERY big job, and it still has some deficiencies.
But, it does
work!

I had planned on selling this machine for about $10,000 each (as a
Lavenir goes
for about $40,000, and a Gerber goes for $100,000 and up (Way up!)
But, there are so many regulatory hassles involved in making a product
that
has lasers, rapidly moving parts, etc. that I just haven't gotten around
to
trying to market it.

Jon