Hi Curt,
Good to hear from you again.
>--- curt_rxr <cwrxr@...> wrote:
>
>Roger I used brass wire and distilled water and had
>arranged the servo
>circuit to feed the wire via a pinch roller and worm
>screw drive. the
>servo circuit is as per the NASA / Garden of EDM
>circuit.
I am in the middle of designing an electrode feed
system similar to yours. I have not heard of the NASA
circuit, is it some sort of servo drive?
>Roger the gap breakdown voltage controls the gap via
>the servo. As
>the electrode ( brass wire ) advances the gap closes
>until the spark
>after which the electrode retracts so the system is
>ready for he next
>spark.
If I understand this right you are initiating the
spark by advancing the electrode and retreating it at
each point. How does this keep up with your scanning
speed of approx 20 inches/sec? Or have I totally
misunderstood the operation of the servo?
My early experiments included a solenoid armature
oscillating an electrode at 50 Hz, amplitude about
1mm. This worked very well since the spark always
initiated at the dielectric breakdown point. However,
at the moment I can see no way of integrating the
electrode feed with the solenoid arrangement. If I
could it would answer a lot of problems.
>Hi Roger,
>
>I'm glad to see someone making progress. My system
>is stalled at a
>pulse repetition rate of 200,000 per second using
>IGBTs designed for
.auto igniton system. That rate gives me about an
>hour and a quarter
>processing time for an 8 inch by 12 inch PCB >using
.001 inch brass wire
>as an electrode. It makes a real nice board, but I
>can use Toner
>Transfer and CuCl2 bubble etching to make five boards
>in the same time!
>
>I'll be interested in your advances to the art, but
>right now it looks
>to me like the direct print inkjet system will
>replace TT and EDM for
>homebrew PCB prototyping.
>
>Curt Richards
My boards are all 4 x 3 inches, but the attraction of
EDM is it is the cheapest way to go, and it can be
left on its one to process with virtually no board
preparation, and no ink or etchant costs.
Roger
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