I've just acquired a small bench top spark eroder in need of some TLC
(at the very least). The label proclaims
"Walton Electronics Ltd 'Arc-out', 240 volts"
I don't suppose that anyone has a similar item or has any guidance to
the set up and usage of this type of equipment?
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
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.
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
I'd like one myself oneday, just in case!
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.
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.