I’ve decided to start on a MPCNC. One thing I’d really like to eventually do is control a plasma torch (or even oxy). My question is how long will the plastic parts/belts/etc last with molten slag flying around with a plasma cutter?
Good question. Most of the slag should be dropping below all the plastic parts, so only piercing cuts will shoot crap near the plastic parts. I don’t think anyone has run one long enough yet to say.
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I’ve run my plasma cutter on my LR for a few months now with no problems due to heat/melting, even with a printed torch holder. If the pierce is done correctly (about 0.150" above the material for thin sheets), then you shouldn’t get too much molten blowback. This is done to keep the nozzle free of slag while cutting.
Only issue is if you don’t have a water table then metal powder will get everywhere. Just need to keep it clean so it doesn’t interfere with the conduit. Also, keep it clear of the electronics. It can build up and short out connections.
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Thanks for the answer, I’m glad to hear that!
Since I’ve got your ear can I ask what measures you took to shield your motors/electronics from the plasma’s interference on your low rider? What torch are you using?
First start off with either a pilot arc or blowback style plasma cutter. Stay far away from the cheaper high frequency start. Dui has shown in his Mpcnc made in China the lengths he had to go through with copper foil to shield everything.
I used 22/4 shielded alarm wire for all of my steppers and endstops. If needed a ground rod can be driven into the ground and the shielding drained to that. I luckily haven’t had any noise issues outside of my wifi router going down when the plasma cutter is on. All machine motion has been uninterrupted.
I, and a few others on here am using the Lotos LTP5000D pilot arc cutter.
Here’s my build: https://www.v1engineering.com/forum/topic/somd-lowrider-plasma-cnc/
It shouldn’t be affected too much by heat, most of it will be directed downwards anyway.
What can really be a struggle is the EMF, depending on what plasma cutter you plan on using this might be very nasty. Grounding might be a nightware so I’d suggest you to check on good plasma cutters, look for threads of people using cutters who don’t need too much shielding (ie, not mine).
You might also want to use a water table to limit warping, especially for thin sheet cutting.
What I don’t know is how much IR output those cutters are outputting. This might cook your plastics on the long run, I’m pretty sure it would take years, but that might be something to look at.
Last point, plasma cutting is dirty, you’ll end up with molten metals and slag flying everywhere so you’ll have to protect everything, especially the electronics, and clean your tubes as often as you can.
Good luck with plasma, it’s not easy. But once it works it’s awesome.
What are you guys using for your CAM software for the plasma table? We need curved lead-in/lead-out and pierce operations, right? Any other plasma specific operations? (excluding THC at the moment)
I had a brief discussion with the guys at Estlcam and the opinion is that it’s not very well suited to plasma. But after taking a brief look at the gcode generated by Estlcam I’m thinking it would be fairly straightforward to write a script to automatically edit estlcam’s gcode output to add piercing and lead-in/lead-out, right? Just need to refresh my vector math skills… But before I do that what are the other options?