Really good job ,
I will build one to try it on my diy plasma table..
Thanks for sharing .

 

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.

 

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.

 

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.

 

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

 

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

 

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

 

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.

 

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.

 

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.

 

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

 

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).

 

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.

 

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]

 

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 ;-)

 

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]

 

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

 

I agree with what you said. some critical detail about sequence of operation is missing. Also details like MKS driver setup is not explained.

 

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!

 

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

 

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

 

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