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Here’s the build log for my Lowrider CNC Plasma/Router combo.
Specs
Update: There is now a 48"x48"x3" water pan installed while plasma cutting to keep the smoke down. After a few tries of sealing leaks, it is now operational and much much better than cutting on open slats. The garage no longer hazes up with conductive metal dust which can damage other electronics, and I am no longer inhaling all of it! I would highly suggest adding a water table if you are doing any significant amount of cutting.
Working area is 4’x5’ with a footprint of about 5’x6’. The 4’ (about 50" actually) was the critical dimension because I did not want to have to rip stock down to get it to fit on the table. I settled with 5’ on the length because I value the garage space more than the few times I imagine I will be cutting an entire sheet. Since the table supports 6’ of length, I can easily cut a full sheet by splitting the jobs and shifting the stock in between.
Hardware
Update: I am now using Mesa electronics hardware (5i25 & 7i76 combo, with the THCAD-300 THC) with a Dell Optiplex 960 PC running LinuxCNC. I learned early on that you just can’t get reliable cuts without a torch height controller, which GRBL does not support. I switched over to LinuxCNC so I could use a proper plasma setup, and I couldn’t be happier. There are plenty of inputs and outputs on the breakout board (32 in, 16 out) which can interface all of my limit switches, torch/router on relays and future user MDI buttons. The board also has 5 dedicated stepgens, so I can run each stepper motor off of its own driver. The drivers that I am using are TB6600. This allows me to move up to NEMA 23s if I find I want a little more speed for rapids.
I purchased the Hypertherm 45XP unit with the machine torch because I was losing my patience with the Lotos machine. While capable of cutting the 14 ga, I would still run into issues because the arc voltage coming off the unit (which is measured by the THC) was quite dirty. This led to crashes and material wasted. After switching to the 45XP I am able to cut almost twice as fast (250ipm vs 140ipm in 16ga) and the cut quality is miles ahead. No more edge angularity on parts, and much less dross on the back side. This wasn’t a necessary upgrade, but I am glad that I did it. Another thing, the Hypertherm doesn’t cause my WiFi to black out whenever it is turned on. This is convienient because I routinely ftp files between my home PC and the garage over the network, as well as listen to music via an Echo Dot.
OLD
I am using the standard RAMPS 1.4 stack with DRV8825 drivers and NEMA 17 steppers (84 oz-in I believe)
The plasma cutter I am using is the Lotos LTP5000D, 50A, pilot arc start with the standard torch and running off of 220V. For such a low cost cutter, it has surprised me with its cut quality, but I have much to learn yet about reducing dross and minimizing part cleanup. I have ran 22/4 shielded alarm wire for all of the steppers and grounded the shielding inside a metal junction box. So far, I have not seen any problems due to noise from the plasma cutter. However, I use a Netgear powerline adapter to get internet to the garage and rebroadcast it with a secondary router for wifi, and the plasma totally messes the signal up when the machine is turned on.
The focus of the machine is for plasma cutting thin (14 GA) sheets of steel, but easily switchable for routing with replacement of the slats for 2 sheets of 0.75" MDF. (Yes, I understand the potential hazards of mixing sawdust and hot bits of metal). I already have a 28"x28" MPCNC for most of that work, but always had been itching for something larger. The MPCNC will probably get resized in half for a better focus on rigidity.
Software/Firmware
Update: As stated earlier, I am running LinuxCNC on the Mesa electronics. LinuxCNC runs on a realtime kernel which means that there is no command buffer like Marlin and GRBL firmwares. This is convienient when jogging around as I can just use the arrow keys and whenever I’m at the position I’d like I stop pressing the button. No more worrying if the key was pressed too many times and its going to jog further than I wanted. This small feature is one of my favorite parts about the switch. LinuxCNC is used by a lot of industrial CNC companies. Tormach’s PathPilot interface is running LinuxCNC. Customizability is through the roof, as is the support of the userbase. The only drawback is that it does require more hardware (a full PC running Linux).
OLD
Flashed onto the Mega is GRBL 1.1f. I wanted something more geared towards CNC with better user interfaces than the LCD screen or other 3d printer oriented solutions. I have tried CNC.js via the Raspberry Pi 0W, and it worked until I turned the plasma cutter on and it takes out my wifi. I needed a solution that would not require networking, and I could control from the CNC. I am currently running bCNC on a Raspberry Pi 3 with a 7in touch LCD and it seems to satisfy all of my needs. It is fast and responsive (doesn’t require network connection to send commands which results in double jog movements or otherwise no response), and the GUI works well on the Pi3, whereas cnc.js would not. It also has a lot of great gcode editing tools and some limited CAM functionality which is welcomed.
To-Do
Tear it all down and paint everything
This has been a work in progress where I’ve been learning a lot about welding and metal working in general. Thanks to you Ryan for making this platform that we can take and create things with at such a reasonable cost, and most of all supporting it to a high level. I went all in on the MPCNC two years ago and have a MP3DP as well because I knew this community has a strong base and it’s a great place to hang out (or in my case, lurk).
Google album with more details, videos as I progress… https://photos.app.goo.gl/WywV1Q9XHMPcCAEk7
