Sodick wire EDM machine retrofit

Hi!
Thanks for the help
At this stage any info is very welcome.

I have made some progress since my last post. Basically I have everything working on my machine but I had no option but to ditch the original spark generator. The original one is very complex and I could not find enough info on it to even try and get it integrated with linuxcnc. The multi layer PCBs in it makes it impossible to try and trace the circuits so that was a no go as well.

I have built my own spark generator and I have made some test cuts in steel up to 30mm thick. Im now starting to understand the enormity of the task that I have took on....it is not simple at all.

If you are prepared to spend money, buy the BAXedm spark generator. I don't have first hand experience on it but that will solve a lot of problems if what is advertised is true.

I am now playing with the adaptive control that is supposed to control the spark gap by adjusting the feed rate based on the gap voltage. I have not spent enough time on this to be able to comment on it but I will try and post here some details and my findings in the future.

My spark generator is a simple high side MOSFET switch with adjustable current limiting resistors and also adjustable on and off times for the pulse. I don't have any feedback that is capable of adjusting pulse parameters (current, voltage, on and off times etc) automatically but some friends over here offered to help develop such a system.

In short. I have cut material, bit painfully slow and not yet useable at this point. I have a lot of development still to do.

I will keep you posted.

Henk

You should look into external offsets and reverse run, both are included on LinuxCNC 2.8 and master, they are very useful for EDM.
Combined they should provide for speed adjustment during cutting and back off when the voltage goes to 0, although most probably only external offsets will do all the magic needed. Add to that a THCAD10 from Mesa for measuring the voltage and sending it to LinuxCNC.
PlasmaC should be a good starting point for that.

I found the machining tables and Ive put it up on a host for you to download here, it might be useful if to get a grasp of how it was done OEM if nothing else :-
gallery.pipandphil.com/Vehicles/workshop...hiningConditions.pdf

Ive also added the manuals for the MK25 the MK21WT and a file called materials cross converting between JIS &AISI metals standards as referenced in the cutting tables book.
gallery.pipandphil.com/Vehicles/workshop/MK25Manual.pdf
gallery.pipandphil.com/Vehicles/workshop/MK21WTManual.pdf
gallery.pipandphil.com/Vehicles/workshop/material.pdf

I thought I had a repair manual with wiring schemas for a differetnt machine to mine, but when I offered it up a lot of circuits were similar, if I can find that again I'll post it here as that may still be of use to you. I have the servopack drive manuals if you have yaskawa servos fitted to your model also as I had to repair one of my axis as I got it as a broken machine also.

Also what I see as a slight issue is the original control was loaded with compensation settings for the ballscrews etc which are stored on floppy disk, or if you were really lucky (like me) also on a yellowed print out deep inside the machine cabinet. Without these the oem mapping of the screws etc will have to be redone of course.

Believe it or not, 3k is outside my budget for a part for this, I have less than 1000e in it in total (and its currently working condition). I'm just a hobbyist with big dreams. The converting it is a wish for now as I'm busy building a room to house a cinncinati sabre vmc after outgrowing a bridgeport interact

I'll have a dig round for the schematics/wiring manual, I'm sure I had one somewhere.

I have been researching building my own small WEDM and so have been collecting info.
You might want to look here (
www.cnc.info.pl/drutowka-dk7725-na-linuxcnc-t92321-20.html ) for hints on using LinuxCNC with WEDM. This particular retrofit does not use reverse run, they apparently don't find it necessary. The essense of their approach is to sense the voltage and stop moving when below a set threshold. It then 'sorts itself out' at least most of the time. Site is in Polish but easy enough to translate with the usual tools.
A few posts in there is a copy of the .hal file being used.

Also have a look through the LinuxCNC email list archives, I recall some detailed discussions about voltage / current profiles there a year or so ago.
sourceforge.net/p/emc/mailman/emc-users/

Here is another rather sucessfull retrofit with LinuxCNC:
www.cnc.info.pl/elektrodrazarka-drutowa-na-linuxcnc-t67931.html

And on youtube here:

He is also using the method of just stopping when there is a short, and continuing when it's fixed.

I like the convenience of the cooling only being trickled on like normal cooling like when milling. He's even using regular cooling fluid. Would it be possible to put this on as an attachment on a regular mill? It looks like that would be possible.