Bench Top Spark Eroder

Charles,

Send me a photo - I suspect that is the same model that I ebayed last year before my abortive house move

AWEM

Thanks Andrew

Here's a photo

guidance

Yes that is exactly the same model. A very simple system using water dielectric in a total loss sytem, and the buzzer principle to control the electrode rather than a servo and hv generator.

The weight of the electrode and its mount extend a spring until the circuit is completed between the electrode and the work. At this point current flows through a solenoid coil surrounding the electrode mount, which is pulled upwards by magnetic attraction. This movement breaks the circuit, and the back emf of the coil as the magnetic field collapses creates a spark that does the errosion. As the coil is no longer energised the electrode falls again under gravity and the cycle repeats.

The electrode is a thin walled copper tube, and an electrolyte reservoir fixed on top of the machine releases water slowly though it to flush away the eroded material and keep it cool.

Good for removing small broken taps or knocking holes in hacksaw blades but not much else. The sparking conditions that this type of eroder creates are carefully avoided in diesinking types of EDM machines by significantly complex electronic monitering systems.

AWEM

Used that model before to save my ass on a few occasions!

We always made our electrodes solid at the business end with a cross hole just under the threaded section to allow the water to dribble down the outside.

I'd like one myself oneday, just in case!

Wayne....

Thanks Andrew and Wayne (and yes Wayne - I also acquired it to save my ass when needed) I'll give it a good clean and see if it works at the weekend. I may well be back with more questions.

Charles

Camden Books has two books about building a EDM. This one is the primitive version: "Build a Metal Disintegrator".

lists 3 Books about EDM. The first one is the one noted above, then directly following a more complex (stepper, electronics etc) and then a how-to.

Nick

Thanks Nick

I'd forgotten about that one. There was also a design for a simple one in Model Engineer's Workshop a couple of years ago.

Charkes

There's a good exposition of a home-built EDM at the superb and remarkable Model Engine News site at .

Hth,

Do have both booklets. I bought them out of curiosity. The primitive one (it is, and it isn't a blame to call it primitive) is just a vibrator (for engraving) and a bit of perspex and steel, transformer and a rectifier (IIRC). Ideal for tap disintegration. If you want, I can describe it a bit more.

Nick

Thanks. Makes me want to make one.

It did. :-)

Nick

Thanks for the offer Nick but I think that I'll have a play this weekend and see how it goes

Charles