About me.
I am 72 years old and live in the UK. I was a toolmaker by trade mainly working on multi progression press tools running
in Bruderer high speed power presses but now I am retired but still self employed. I have recently made a 3 Axis CNC coil winder
to do some sub contract orthocyclic coil winding (Parallel winding). I have a milling machine, lathe, surface grinder, injection
moulding machine, a couple of fly presses and as you will see an Agietron EDM machine. I'm a flightsim nut flying an F/A-1E in my
spare time. I have had a couple of strokes in later life so for me to keep uploading pictures and info via emails would be difficult
so I thought that I would do a web page I can update in my own time so that you can see what I am doing. If you have any questions or
comments I will try and respond but there might a delay.
Many years ago I brought an Agietron AA05 desktop EDM machine. This machine and the power supply was manufactured in 1966. At
first it did not work. By that I mean the electrode spindle would not go down or up under power. I could move the electrode spindle
with the hand wheel at the top of the head. I contacted Agietron in Switzerland, not to expecting a reply, but they sent me all the
circuit details for my actual machine. They had scanned the actual blueprints of the circuit so the images were very dark. It took
me several weeks using Paint Shop Pro 7 to clean up the circuit details. I found that there were 2 pots that did a sort of balancing
act to monitor the voltage at the gap. I moved them to the front panel so that I could alter them more easily and connected a volt
meter to each to monitor the voltage . Finally I got it to work but it was very hit and miss. Additionally some of the switches are
worn and at some power settings start to arc.
In May of 2015 I started looking on the internet to see if you could buy just a power supply or possibly diy circuits. This is
when I found Ben's book. I brought the book and later brought the PCB from Ben. I then set about buying all the components for the
circuit either from Mouser UK and other UK sources.
As I read the book I realized, at the time, that the brushed DC servo motor on my machine might too powerful to be driven by the
new electronics. Later and many ideas for driving a 120V DC motor via a 12V DC source including relay 'H' bridges but eventually
I found that the motor will run at 4V DC to up to 120V DC at 0.12 amps so I will try a direct connection and see what happens. I
set up a test and set the machine to spark a job and monitored the voltage across the brushes. Previously I monitored the voltage
in the power supply that was part of the voltage balancing system. I found the ideal sparking voltage setting (Speed) was 11.2 volts
if I turned it down any farther that 10.5 volts the voltage across the brushes dropped to 0 volts. This is due to the speed pot and
not the servo motor. The motor has a field coil,not a magnet, which was supplied with 15 V DC at 0.5 amps. There is also a electro
mechanical clutch that is sprung against the hand wheel in manual mode. The clutch needs 18V DC at 0.6 amps. (Will run at 15 VDC)
When the start burn button is pressed the clutch is energized to press on the gearing from the servo motor to drive the electrode
spindle up or down.
I setup an experiment to see if I could run the servo motor at 12V or less DC and at no more that 1 amp. The motor's name plate
states 14/120V at 0.5 amps. This experiment was successful, both up and down, running below 0.15 amps but because I had disconnected
the motor brushes but it would be better if I can supply more that 12V to the servo motor just if case, the clutch coil and field
coil from the original circuit the power to the electrode would not turn on.
Here is the original circuit for this machine.
May 2015.
I purchased all the components as per Ben's list (Version Pulse 2.0A) with some additional components due to the fact that I
am starting with an existing EDM machine with it's own controls. I will detail these additions later in the build and explain how they
interface with Ben's design and the machine but basicaly I have to interface with an electro-magnetic clutch, to engage the hand wheel
or servo motor, the servo motor field coils and a dielectric level gauge as the existing electrode power will not turn on unless the
level of the dielectric is above a mechanically adjustable level, I want to retain this feature due to the possible risk of fire if the
dielectric level falls below the electrode.
Physical start of the power supply
22-09-17.
Most of the bolt on parts are bolted down except the PCB, just positioned where it will be. It will be on nylon
standoffs. Hole 16 in the PCB will be earthed to the base plate. I think this is right?. It is the hole on the PCB to the
right nearest to you in the L/Hand photo below. My machine is earthed so either PP1 or PP2 on schematic will be earthed depending
which polarity is used.
24-09-17.
15 VDC Power supply added to power the Servo Motor
field coils and Hand / Servo clutch with associated control relays
added.
30-09-17. Power supply lid drilled and most of the switches / pots in place. Above is a machine interface circuit to Ben's circuit
30-09-17. PCB stuffed and the power wiring double checked and done.
Next jobs. -
Finish wiring and label switches. Think through machine interface circuit to PCB with respect to S7 (Manual up/down)
and "servo" circuit" on Pulse 2.0A schematic. My thoughts are to set it up with a 12V motor similar to the one in Ben's book so
to see if the original circuit works, then modify it to work with my machine.