CHEAPEST CNC PLASMA - FIXED RFI!
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- Опубликовано: 3 апр 2023
- I solved the RFI problems that were crashing the Mach3 USB controller on my CNC plasma table. I also figured out how to make CamBam work with a non-pilot-arc plasma torch!
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I built a CNC plasma cutter using a cheap cut 50 pilot arc machine but it produces too much emi. I battled the emi issue for quite a while before addressing it on Open Builds forum. By the way open builds control is excellent software for controlling your CNC machine and it's free. They also have Open Builds Cam for converting your files to G-Code and it's also free. A moderator on Open Builds suggested I use a blowback torch plasma cutter rather than my high frequency pilot arc. He said I will find it much more economical to replace the HF plasma cutter than to jump through all the loops with shielding attempts.😮 I have to agree and plan on getting a blowback start plasma cutter. In all of my previous attempts the thing I discovered produced the most interference was the plasma cutter lead itself. It acts as a huge antenna. I was considering making a sleeve for it out of Faraday fabric but decided I would spend the money on a blowback cutter instead. Blowback cutters are generally used most often in environments where sensitive electronics exist. According to the open builds moderator high frequency start is 1970s technology. And while it still works it can be very frustrating in an environment using a cheap arduino-based boards that utilize USB connectivity - such as my MKS DLC 32 v 2.1 control board. I use Grbl.
The metal boxes were absolutely necessary and you are correct that the Capacitors shunting AC to ground is the best change.
Placing Ferrite cores clamped around wires are for reducing HF-VHF-UHF ~emissions~ (Mostly for passing FCC/EMI tests), and seldom have any affect at all on the signals within.
GREAT JOB ON THE GROUNDING TOO!
Thanks for the kind words!
@@JakevonSlatt how did you come up with the size of the cap to use for the filters? Were you able to see the noise on an oscope?
@@tommyhudson9858 I don't remember exactly where, but I found a blog post about a USB device that had interference issues in an industrial environment and 4700pf was the value they used.
Good job knocking down the interference!
Thanks!
Very helpful and clever solution thank you.
Glad it was helpful!
Thanks great video. I am building a CNC plasma cutter and I may have overkilled the strength and weight of it. I could probably attach a high-torque motor and use it as a mill.
Look into a "drag knife" for cutter cardboard, gasket material, vinyl, etc.
Nice work! I've used Cambam for several years and it defaults to inches for me. I'm wondering if there's something in preferences that you need to set to inches.
Thanks for the kind words!They’re a UK based company so it’s not surprising that “native” units are metric. I think there’s a default preference file that saves your preferred units but the plasma template and style files override that when you load them.
great!
Hi Jake thank you for bringing to my attention your video. I didn't understand perfectly what are you connecting the capacitors with, you say all the lines but i am not sure. is it like all the motors cables ?
Every stepper and limit switch wire on the gantry gets a 47pF cap to ground so only DC current gets back to the controller in the separate box.
@@JakevonSlatt Thank you for your answer! Pardon me for asking more about this i am just thinking of implementing it and want to be sure. So suppose i wanted to make the remedy(filter) for the first wire out of the four wires of the first motor, I would intercept its wire, add the capacitor and link its other end to the ground ?
When your work clamp is connected to your table or workpiece doesn't it essentially create a path between your plasma cutter and your electronics?
I like it 👌
I wanted to ask you a question about your CNC cutter. Do you have or plan to install the torch height controller? I already purchased it and many people claim that it will allow the head to keep a constant height above the metal if it is somewhat lighter gauge sheet metal.
I’m looking into a Arduino based open source torch height controller but I’m concerned it may not work well with my torch, I may upgrade it before I try.
This is a great video. Would you share the capacitor information? 4700F or 4700uF? 25v?? I have tried all the other things you did as well, just not the capacitors. Thanks for sharing this valuable information.
These are the caps I used, 4700pf ceramic disks: E-Projects - 4700pF 0.0047uF... www.amazon.com/dp/B00E6PGUI6
Thanks for your help. My old Shapeoko 3 is now a plasma cutting miracle. Amazing. Could not have done it without this video.@@JakevonSlatt
@@tomholgate4630 that’s awesome!
FYI re: caps for others. They’re designated as 472. Ceramic caps are rated in pico farads so the first two numbers are the value then the third number is how many zeroes. Eg: 4700
So with the filters you have built, one leg of the cap goes to the incoming line and the other leg goes to ground. Is that correct?
I have an old high Freq Pilot Everlast plasma that I ultimately quit using do to rfi and locking up my pc. This may fix that issue!
Correct!
Hi, apologies for my naivety but if you had used a pilot arc plasma in the first pace then would you still have had to do all the anti-interference work? Thanks
I think there would have been less work mitigating the interference. HF start plasma torches create a lot more RFI than pilot arc torches.
Yes. Experienced it first hand too. Even with these three stages of interference work, if the control box is closer than 2 feet away, I get some random stops. Each stage of work is needed but they are all simple.
I think what you're asking about is a low frequency start machine such as a blowback plasma cutter. They produce FAR less high frequency interference what are recommended for environments where sensitive electronics are located - such as CNC control boards. Pilot arc doesn't necessarily mean low frequency or low interference. I have a pilot arc machine and it emits a ton of electromagnetic interference. In fact so much that I plan on replacing it with a blowback start machine rather than fight the arduous process of shielding and isolation.
You couldn't just wrap your wires in aluminum foil?