Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Andrew" <andrewm1973@...> 
wrote:
>
> >> Roel CNC wrote:
> >>
> >> i like the idea of making me own laserplotter.
> >> tested: a pointerlaser (some cheap thing)
> >> with an extra focus lense, a red sensible
> >> film gave me super fine lines (close to a
> >> single cloth fiber).
> >>
> >> did any of us fouling around with this idea !!
> >> 
> >> tips and suggestions always welcome:)
> >> 
> 
> > Roel also wrote:
> > Hi all, 
> > M i started this toppic - got lots of replys
> > on it with ideas :)
> > 
> > i gonna use Cunningfellow's pll thing some
> > stepper for the laser and a dma-16 card -
> > high speed dio card up to 250kB/s some code
> > compiled (TPascal)that eats the the 274 (gerber)
> > files and output to the drum
> 
> Roel - I have done a bit more work on the PLL
> thing.  That one posted so far was just a test of
> concept / prototype.  There are a few things
> un-needed and a few other things that are needed.
> 
lots of schematics on the net for pll that can be used i think 

> It was built to do some tinkering with a
> commercial DC servo motor I had lying around.
> I finally want to just use a DC brushed motor
> with some optos ripped out of mice (to make it
> easier for others to get parts to build)
> 
> Also - I was planning on getting the data out of
> a USB port (via an FT232) instead of some custom
> hardware in the PC (again ease to duplicate).
> 
> The FT232 can do 4 Mb (which is same ballpark to
> 250 KB).  However if you compress the 1000dpi
> data even with a simple algo like G3 fax you can
> fit the data stream down 100 kilo baud (assuming
> 1000dpi and 10" x 10" board in 10 minutes)
> 
> I have sourced some toothed belts and linear
> shafts for moving the laser head.  I have also
> found a source of cheapish lasers that can be
> focused down to small enough dot size if I can't
> find a simple repeatable solution for people to
> do the same with a cheap laser pointer.

i was thinking to use a ldiode from a dvd burner they 
can trow up to 70mw and with a good lense a super ultra thin line
> 
> Very interested in your thoughts on the carraige
> part.  You seem to have a lot more experience
> than I with CNC things (and PVC etch tanks).

> Do you think at 1000 (or 2000) DPI that there will
> be a sticktion problem?  Do you think the tooth
> belt idea is going to be good enough or do you
> think that I might need to use a very fine pitch
> leadscrew?

a lead screw for this job will be expensive i think
first touhts was to use a beld but after some thinking 
a steel wire is super stiff and easy to gear 
> 
> I have done some software on the PC to read a
> BMP file compress it and send it out to my
> hardware.  I was just going to use and external
> gerber to BMP thing.  However - I have no
> objections to reading geber directly if you would
> like to work together on the project.
> 

> The only other though I had from the PC side
> was to maybe write a GDI driver.  That might be
> a bit out of my league though.
> 
> andrewm (or cunningfellow to some)
>
email me if you like Andrew or maybe msn its faster hey'

gr Roel