Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
> Hi Curt,
> 
> So the raster is scanned dot by dot no matter if cutting is needed,
> and   with no regard to if the cutting is finished?

Using 1 oz. copper board I can burn a 1 mil dot with one pulse and
finish an entire 8 x 11 inch board in under 45 minutes.


> That is a good KISS approach, and if you go slow enough there should
> not be problems.
> However in the future there would be speedup potential.


At this moment I'm just happy to have the basic setup working and
producing boards!  There will be time enough for refinement after I
get it debugged.


> Also, i didn't mean to use the groundplanes for return, i thought
when you  
> have large copper areas you might just move over them fast and not
need to  
> scan it slowly if there is no cutting to be done.
> 
> I think the software should not be too hard to do, esp. if one uses
a  
> picture with the correct resolution already.


I agree but right now I want to "crawl before I walk"  Right now I'm
working storing the results of a 1000 dot per inch black and white
scan in the controller.

News Flash!  Philips has just released the LPC2148 with 512kb memory
AND USB 2.0 compliance.  This should allow direct connection of a
scanner to the controller to download artwork from any source ( ie
magazines or books in addition to CAD files ).
 
> You know, if someone would find a good plotter pen or inkjet head i
could  
> even do the componet legend on this machine. Wouldn't it be great to
do  
> _all_ PCB work on the same machine? Now... a solderpaste dispenser
and a  
> pick and place head... okok i'll stop dreaming, those things are for
later.
> 


I worked on this with an HP 7550 using different sized "pens"
(electrodes).  As I noted elsewhere using vector graphics increases
the theoretical speed by reducing the amount of cutting but increases
the software load needed to insure a pulse return path.  Using raster
graphics just works.  Good enough for a first prototype.

I was thinking of using a tapered tube with needle in it's center to
dispense solder paste ( or One Shot Sign Painters enamel? ) in
controllable amounts.  Maybe later ;D


My next focus will be combining the electrode and a drill on a single
spindle to allow etching and dust free drilling in one setup.


Stephen, I'll try to get pictures and DWGs of the mechanical setup up
on the net after the July the 4th holiday, but I think your machine
should work just fine as a base for EDM.

Curt