Re: Fwd: Re: [CAD_CAM_EDM_DRO] Re: direct printing PCBs

On Wednesday 16 August 2006 13:36, Graham Stabler wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Sebastien Bailard - Dubsen
>
> >.. Do you think you'd be able to design most of the parts for a
> > standalone system to be RP-able, or at least EDM-able?
>
> I don't think there would be any point trying to design a wire EDM for
> RP or even EDM contruction without first having built one using normal
> contruction methods. The other question is what do you expect it to
> be able to do, what size components? What thickness? What accuracy?
> What speed? Remember that the typical wire in EDM is 0.25mm and the
> typical spark gap is much smaller than that, your motion needs to be
> steady enough not to vibrate the wire and cause shorts. Do you really
> expect a dielectric system to be RPable? Would you want to make pumps
> and filters? The wire tension and speed needs to be regulated, the
> spark gap monitored and the feedrate controlled and even reversed on
> the fly. The power supply needs to be powerful and for speed be
> pulsed (something few DIY EDMers have played with).
>

I'm imagining a workpiece that's 10cmx10cmx1cm. For RepRap, we're aiming
for .1mm repeatable positioning, although people are going to work to improve
that figure after the 1.0 release.

Pumps and filters - eventually. We've got a working peristaltic pump, but
nothing with a rotary impeller yet. Filters - I don't know, we might be able
to bodge something together from activated charcoal and kimwipes (low dust
wipes for lab clean up), held in rp'd canisters, like a brita filter
cartridge.

I think you may be right about building one first with normal construction
methods - although it depends on the your available tooling really. Perhaps
the pathway would be to make a metal one, then slowly replace all the parts
with RP'ed and EDM cut pieces. It could be thermoplastic doesn't have the
mechanical strength to do it, in which case you'd want to go with RP'ed
ceramic or metal, either sintered extruded slurry or lostwax/slipcast.

Regarding the mechatronic aspects, you'll confront those no matter what
fabrication method you're using.

Much of this will seem more realistic once we've got some working RepStraps.

> > Maybe we'd want to go with a edm machine that could, along with >
> >parts from a reprap, reproduce.
>
> Well it would make a change from it reproducing with itself ;)
>

Everyone needs a hobby. Mine is quite enjoyable.

> Graham
>

Regards,

-Sebastien