ESAB Ultrarex UXD-P 2500 retrofit with Linuxcnc and Proma THC
Could you please tell me what would be the advantage of the Proma thc instead of using an arduino linked to the plasma’s voltage divider that sends the up/down signals to the 7i77 GPIO pins?
Is there any advantage besides noise insulation? I am trying to figure out if the cost of the Proma is worth it.
tommylight wrote: As Rod said, you can add an encoder to the existing DC motor and use a servo drive for Z axis.
I agree this, i can adapt an encoder but where to find an analogic servo driver? I suposse i cant find a new one on the market. If i wrong, please give me an advice.
I attach a picture with the motor .
Make sure you check the schematics for the drive to see if it uses +-10V or +5V and dir pins.
The THC is controlled through an RS232 originally, so i did not bother with it, just wired a drive to a stepper motor that i put on top of the existing motor after removing the tacho and using a coupling.
alexandrub wrote: Instead of encoder, can i use just the mesa or proma thc as ecoder? I touch of the metal sheet, lift up the torch a time...20ms for example and then start the cutting with thc control.
I wondered about that too. Its just the initial touch off that needs accuracy. Once you are cutting you could use a PID to manage the PWM signals with arc voltage as the feedback signal I'm sure. Its possible you could monitor the tacho until it stalls to set the material height. I did skim the manual for the motor and I think the tacho just outputs a DC voltage based on the speed. You may be able to use a 7i76e which has some analog voltage inputs to measure this voltage but it might need amplifying to get a good full scale reading.
Velocity mode servo can not be used without feedback for precise control.
It can be used for THC positioning but it requires using AD converters complicating things a lot.
The cheapest solution in this case is using an encoder, even one with very low count works as the motor is geared.
The easiest solution is to add a stepper motor and drive.