Please help me understand 50 year old wiring diagram of our machine

Thread Starter

ads295

Joined Jul 9, 2020
2
Hello all

This is my first post and I hope you will help me.
I am a novice at understanding electronics. I'm more of a mechanical guy but I know basic electronics (Kirchhof's law, power and voltage calculations, etc). Mostly academic.
Now I have to understand these diagrams of a machine in the company I work at. It is 50 years old. It is a machine that drills small holes in a part of very small size (0.2 to 0.4mm) through spark erosion. The idea is to create a potential difference high enough to ionise the space between the charged wire and the part, causing it to erode the material little by little.
Unfortunately my limited knowledge of the circuit does not help. For example I do understand that there is a transformer in one of the diagrams with 1 input and three different outputs at different voltages, but that's about it. It does not help either that there are vacuum tubes involved. I hope to understand this circuit and make use of digital ICs to achieve the same function some day (maybe a few months?)
Please help me. I don't need babysitting to be told the meaning of the entire diagram, you can simply point me to topics I should read that would help me make the most of this drawing. I can send pictures of the actual setup if so required.
If possible please do not share it outside of your technical circle as this is somewhat confidential. (I do understand the irony of posting this on a public forum).
Link to drawings:
https://drive.google.com/drive/folders/1-CkS7K524fzfrg-B71uBU9zicqudNMb2?usp=sharing
Thank you in advance
 

MaxHeadRoom

Joined Jul 18, 2013
20,927
Cannot really see the actual details in the schematics, they may need a little improvement in drawing technique.
Also, if this is a complete machine, I would expect to see a combination of general machine wiring Schematic and the individual module schematics drawn separately.
To see them in the full context would help.
Max.
 

shortbus

Joined Sep 30, 2009
7,768
I hope to understand this circuit and make use of digital ICs to achieve the same function some day (maybe a few months?)
Not making fun, but that line made me laugh. I've been trying to come up with a circuit for sinker EDM for more years than I care to admit. I ran sinker EDM machines for many years and wanted one for myself so started to build one. Much harder than expected.

That saaid if this is for a company and to make money I'd look at one of these - https://baxedm.com/product/bx17-arc-generator/ But you will still need to come up with a way to control the ram, I'm assuming if the machine still has vacuum tubes in the power supply it is using a hydraulic ram with "piddle valve" control. Can I ask what make the machine is? Elox? that is what our vacuum tube machines were.
 

Thread Starter

ads295

Joined Jul 9, 2020
2
Cannot really see the actual details in the schematics, they may need a little improvement in drawing technique.
Also, if this is a complete machine, I would expect to see a combination of general machine wiring Schematic and the individual module schematics drawn separately.
To see them in the full context would help.
Max.
Uh okay. There are a few other wiring diagrams as well. The gentleman currently running the show, gave me these two saying they were the most important and that the motors M1, M2, M3 require the most attention. I'll upload the rest tomorrow morning when I have them...


Not making fun, but that line made me laugh. I've been trying to come up with a circuit for sinker EDM for more years than I care to admit. I ran sinker EDM machines for many years and wanted one for myself so started to build one. Much harder than expected.

That saaid if this is for a company and to make money I'd look at one of these - https://baxedm.com/product/bx17-arc-generator/ But you will still need to come up with a way to control the ram, I'm assuming if the machine still has vacuum tubes in the power supply it is using a hydraulic ram with "piddle valve" control. Can I ask what make the machine is? Elox? that is what our vacuum tube machines were.
Ouch. Okay. My only goal was to somehow get off all this 1960s technology and use modern control and power supply. I'm not looking to build one from scratch, but to modify this one. Also, die sinker EDM is different from this in the sense you're just drilling a tiny hole for maybe 3-4mm max and that's it. We don't cut material. There is no "table". A regular sized desk could hold 5 of the sparking units themselves (excluding the power supply and control circuit). And the hole sizes are really small, we go as low as 0.18mm. I'm actually trying to find die sinker EDMs that use wires this small (we use tungsten wire) but all of them stop at 0.3mm. Hence the idea of upgrading this one.

Company I don't know but it's Czech.
 

MaxHeadRoom

Joined Jul 18, 2013
20,927
If it is a EDM then the only way it works is on the erosion principle, there is no 'drilling' per-se.
So generally as far as I know, there is either die sinker or wire EDM.
If wishing to replace the power supplies, then it should be possible with the right KVa transformers and rectifying devices, the controller has to be a type of servo control of some sort.
Max.
 

Reloadron

Joined Jan 15, 2015
5,510
What I see is an early EDM (Electron Discharge Machine) a process developed by the Russians during the 50s. I worked with one once of early 60s vintage and like yours it used vacuum tubes. Upgraded it using another machines parts to solid state. I would start at the beginning checking the power supply voltages. The motors from what I recall are for the X, Y and X axis and are normally DC so bi directional by reversing polarity. Two move the table (X and Y) and the third is the Z axis. Machines I worked with used an oil submerged arc (oil bath submerged arc). The idea is the arc voltage is set and as material is removed and the gap increases the arc voltage control works to maintain the set voltage so the head motor (Z Axis) drives down into the work piece. By your description yours is a very small unit. I also noticed in your drawings the tube part numbers are European rather than what I am used to, for example an EZ81 is a 6CA4 to me.

I understand tiny hole as we used the one we had for removing broken for example drill bits when a CNC machine would snap a bit off in what was at that stage a very expensive part.

Keep in mind that when you replace old rectifier tubes with solid state diodes you can see a 10% to 20% increase in output voltage so make sure any capacitors used for filtering are in good shape. Also looking at the power supply schematics the resistors used are likely high wattage power resistors.

I would look at the whole picture and think about what you want to upgrade one small piece at a time.

Ron
 

MaxHeadRoom

Joined Jul 18, 2013
20,927
I understand tiny hole as we used the one we had for removing broken for example drill bits when a CNC machine would snap a bit off in what was at that stage a very expensive part.
Most companies do not want to tie up an expensive EDM machine for that so there are Tap-Busters out there for doing exactly this, they are a little cruder than their EDM cousin, they work on very low level, high current AC voltage. ;)
They didn't use any servo action as in the EDM system.
Max.
 

Reloadron

Joined Jan 15, 2015
5,510
Most companies do not want to tie up an expensive EDM machine for that so there are Tap-Busters out there for doing exactly this, they are a little cruder than their EDM cousin, they work on very low level, high current AC voltage. ;)
They didn't use any servo action as in the EDM system.
Max.
Beats me as my only involvement was with the old EDM machine. Guessing that adventure was maybe 20 years ago. The original design had a big rack of Thyratron tubes. We could nail the failing ones by the color change of the glow when the tubes fired. I am sure by today what I worked with has been long replaced. I know my old department has added millions of dollars in new stuff just over the last seven yours since I retired. No clue what has gone on in the machine and weld areas.

I know today some of the fine porting jobs I have seen on gun barrels are EDM.

Looking at those old drawings told me the thread starter has his work cut out for them. Going solid state eliminates the High Voltage and need for high voltage filter capacitors. No tubes which are getting hard to come by, even from Russia.

Ron
 

MaxHeadRoom

Joined Jul 18, 2013
20,927
The original design had a big rack of Thyratron tubes. We could nail the failing ones by the color change of the glow when the tubes fired.
Going solid state eliminates the High Voltage and need for high voltage filter capacitors. No tubes which are getting hard to come by, even from Russia.
Ron
Hear ya.
I worked with Thyratron tubes, these were used to fire the larger Ignitron version, (old/used ones were a lucrative source of mercury)!
The later equipment used a SCR/Triac style of devices.
Incidentally the generating stations here that use DC H.V. transmission, originally switched the H.V. power with Ignitrons, now all Solid state. :cool:
Max.
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