DIY EDM Wirecut + Sinker

[franzschluter]

Hello guys. I am new to this forum and would like to discuss in detail regarding homemade edm sinkers and wire-edm.

History:
In my 3 year experience of building sinkers I am now planning to go into the next step which is CNC Sinkers (Orbital Axis) and EDM wirecutters.

Machines I built previously were all analog meaning no computers involved and ran on primitive analog circuits. I built 3 machines which were.

EDM Machine #1. RC sinkers directly from Ben Flemings book which was an RC type. It did its job but didn't work nicely with copper electrodes due to high wear outs.

EDM Machine #2. From the disadvantages of the RC machine I built my very own pulse EDM. It runs on 380V 3phase and electrode open voltage is 105.4VDC and can let 120 Amperes flow. It is capable of generating 100Hz to 20kHZ. Some range of frequencies produces DC ARCing depending also on "ON" and "Off" times. This was a big DIY project and I used an OLD Broken AGIE sinker as its structure.

EDM Machine #3. Concluding that Pulse and RC has its own advantages. I combined the two setups into 1 machine that allows RC and Pulse spark generation. Pulse for roughing and RC for finishing jobs. The servo module is also now more complex than the previous versions. Not wanting anything to do with PLCs and PCs I designed a motherboard (LOGIC CARD) that consists of CMOS LOGIC gates for controlling the entire machines process. A software called LOGIC FRIDAY assisted me in creating the complex board. All limit switches and buttons buttons operates on 12V.

Now to discuss my plans on future setups I need advice for a CNC WIRE EDM. I currently have the structure ready. I received an OLD AGIECUT Wirecutter that has been infested literally by RATS. Meaning its connections and circuits were unusable and eaten away. Only structure what I will use is its Table and Wireguides which are still in acceptable conditions.

The IDEA:
There are 4 stepper motors in the table. It has X and Y axis 400x400mm travel and two other axis U and V for producing tapper (Movement of head only). The tapper function seems a bit complex at first to me so I will leave this out. Going back to XY stepper motors I have disassembled them and am disappointed that no make or rating is written on it. There are 9 pins and I believe it is better to replace them with a CNC stepper motor + Driver board kit. What I want is the XY motors to be controlled via MACH3 software. I will make a limit switch of circuit that detects the voltage gap via probably a voltage divider. This send signal to MACH3 and will pause the cycle when triggered. Another voltage divider will be also designed to give another signal telling MACH3 to reverse run to go a few steps back till the gap voltage is finally reached the two voltage divider will have only 1 potentiometer and will be mechanically ganged. If open voltage is open it will advance starting the RUN cycle. Wire tension,flushing,Wire feed controls will be made independent from the program (Since I am a beginner in CNC).

Problems:

CHOOSING STEPPER MOTOR.
I am unsure what type of stepper motor to purchase for this job. The stepper motor that was in the machine has the following dimensions:

Body Length: 92.5mm
Body Radius (Round stepper motor): 83.8mm
Shaft Diameter: 9.5mm
Shaft Length: 32.6mm
Wirings have a common and is integrated inside (I think they call this unipolar). It has a total of 8 coils. Therefore it has 9 pins.

By looking at this perhaps someone here can recommend me what stepper motor is best to use for this application. I would not mind the machine axis to be really slow as long as it can be as accurate as possible. I have also included some pictures of the stepper motor that was mounted on it including the diagram how it was connected.

Software issues and problems:
MACH3 isn't designed for DIY CNC Wirecutters.
STOP OEM CODE:
I intend to use the STOP function as a trigger when the voltage gap is reached. But reading the manual it says that stepper motor may loose steps in this process. What will the real issues be here? I intend a really slow feed rate and I think it is unlikely to loose steps since the process is very slow.

Of course I would love also to use the FEED HOLD function instead. But I see problems that in simulation mode it is not braking fast enough for me. I do not know how to adjust this? We have to assume if it doesn't stop fast enough that it will hit the workpiece and the wire may eventually break.
Perhaps someone can advice me on this.



START OEM CODE:
I will use this to resume feeding the electrode to the workpiece when an OPEN Voltage is detected. When the voltage divider gives no signal it will simply trigger the START OEM CODE. I see also problems in this. As in the initial setup the OPEN VOLTAGE will really trigger the start button initially even when doing nothing. Meaning it would be impossible to work decently.


REVERSE RUN OEM CODE:
This is the key to how to make the wire retract when the gap is too close to the Voltage gap. Problems here include that in MACH3 it requires to be in the
"FEED HOLD" and then press REVERSE RUN. Notice also that this problem is in conjunction with the START BUTTON! Meaning by simply switching ON the machine it will already start because START CYCLE is triggered!

Possible solutions:
Perhaps someone is more familiar with MACH3 than me and can guide or perhaps give me a new light or hope. I have been only trying to use a DEMO version being unsure to purchase it or not. Though the Reverse/Feedhold/Start Cycle seems very useful to me.

Other possibilities is by programming a script or perhaps a macro for this? I have to admit that I have no talent in programming and perhaps this option might be no good for me unless someone could point me out.

Another possibility is perhaps there are other PC CNC controller software that has this function REVERSE RUN, PAUSE, RUN CYCLE.

Another idea which someone has already told me is that Plasma cutters have a function called torch height controller. I have no idea how this works and am also finding trouble where to get materials to read about this. And how it really works.

Any help is really appreciated as I am currently stuck in this phase.

Best of regards
Franz

[punish3r]

Software issues and problems: MACH3 isn't designed for DIY CNC Wirecutters.

Another possibility is perhaps there are other PC CNC controller software that has this function REVERSE RUN, PAUSE, RUN CYCLE.

True enough. If you're not too invested in Mach3 you should try out EMC2. I know for a fact that 6-axis wire EDM's have been successfully built with EMC2 as the controller.

Secondarily, the HAL in EMC2 should allow you to bypass the issues you're having with Mach3 cycles and 'buttons'.

The learning curve for EMC2 is a bit steeper than with Mach3. A familiarity with Linux, ladder logic/PLC programming and hardware interfacing is helpful if not necessary. Considering the content of your post, you shouldn't have a problem. There are lots of resources available on the Internet covering all aspects of EMC2 and Linux in general.

A link to the EMC2 project: LinuxCNC.Org

[franzschluter]

Originally Posted by punish3r True enough. If you're not too invested in Mach3 you should try out EMC2. I know for a fact that 6-axis wire EDM's have been successfully built with EMC2 as the controller. Secondarily, the HAL in EMC2 should allow you to bypass the issues you're having with Mach3 cycles and 'buttons'. The learning curve for EMC2 is a bit steeper than with Mach3. A familiarity with Linux, ladder logic/PLC programming and hardware interfacing is helpful if not necessary. Considering the content of your post, you shouldn't have a problem. There are lots of resources available on the Internet covering all aspects of EMC2 and Linux in general. A link to the EMC2 project: LinuxCNC.Org

Thanks I will try checking it out. If EMC2 can integrate the reverse run function of MACH3 then I will definitely dwell more into this. Only reason I preferred MACH3 was it's reverse run code which is essential in EDM process for retracting or backing up electrode/wire. If this can be implemented then DIY XYZ EDM router/ XY UV Wire EDM would be no longer a dream.

I have a basic program using MCU and stepper motor to drive my RAM up and down. This was my final sinker project that only had a Z-axis. You can input depth in terms of steps and that was it. Retracting and advance was done by subtracting and adding number of steps including delay in C++. But doing the same thing on wire edm or xyz edm will be much much more difficult to implement. Specially when driving two or three axis at the same time.


And Yes I have familiarity with coding a little in linux but not well versed. I am an electronics/mechanics person but not so well versed in programming.
Recently I have bought a complete CNC router set on ebay from BZT hoping to learn further about CNC operation. Though my goal is to build a DIY wirecutter, I will use the router to serve my experiments in mastering CNC software and hopefully be able to develop a simple DIY EDM wirecutter.

[mdynac]

yes EMC2 will do a basic edm function, it is called "adaptive feedrate"
this varies the feedrate in accordance to a variable DC voltage.
i'm not sure if the emc guys did any more with it since it was developed at the CNC fest in southern illinois several years ago.
i used a MotencLite pc card. it has + - 5 vdc analog inputs on it which a/d's it and it is ready for emc2 use....

i sucessfully converted a Charmilles/Andrew EF-330 Wire EDM from a DEC pdp8\a control
to a modern pc using EMC2

good luck

[franzschluter]

I have read and researched about using EMC2. And I am still puzzled. Is it possible to use open loop when using these functions?

Or is PID a MUST? Thanks. If its PID using MoteNCLITE how difficult is it to use? Does it come with a manual? So far I only know how to use and configure open loop systems. I have never tried using closed loop such as usage of encoders and scales. I would prefer to use only an open loop system and perhaps would consider the feedback as analog.

[gombault]

Hi Franzschluter,
I am now putting a new controller on to my old Chinese Wire EDM machine. I found a company in china that would sell me a new complete controller with all the software for $1500. The stepper motors used on my machine is known as three phase stepper motors. These motors are used on most of the Chinese machines, and they work for days without generating any heat. I had this machine for 15 years and know its workings; I also built two machines using EMC. I myself would not try using EMC or MACH3 on a Wire EDM machine.

[franzschluter]

Originally Posted by gombault Hi Franzschluter, I am now putting a new controller on to my old Chinese Wire EDM machine. I found a company in china that would sell me a new complete controller with all the software for $1500. The stepper motors used on my machine is known as three phase stepper motors. These motors are used on most of the Chinese machines, and they work for days without generating any heat. I had this machine for 15 years and know its workings; I also built two machines using EMC. I myself would not try using EMC or MACH3 on a Wire EDM machine.

Hi could you give me the name of the chinese company or perhaps their contact info through pm here. I'd like to get into contact with them.

[gombault]

Hi,
The e-mail address is info@wangping-tech.com
Address it to Randy Lau. Tell him Marcel referred you and you are looking for the same controller he is supplying me. I would suggest you get the three phase stepper motors from him as well, as the stepper drives inside the controller are for those motors.

[kulk_sd]

do you intend to publish the scheme, you have worked with, like circuits & other details.

[mescotc]

R u happy with the quality ?

[kulk_sd]

Originally Posted by mescotc R u happy with the quality ?

Yes & let me have more photographs of the work, so that I can completely view the work.