Good to hear you got such good results.
I don't have any specific concerns why it would not work, never had after
some manual tests with a simple power supply.
But i don't currently have the time to build a CNC, although i have most
components set aside for a while now.
The electrode erosion thing was discussed back then, if i remember
correctly the thinking was that one would advance the electrode until a
spark of the correct voltage is occuring. One would need to decide if the
energy was sufficient to blast out the pixel or if it must be re-done.
But your approach seems a good idea also.
Keep us updated, i definitely plan to build the CNC but it will be months
for sure. If i use it for drilling of inkjet printed PCBs or if EDM will
be an option is to be seen.
what material is your electrode wire made of?
ST
On Tue, 02 May 2006 18:07:19 +0200, roger lucas <
ralucas4277@...>
wrote:
> Well, I finally motivated myself this holiday weekend
>
> to get my PCB EDM lash-up to cut copper, and, YES, it
>
> does cut clean lines thru the copper without board
>
> burning or marking. Shine a torch through the tracks
>
> from the rear of the board and there is a faithful
>
> line of light, (no firstborn goats or pentagrams
>
> neccessary).
>
>
> With my highest power lens and head magnifier I could
>
> see no trace of copper whiskers on the EDM'd track.
>
> Interestingly, the copper is blasted away entirely
>
> below the cross section of the wire, there is no
>
> 'erosion bleeding' into the surrounding copper outside
>
> of the wire dia.
>
>
> Have only cut straight lines so far with 26 swg and
>
> with a 0.2 mm step increment, (need to modify the
>
> stepper gear ratio), and with multiple (continuous)
>
> sparking between increments, (no on/off sparks or
>
> raster yet).
>
>
> One significant problem has emerged which Curt
>
> Richards did not address, (or if he did, he did not
>
> mention it). The wire electrode erosion is
>
> significant, and will require an active Z axis
>
> correction to maintain as consistent a spark gap
>
> distance as possible between the electrode and pcb
>
> surface. To do this I will insert a routine to 'touch
>
> down' the electrode on the copper to zero the gap,(no
>
> spark, closure sensed by two PIC output/inputs for
>
> voltage present), and then retreat the electrode to a
>
> standard clearance before any track eroding is
>
> commenced, (Andrew, this is why I need the BMP byte by
>
> byte transfer). This will also tend to compensate for
>
> any board distortion.
>
>
> Used tapwater as a dielectric with no problems, (the
>
> modified Garden of EDM circuit controls the
>
> electrolysis with no problems).
>
>
> Curt controlled his spark discharge voltage by
>
> dynamically adjusting the electrode gap on the fly. I
>
> think that for pcb work this is not the correct
>
> approach because of the wire erosion problem, since
>
> one needs to KNOW the gap distance AND available
>
> discharge energy BEFORE discharge, which is why I am
>
> going for the touch down zeroing method, (slower but
>
> speed is not significant at the moment). The discharge
>
> energy will be set by presetting the voltage level
>
> required and capacitor selection, (simple comparator
>
> control integrated into the spark control). I think
>
> this is the secret of successful pcb edm'ing.
>
>
> This is really looking as if direct raw copper board
>
> to finished pcb is going to be possible.
>
>
> Roger