The blacksmith's plasma table

Hi everyone,

I'm a blacksmith/metalworker with my own shop, and I'm in the process of building a CNC plasma table and I thought I would create a subject on this board to help me go through the electornic part which scares me a little.

I'd like to use LinuxCNC to run it with a Mesa7i96s and Mesa THCAD, and an old computer I have. I've found this subject which seems to be really helpfull (with a complete wiring diagram) : forum.v1e.com/t/lowrider2-plasma-build/13939/4

I'm a bit lost though because electronic is a bit complicated to me and would like some precision about how this thing works.

First I understand the needs for a floating head. I also understand that it can be build with a limit switch. I'm not sure though how it goes in the grand scheme of things. Do linuxCNC already knows how to use a floating head ? Is it as simple as telling LinuxCNC which pin of the Mesa 7I96s is connected to the limit switch of the floating head and teeling it the distance it has to go up after the switch is triggered, and then use Gcode to tell the plasma to probe the distance before each cut ?

Also I currently own a Stalhwerk cut 70 which I believe is HF. From my lecture on the subject a HF CNC plasma is really not a good idea. I'm ready to sell it and to buy another plasma CNC compatible (I'd like to have already pins on the plasma because I dont trust myself opening it and playing with voltage dividers etc, as I said I'm not confortable with electronics, even though I try to learn). Hypertherm is not really an option as of right now because of the price. I believe Stamos make a CNC compatible plasma cutter for a bit less than 700 euros.

Could someone confirm that I should wait to know which plasma I'll use before I buy the THCAD as I believe it depends on the arc voltage coming from the plasma (some already have a voltage divider, other not) ?

I'm really sorry if my questions sounds messy, I'm not a nativ english speaker and I'm a bit lost with the huge sum of inormations (sometimes which contradict themselves) I find on the internet. I would greatly appreciate any ressources you have which could help me in my project. Thank you very much for reading me. I plan on updating this subject as the building goes.

Some pictures of my 3D model and the start of the build (I'll replace the 3D printed part with aluminium one's once I've validated the build):



 

Thank you very much for your answer, I believe I need a relay for the torch on and off if I go with the stahlwerk ? (I actually would like to since it prevents me having to buy another one). Also, is it hard to wire the THC and the arcOk signals in the stalhwerk ? Do you happen to have a picture of the set-up ? I believe I can try to manually turn on the plasma close to the table when I've wired all the step mottor and limit switch and see if I have EMI problems right ?

Would you have an advice for the drivers ? I have two Nema 23 (3A) for the Y axis, a nema 17(1.5A) for the X axis and a nema 17 (0.5A) for the Z axis. I think I'm gonna buy the electronics soon so I can start to configure LinuxCNC and see if everything's ok movement wise before I start to dabble with the plasma and THC. I heard gecko's one are good but they're pretty expansiv.

Man you're precious. Thank you a lot for all these usefull informations. Just bought the Mesa 7I96S and the THCAD-10. Was a bit of a pain to find in europe but finally found it on eusurplus (funny how my google search always end up on one of your answer on another subject). I'm glad I can buy cheap drivers because the Mesa cost more than what I was expecting with taxes and shipping. I've read the plasmaC documentation. I'll take a picture of the inside of the plasma cutter when I have time. I'm still hesitating if I buy the Stamos or try to fiddle with the Stahlwerk I already have. I would learn more thing using the stahlwerk, but i'm afraid to break something, or worse, injure myself with these high voltages.

Thank you again, I'm a bit lost in this project and it's reassuring having someone to help a bit ! Yet, I'm exited. This plasma table will be really usefull in my work (and will save me countless hours with the grinder), and understanding how to do CNC stuff by myself is very rewarding.

Hi man.
I have received the Mesa cards, ordered the driver and a 36V alimentation. Do you think I can use a basic 5v alimentation which came with an Arduino to power the Mesa 7i96S ? Or use something like a USB phone charger or should I buy a better alimentation ?
Also I'm not sure what should I buy to wire all the electronic, between the cards and the driver etc. Does simple electronic wire I have laying around can do the trick ? I believe there isn't much power exept in the motor circuit after the drivers.
If you happen to know the english name of those nice connectics (with the 4 pins for the motor and such) so I can order some that would be greatly appreciated. I'm gonna buy good shielded cable for the motors and the end-switches.

On another note I think I'm gonna use the Stamos. I have someone willing to buy my Stalhwerk and it reassure me a bit to not have to fiddle with the plasma on top of wiring all the cards and the driver. And It eliminates a big source of EMI.

I have pretty much all the different elements exept the wiring cables and the plasma and it cost me around 850e, almost half of it being the Mesa cards (withtaxes and shipping cost) so I really hope I'm not gonna fry it like a dumbass.

Grab a 5 volt DIN mount power supply from Meanwell or similar. I have seen many issues using usb/phone chargers

One gave me a big electrical shelf, all metal, with grounding wire and big coper bridge. There is plenty enough space to put both the electronic and the PC inside, I would drill hole for aviators connection to the motors and plasma cutter so the shelf can be moved independantly from the plasma table. Do you think it's a bad idea to have both (PC and electronic) in the same place ? Do you think it would be usefull to try to shield the electronic from the motor alimentation ?

I'm almost done with the mechanical part of the build, have received the drivers and the motor alimentation. Still lacking the 5v DIN alimentation and the limit switches. Hope I can soon start to wire everything and try the XYZ movement.