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Standalone Torch Height Controller for CNC Plasma Cutting

Discussion in 'Laser Cutters' started by Retsaj, Oct 7, 2020.

  1. Retsaj

    Retsaj New
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    Retsaj published a new build:

    Read more about this build...
     
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  2. Mark Carew

    Mark Carew OpenBuilds Team
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    Wow Jeramiah great share!:thumbsup: easy build and the bonus is the super cool breakaway torch holder!
    btw what plasma did you settle on for your table and pros and cons with it you could share? Thanks man
     
  3. sharmstr

    sharmstr OpenBuilds Team
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    This is AWESOME! I was just yesterday deciding weather I wanted to build a plasma table using the Lead machine or buy the Crossfire Pro. Was leaning towards the crossfire because of the lack of THC with the lead/blackbox setup. Thank you for posting.
     
  4. Retsaj

    Retsaj New
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    Thanks Mark! I hope someone finds it useful. For the table, I choose to go with an Everlast PowerPlasma 102i CNC pkg (~1 Phase 240V) this is the highest end of their PowerPlasma line but any of the PowerPlasmas are a good option in my opinion.

    PROs
    • CNC Run mode
    • Machine Torch option available
    • Pilot Arc NOT high freq starts. (much better for sensitive electronics)
    • Compressed Airline PSI Monitoring
    • CNC Port
    • 50:1 / 16:1 Arc voltage right off the machine no extra circuits to add.
    • Smooth Arc
    • Auto-restart lost arc mode
    CONs
    • Documentation could be a lot better
    • Needs 240v line
    • The loud fan that runs full blast when the machine is powered
    Here is their feature breakdown: https://www.everlastgenerators.com/...rs/files/c401e855e307d3651aaab628a190b4dd.pdf
     
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  5. Mark Carew

    Mark Carew OpenBuilds Team
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    Great break down thank you!
     
  6. mytechno3d

    mytechno3d Veteran
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    Really good job ,
    I will build one to try it on my diy plasma table..
    Thanks for sharing .
     
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  7. phil from seattle

    phil from seattle Journeyman
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    Interesting build. I have a few questions.

    Is there a sensor that detects torch break-away? So you can turn off the plasma automatically.
    Is there any isolation between the torch and the electronics?

    A suggestion, get a screw terminal Arduino shield and use that rather than friction fit connections in the arduino sockets. Eventually, those pins will work loose.
     
  8. Retsaj

    Retsaj New
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    No sensor sadly, I just stop my machine manually but a sensor is on my list of upgrades.

    Not really sure what you mean by isolate... But raw arc voltage never reaches my electrics only a 50:1 (0-4volts) do... This is a built in feature of my Everlast PowerPlasma 102i cutter.

    Cheaper plasma cutters that use high frequency starts should be avoided do the electronic noise problems.

    Good idea about the screw terminal shield I think I'll incorporate one myself... But for this build I wanted to keep the parts list as cheap as possible.

    Cheers
     
  9. phil from seattle

    phil from seattle Journeyman
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    Lots of electrical spikes can happen in a plasma. I wouldn't rely on just a resistive divider to protect my electronics or me. At the least, I would use a TVS but true galvanic isolation is pretty much standard in professional machines. Probably $5 worth of parts.
     
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  10. Retsaj

    Retsaj New
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    yea, my plasma cutter seems to output a clean signal. I think it has built in isolation but not sure... Ran the machine a few times with the scope on the output and it never got over 5v out when plasma cutting... I know this my situation and not all plasma cutters are alike so YES I COMPLETELY AGREE with you about the need for isolation. When I add the to the design in the future I'll post an update. if you beat me to it please share!

    Cheers!
     
  11. phil from seattle

    phil from seattle Journeyman
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    Glad to hear it. Would hate to hear your project took a hit! You might want to take a look at grblHAL. There is some THC work going there for a plasma CNC.
     
  12. mytechno3d

    mytechno3d Veteran
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    Hello , i just finished mine , but i have a little problem with it.
    Arc value is read correctly and display on the screen .
    So i think that serial connection is working correclty but all defaut value are set to zero and can not be changed ( like PID , delay , step/mm ...)
    It's look like an eeprom problem , did you see that before ?
    Maybe problem come from the nextion screen , reference is the same but there is some difference between yours and mine . ( RX and TX inverted , and some other little difference )
    Any help will be greatly appreciated .



    Thank's for your work.
    Michael

    Edit : After few hours of research. It still dont work , but i have some clues.
    I have a read ans write problem with thé eeprom (write out of limit) , i Also discover that Arduino does not receive the.trigger event.from the nextion screen.
    My next step : i will rewrite your code line by Line until i find where the
    problem come from
     
    #12 mytechno3d, Oct 26, 2020
    Last edited: Oct 27, 2020
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  13. HJackson02

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    Hi, did you have any luck fixing the THC as I have the same problem.
     
  14. HJackson02

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    Hi, do any of you know what is happening with my plasma voltage and how I can fix it. And I have got the same problem as another one of you do you know to to fix that as well. Everything Is wired up the same as the picture except I haven’t got a electrolytic capacitor will that make much difference. Thanks Harry
     

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  15. mytechno3d

    mytechno3d Veteran
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    Hello
    I'm working on it and make some progress.
    I think it will work soon.
    First problem : Eeprom address , some parameters need to be write on the eeprom but in my case eeprom address stop at 500 and the program try to write up to 1000.
    Maybe is it a problem with my arduino ( it is an arduino clone from china ... ) . I solve the problem when i modify some eeprom address .

    Second problem : Sometime the serial connection is so busy that refresh value on the screen don't work . Problem is now solved.

    I think that all should work before the end of the week. :)
     
  16. phil from seattle

    phil from seattle Journeyman
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    That capacitor will act as a low pass filter to prevent noise. Not exactly best practices but probably better than nothing. Make sure you use one with a fairly high rated voltage (50 would be good). Electrolytics can fail overvoltage with an electrolyte spewing pop.
     
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  17. phil from seattle

    phil from seattle Journeyman
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    And for what it's worth, I have finished the design of an isolated I2C based ADC with a built in divider. Boards are on their way to me from China so will soon be testing. Hopefully I won't have to make a revision. This is for grblHAL THC but they should work with any microcontroller that supports I2C.
     
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  18. HJackson02

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    Hi, thanks for your reply last time, I have been playing around with the code for the last couple days, I don’t really know what I am doing, don’t know much about this coding, once you get yours sorted can you post the code to see if it will work on mine. Thanks Harry

     
  19. Retsaj

    Retsaj New
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    Hey ya'll,

    I'm happy to see this project is useful for others and hardware differences aside I think its working for some of you. :)

    I've released a quick update to the sketch that allows the Actuator to return to 0 after the cut has finished and fixes a few minor IU things like reversed buttons. So far, its working great for me. I've posted a new section at the bottom of the build info about known issues and I'll post new versions there too when completed.

    The Nextion screen can be abit non-responsive at times and I think this is due to the serial interface. I'm looking a ways to improve the comms between the devices.

    It works without a cap if you raise the threshold voltage to not be triggered by noise but if you have bad noise problems a little cap is super cheap and helps smooth things alot. High Ferq starts from a plasma cutter can cause real problems too but I cannot help much there besides maybe to suggest adding a few a Iron Ferrite Core Noise Suppressors and maybe a complete isolation circuit. My plasma cutter doesn't have high ferq starts so I cannot offer much help here.

    Cheers!
     
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  20. phil from seattle

    phil from seattle Journeyman
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    By the way, a suggestion for your input filtering - use a real Low Pass Filter instead of just a capacitor. By using a 1K resistor and .1 uF (100nF) cap, you will filter out everything above 1.6KHz which is probably better than your capacitor alone. You can use a higher working voltage cap that way and increase safety margin significantly.

    Better yet, use something like my galvanically isolated ADC to protect your electronics (and self).
     

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  21. LeeArthur88

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    Thanks for sharing your design. I have ordered the components to build this project. I am working on a Ox based plasma table design. I am somewhat confused as to how the THC, Plasma cutter and CNC control board are connected and what signals are sent. The plasma cutter is an Everlast with the CPC port and machine torch. The CPC has connections for ON/Off, Raw Arc Voltage, Divided Arc Voltage and Arc OK. The schematic diagram shows the connections for the Divided Arc Voltage to the THC unit. The Raw Voltage from the plasma cutter is not used. Can anyone provide me with any information how the other two connections(On/Off, Arc OK) are made and will this THC work with a GRBL based controller or will it require a Mach3 type board.
    Thanks again.
     
  22. jerry fisher

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    Please tell me how to get the setting button's working, and if you could explain what there all for / do thank you. [email protected]
     
  23. mytechno3d

    mytechno3d Veteran
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    Yes !!!
    It is finaly working with my uno clone. :)
    I made several modifications to fit to my needs .
    I remove all preset ( i prefer so set manualy my arc votlage )
    All parameters are hard coded ( i prefer to not change them when i founded the right config and by this way i don't have any eeprom issue)
    I will post my uno and tft files tomorrow because i need to go to work and i'm already late ;-)
     
  24. phil from seattle

    phil from seattle Journeyman
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    I'm going to repeat my earlier comments but with more emphasis.

    [PSA Mode]
    This project is dangerous and unsafe as currently documented. The use of friction fit (jamming leads into an arduino socket) can easily lead to bad things. The use of an electrolytic capacitor is not a good idea. The lack of isolation is a big issue when the device on the other end of the wire is a plasma cutter. These are not theoretical objections.
    [/PSA Mode]
     
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  25. mytechno3d

    mytechno3d Veteran
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    You can try with this file.
    Arduino file and nexion display are included.
    Just let me know if it's work for you.
     

    Attached Files:

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  26. jsmith96

    jsmith96 New
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    I agree with what you said. some critical detail about sequence of operation is missing. Also details like MKS driver setup is not explained.
     
    #26 jsmith96, Feb 13, 2021
    Last edited by a moderator: Feb 13, 2021
  27. hottec2003

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    I installed several EEPROMex library and in the end almost everything works
    please can you post the library you would use in this project?

    regards!
     
  28. hottec2003

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    I would have been interested in the physical library EEPROmex used retsaj used

    in my case with one library the whole project works well, less float variable acces
     
  29. jsmith96

    jsmith96 New
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    Great work, I can not wait to try on my mega setup. I knew something was missing.
     
  30. jsmith96

    jsmith96 New
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    Let us watching your work if the mega is now functional. Can you make an iso file of the working sketch?
    Thanks
     

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