Qtplasmac with proma thc 150 Z axis up and down too quick!

Hi all,
I have helped a friend to mount a plasma cnc using linuxcnc with qtplasmac gui, the working area is with 3000x2100mm, Z travel with 350mm for perhaps in the future install a rotary axis.

We install proma thc 150 and all works really well until we start to cut 20mm of steel.
The Z axis starts to go up and down very quick causing bad quality in the cut, for this height of 20mm we have setup the plasma with 87 amps and proma thc 150 with 152 volts at a feedrate of 400 mm/minute.

The plasma is a Roluk inverter cut 100 HF with Autocut A 101P torche.
Until 10/15mm of cuting all runs good but cutting 20mm the quality isn´t so good, this plasma is anounced to be bable to manual cutting until 45mm  so even discounting some for cnc cutting it should be "easy" to cut 20mm.

Any help will be apreciated, thank you in advance.

In the settings page, set the P value for THC to 9 or 8 from the default 10.
You can also set the Z speed lower, but when cutting thin sheets that would need to be changed again.

We have changed the P value to 8, minor changes in cut quality, then to 6 then to 7 and it seems 7 is the value, very thanks.
Maybe tomorow we will change the z axis speed.
How can we change z axis cut speed without change in stepconfig?

thank you very much for your attention i will give feed back.

Same page, setup speed, probably but not sure if that also limits THC speed.
Does not hurt to try.

Thank you Tommy.
We think z axis is really really with huge speed, we have exagerated on purpose and fine cut height with this setup is with value of P=3%.
So tomorow we will balance the speed of z axis, we have speed up the z axis to speed up probe speed because we have a floating switch.
In sheets with 2x1,5m cutting pieces with 200x100mm and so, probe speed is a issue if is slow, so perhaps we will fine tune this to balance the speed workflow.

thank you

tommylight wrote:

Same page, setup speed, probably but not sure if that also limits THC speed.
Does not hurt to try.

Setup Speed is all plasmac Z axis motion except for THC which uses MAX_VELOCITY from the ini file.