Homebrew PCBs

On Thu, 27 Jan 2005 15:07:12 -0000, onenastyviper  
<oneNastyViper@...> wrote:

>
> Hi, I have recently rescued a HP 7475A plotter and I am looking at
> converting it to handle pcb scratch etching (I think the mechanism is
> nowhere near strong for milling).
> My question is do any members have any good links or files on scratch
> etching?
> I am thinking either direct copper-scratching (styluses??) or
> scratching though an etch-resist and etching the board as normal.
> Has anybody tried this?
> What type of results did they get on track resolution??
> regards, PK


track resolution with a OHP pen (staedtler) was bad, here.
couldn't even get a trace between DIL pins, and the width is inconsistent  
because it depends on how fast the pen moves.

I never tried scratching a resist, but my suspicions are that it has  
similar drawbacks as milling in terms of speed and result.

As for tt we takled about, i think a old printer at ebay is cheap enough  
not to bother with the plotter method.
I'm not one of the usual nay sayers (hi mike ;-) ) but i have tried it and  
have had bad results. Problems seemed unresolveable so i abandoned the  
method.
Now the weakest link on bbc is about to begin, so i'll leave it at that.

ST