Re: [CAD_CAM_EDM_DRO] Project on a miniscule budget

Paul,
The simplest (but not by any means the most effective) is the
solenoid suspended type. Pass a current through the coil and down
through the electrode. As the workpiece falls the current increases
and the solenoid pulls the electrode up away from the workpiece until
it breaks the current. If you get the weight of the workpiece and the
windings on the coil right it will bounce up and down quite happily
sparking away and in theory removing metal. Its simple and easy to
build from scrap bits and pieces but don't expect it to do too much.

The articles by Roy Amsbury are in ME Vol 142 no 3541 and 3542 with a
follow up letter in 3549. It was called "A Spark Erosion Machine".
Sorry I have no idea what it is about but my mags don't go back that
far.

Regards
Bill Phillips

>Here's one to challenge all of you!
>
>I need to put a 0.1875" square hole along a 1.25 inch length of a
>0.250" square BMS bar. I need this hole to be a lapped or precision
>fit on 0.1875" square bronze slipper. Fabrication using silver
>soldered joints is a possibility but so far I have not been able to
>produce these components with the fine finish I need for the job...
>An EDM machine came to mind and I would like to have a go at making a
>simple one if that's possible.
>I am retired here in the UK and have little spare cash but as an ex
>audio engineer and film sound recordist I do have some knowledge of
>electronics.
>I know there was a circuit for a very simple machine in Model
>Engineer magazine many years ago (1970's I think) but tracking the
>issue and a copy down has been fruitless so far even through the now
>owners of the publication.
>I believe the designers name was Roy Amsbury who worked for Rolls
>Royce in Derby but I have been told he passed away some years ago.
>Just wondered if anyone has a simple EDM machine design that they
>might be prepared to let me have. Could be an interesting project to
>pass the time away with.
>Regards to all
>Paul Miles.
>