If you want large acrylic plastic tubes, check out eBay. Look for "Clear
acrylic Plastic Plexiglas Pipe tube". This vendor sells 4 and 6" diameter
pipe in foot long segments.
Andy
_____
From:
Homebrew_PCBs@yahoogroups.com [mailto:
Homebrew_PCBs@yahoogroups.com]
On Behalf Of jmelson2
Sent: Thursday, March 03, 2011 7:11 PM
To:
Homebrew_PCBs@yahoogroups.comSubject: [Homebrew_PCBs] Re: Kodak PRD film ?
--- In
Homebrew_PCBs@yahoogroups.com<mailto:Homebrew_PCBs%40yahoogroups.com> , "designer_craig" <cs6061@...>
wrote:
>
> John,
> Thanks for the info, that is exactly what I was thinking but will most
likely use some aluminum tubing for the drum. With the size and cost of
memory these days I was planning on using a little Atmel uP possibly
assisted by a FPGA to buffer up a full sheet worth of data prior to writing
the drum.
>
> My initial thoughts were something like 600 dpi do you find you need the
1000 dpi?
Yes, if I could have found the right size aluminum tube, I might have used
that to start. Something slightly over 6.5" just didn't seem available. I
guess I could have rolled some thick sheet, but even the roller at work
probably could not have handled 1/4" thick aluminum.
A 12 x 16" sheet of film would take 192 MB of memory. What I would probably
do now is either use the parallel port in DMA mode, or use something like
the Cypress FX2 (EZ-USB) chip (a fast USB chip that is marginally
programmable, and can stream byte-wide data at incredible speeds. I got one
at work, I wasn't able to program it to do what I wanted, but I think it
could run a photoplotter pretty well.
Note that my photoplotter as it is cranks out a pixel every 5 us, so even as
8-bit bytes, that is 625,000 bytes a second.
Yes, the 1000 DPI is really marginal for PCB work, I routinely make .008"
lines and spaces. Even the cheap photoplotters do 2500 DPI and the more
expensive ones are 10,000+.
Jon
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