Uccnc converted Esab Ultrarex. Thc and Hypertherm cut charts issues

[SM1]

Hi!

Finally I have converted and modified my Esab Ultrarex Cnc plasma. I use UCCNC AXBB-E and their DC servo controllers to run the original DC servos for x and y. Stepper motor and ballscrew for the Z axis. Proma THC 150 to control height/arc voltage. Hypertherm Powermax 105 with machine torch.

I tried with the standard 45A Hypertherm nozzles and the suggested cut values. 6mm mild steel with 1350mm/min feed 137 Volts.

The THC will raise to the max allowed height of 10mm and still it doesn't reach 137V, around 133V at 10mm cutting height. All brand new OEM consumables.

I lowered the arc voltage down to 100V and then it seems to stay around 1-2.5mm cut height, unfortunately it doesn't seem to control the height very well. Maybe need to tweak the control parameters in the Proma 150? Or change the adjusting speed in UCCNC?
The arc voltage stays around 100V if I cut a small test part and set the cutting height to 1.5mm

I have tried 3mm mild steel and it behaves like with 6mm. Needs a much lower arc voltage to stay in the correct cut height. Why? Is the Hypertherm voltage values just scam or what could cause my issues? Competitors that normally use much lower voltages.

I appreciate all inputs I can get.

Kind regards,
Simon

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[weldguy]

In my experience Hypertherm's arc voltage specifications have been very accurate, I would suspect the Proma THC is the issue there. The good thing is that actual arc voltage value displayed to you by your Proma doesn't really matter, the important thing is that it is able to maintain an accurate cutting height. If it can do that then don't worry about the displayed voltage, just know the value your seeing is the one that holds the correct cut height, ignore the Hypertherm suggested value and use whats working for you. Awesome looking setup by the way!