The plasma table, will have thc, and/or floating head. I’ve been tinkering with marlin and 3d printers for about 8 years, and I also converted a milling machine with mach4.
I want to use this plasma table as a way to learn grbl and Arduino, as I really know very little about that.
I’m having a hard time finding info on a start to finish project, with clear instruction, which makes sense as it seems most of this is learn as you go, as such write ups are written over time.
I played with open builds cad and cam and was easily in an hour, able to load a post in fusion, and simulate it in open builds, and for me that is very impressive.
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Hello there. Welcome to the forum. You’ve got quite a wall of text there. It might be easier to respond if you single out some specific questions?
Yeah I always start typing, then all the sudden it’s a novel. I edited the post.
1, what hardware is recommended for a plasma?
2 is there any write up’s start to finish of a plasma running grbl and some sort of thc or floating head.(ones I’ve found are only parts, and I’m not familiar enough to know what works together).
3 I would prefer a closed loop system, but don’t need to, but would like to run external drivers so I can use a nema34 motor.
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Linuxcnc was my original plan, with a Mesa 7i96s and thcad-2. But I really want to learn grbl, and more about arduino, as I think it would be really useful for future projects.
I have also read and watched most of Doug Joseph videos and his write up. He is very detailed and start to finish, but it’s Linux based, and I just don’t care to learn another limited-ish software, mach4 was hard enough, and has pretty limited uses, in terms of cost(hardware and software) and what it’s made for. Even now I have problems with mach4 that I can’t get resolved due to hardware limitations. IE: backlash comp, it’s worthless for the z axis, even worse than no compensation at all in some cases, though that wouldn’t really matter on a plasma cutter.
There is a lot going on with all this, and a lot of work in the LinuxCNC approach is to your advantage. The GUI called QTPlasmaC is nice. Eschewing all that will be like reinventing the wheel. Some of my videos show the cool features for resuming after a failed cut etc. I’m glad I went with the LinuxCNC approach.
Doug is in the house! That’s awesome! I watched your video yesterday with the resume cut. I also just edited my original post down. If I do go with Linux, I’ll be copying your electronics build. Thanks for all you’ve added to this community. If grbl isn’t up for the task, maybe someone can chime in about why that is. Or maybe I switch to Linux on both the mill and plasma, as it’s more customize able and can be made to have a useful backlash compenation using glass scales with the steppers encoders, I really don’t like mach4.
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You have given yourself the best advice here. I get wanting to learn grbl but plasma isn’t the correct approach. We run FluidNC on the Jackpot which is a version of GRBL. So if you are stuck on wanting GRBL then maybe build a LR3 for a router. If you are wanting a plasma table then @DougJoseph has the best build you can follow. But read all the way through before you start ordering parts LOL. Some changes and things he learned along the way will help you before you start. All his videos are great too!
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Yeah you’re probably right, I’m the type to step over a dollar to pick up a penny, or if it ain’t broke fix it til it is, or buy twice, have bonus parts. Made that last one up, makes sense to me, haha. I went down the grbl rabbit hole though, and it seems they’ve come a long way in just the last month or two, but a lot of the people end up switching to myplasm, which is limited to their myplasm software, which I don’t really like, I like to customize, and I think Linuxcnc with y’all’s recommendation is the way to go. So mesa and thcad-2 it is.
I noticed many people use 2 thcad boards, one for thc and one for ohmic/floating head, I don’t recall Joseph doing this, how do you run a touch off @DougJoseph ?
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I use a set up that has a floating-Z with an end stop switch for my touch off. So this means I have only the main MESA board which controls the stepper drivers, and the one MESA THCAD board.
Arduino is super useful. You honestly won’t be learning much using grbl though. Almost no one edits grbl, so you would just be using it. As others have said, it isn’t the best for plasma.
I would decouple this awesome plasma cutter that costs $$$$ with the desire to learn arduino. You can buy an arduino for <$10 and follow some tutorials. Wire it up to a drv8825 and a nema17 and spin a gear. It won’t be useful beyond learning, but when you know the possibilities, you can find a useful project. Addressable LEDs are another project that is easier than it looks, and end up halfway useful.
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Yeah I am going to heed your advice and go with the mesa 7i76s and thcad2, which Peter recommended. I replied to an email confirming that is the right thcad board considering I don’t have a built in divider, but I am thinking maybe you can get a better reading using that board and a divider or resistor, vs using the 300 board.
@DougJoseph With your floating z, which I will also have, did you just run your limit switch to an input on the mesa control board? any chance you have a schematic floating around?
Edit, just found a schematic you posted, I thought I had seen one when originally read through your build, took me a while to find it again. Thanks for doing that by the way, your whole build is a real time saver and takes the guess work out of a lot of it.
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I pretty sure If you go thought the thread I posted earlier he has everything you are looking for in there. It is an extremely detailed build thread
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Yeah I just found it, I knew I had seen it before.
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You found it before I got a chance to reply. Sorry for the delay.
I ordered my mesa boards!
Does anyone here know about powering steppers of different voltages? Im trying to keep my gantry as light as possible, so Im running a small nema23 for Z, and a small nema34 for X and a large nema34 for Y. My mill has all the same steppers and I went with a 1000W 70v toroidal transformer, but to keep costs down and because I will need significantly less power for the plasma table, I’m looking at the switching power supplies.
question is, do need separate PSU’s for each stepper? I guess the 2 nema34s could use the same 60ish volt PSU, but then I need something smaller for Z, or some way to step the voltage down from the X/Y PSU. Any ideas on the cheapest most efficient way to do this?
the 2 nema34’s can handle up to 80V and 8amps, I plan on a 60V 600+w PSU for it, but the nema23 can only take up to 50V and says 3amps, but the amperage changes based on voltage right?
I don’t know if it will help, but one of the videos in my plasma build playlist shows my control box power supply wiring in detail.
I just watched your video again, I’m just trying to find a way to get the proper voltage to the two different size steppers. What size steppers are you running that only need 24V? I mean any stepper will run, but you’re giving up a lot of torque.
All my steppers are NEMA 17. Seriously, these are overkill for a plasma rig. Even the LowRider plans for router based builds, also use / call for NEMA 17. For plasma, anything larger than that will be overkill on top of overkill.
My floating Z torch holder has magnetic breakaway, so that if the torch tip is going to collide with something, it will break away from the machine before it damages the torch tip. NEMA 17’s, even if only running on 12V power, is enough torque for router based cutting (that’s what is on my router based LowRider) and it is also enough torque to potentially damage a torch tip on plasma.
That’s good to know, I just based my sizing on what I had seen others do, the only reason I am going big on my X/Y is because I am using leadscrews, (because I already had them) and being a 6 foot screw, spinning very fast, I think it will need the torque to start and stop them, I don’t think it would have any problem moving anything, but because the torque curve of steppers is so steep, the faster they spin, the weaker they are, and I have to spin them quite fast, I worry they won’t have any torque left to stop. But it sounds like maybe I could just run a 48V PSU and power all 3 from it. Nema 23’s would be lighter though if I could get away with that size.