Homebrew PCBs

If you have not already come across this group, you may find it
helpful for EDM experimentation. 

http://tech.groups.yahoo.com/group/EDMHomeBuilders/

I bought a copy of the moderators book on homebrew edm and it is very
good. Several people have built his design and have pictures in the
photo section. I hope to build one of my own at some point , but not
for pcb edm purposes.




--- In Homebrew_PCBs@yahoogroups.com, "ralucas4277" <ralucas4277@...>
wrote:
>
> Hi Curt,
> 
> After your previously posted details of your system, I carried out some 
> more tests on pcb spark erosion. What became immediately clear was the 
> requirement for an accurate wire feed for the electrode.
> 
> I put together a mall stepper driven wire roller feed mechanism, using 
> a gearbox and a butchered capstan mechanism from an old tape recorder, 
> with fixed orifices above and below the vertical roller wire drive, 
> thus giving the step in/out for the spark initiation. This worked using 
> 10 mil wire, (smaller dia wires are more difficult to source easily in 
> small quantities in the UK, if anyone knows better, please let me 
> know), but the need for a more precision unit was needed, and other 
> things intervened. I bought a micro lathe intending to put together a 
> higher precision unit. A servo motor rather than a stepper may give a 
> speed increase.
> 
> The reason that I still intend to develop this system, is that direct 
> printing is, as far as I can tell, still a bit of a black art, (and I 
> never really got toner transfer to work reliably 100% of the time), the 
> inks are expensive to import to the UK, you still need to etch, and you 
> have to modify a printer anyway.
> 
> PCB EDM can eliminate these costs at the expense of speed, whilst 
> simultaneously using a mini cnc for drilling and etching.
> 
> If the feed wire mechanism can be made to work at reasonable speed, I 
> think that the next bottleneck would be the turn on/off times of the 
> spark controlling mosfets. I thought that this could be overcome by 
> using multiple spark generators sequentially fired, if necessary.
> 
> Of course, the whole thing may be constrained by the speed of the cnc 
> machine used, but then this whole approach is not really a problem when 
> the machine could run in the background unattended. Speed is as 
> Einstein pointed out relative anyway.
> 
> I intend to do some more development this summer. Is anyone else 
> interested in this approach, do you think?
> 
> Good to hear you still have an interest in the method.
> 
> Roger
> 
> 
>  
> 
> 
> 
> --- In Homebrew_PCBs@yahoogroups.com, "curt_rxr" <curt_rxr@> wrote:
> >
> > Hi all,
> > 
> > When this list first started, I posted about my attempts to turn an HP
> > Deskjet into an EDM machine for PCBs, but I abandoned the project
> > after Stefan and others developed toner transfer into a reliable
> > system.  The EDM was just too slow compared to TT.  I've moved on to a
> > modified Xerox Phaser printer that puts wax directly on a thin sheets
> > of epoxy PCB and allows me to 'print' my board and etch it rapidly.
> > 
> > I know that Graham and others kept up the work on EDM and I was
> > wondering if anyone on the list had made any breakthroughs?   I still
> > think that there must be a way to reliably generate pulses fast enough
> > to create a PCB in a reasonable time, especially if a drill head was
> > incorporated to allow drilling and 'etching' with one setup.
> > 
> > Curt
> >
>