Hi, Roger.
Sounds VERY cool. For electrodes, have you considered mechanical pencil
lead. I have found the B hardness (fairly soft) to be a good conductor
and it is available down to 0.3mm. I know that graphite electrodes are
often used in the "real world."
Donald.
Homebrew_PCBs@yahoogroups.com wrote:
>
> Message: 5
> Date: Tue, 2 May 2006 18:57:22 +0100 (BST)
> From: roger lucas <ralucas4277@...>
> Subject: Re: PCB EDM MILL Initial Tests
>
> Hi Stefan,
>
> I know that it should have worked in theory, but I was
> surprised at how well it actually turned out.
>
> I tried with tinned copper wire and a tinned steel
> sewing needle (purloined from my wife's needlework
> box), essentially the wear was about the same for
> both. The eroded pixel diameter is directly related to
> the electrode dia, as the sewing needle eroded the
> pixel became larger.
> I need to try to obtain some half hard or hard 10 mil
> brass wire for the next trial.
>
> The setting of the spark parameters before sparking is
> essentially to eliminate the uncertainty of whether
> pixels have been fully eroded or not, especially where
> electrode wear is high. I might just try some broken
> carbide drill bits, the tungsten might resist erosion
> better, trouble is carbide only goes to 0.5mm dia.
>
> Will post some sample photos after next revision and
> trials.
>
> Roger
>
> --- Stefan Trethan <stefan_trethan@...> wrote:
>
>
>>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
>>