Homebrew PCBs

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
>>