Proma thc issues with first cut of the day

[SteelValleyForge]

Hi all. I am new to the cnc plasma cutting and I ran into a problem yesterday on the first cut of the day. So I cut these parts out on Tuesday using the tch everything was cool fired the machine back up on wednesday and ran the exact same g code nothing changed voltage was set to 113 with give me the perfect cut hight for 1/2" plate. Went to go start the cut turn on the thc it rode at 95 volts and wouldn't chance and the torch crashed into the plate. Cut another part with the thc off all good 3rd part flipped the thc back on everything went well for the remaining 12 parts. Why doesnt it work on the first cut of the day??. I ran into this problem when 16 gauge as well. Different setting of course..
Machine is premier plasma cnc 5x10 cutter is hypertherm 85 sync running at hypertherm specs from book. Any help or reasoning would be great ! Thanks

[Nemo]

What settings are you using on the Proma?

[05Duramax]

That is very strange, wish I had a clue what would cause that. On a positive note at least it works after the first cut, I have fought with thc's that never ended up working! Hopefully Nemo has an idea when you get the settings posted.

[4130metalworks]

Have you checked the cut height with feeler gauges?
Is the thc feed rate not set too low?
Is the work clamp on the material? Also try grinding off the mill scale so the clamp has less electronic resistance
Air pressure up enough ?
Correct consumables?
Correct post processor?

These are all the things i have done wrong before that gave arc voltage issues

[acourtjester]

First off understand the start of a cut and the start of the THC are 2 different operations. The start of the cut height is controlled by either a floating head switch or Ohmic sensing. Which is selected by the G-code as to which it uses as the codes are different, and this effects the setting of the torch height for the pierce height (different for metal thickness). There is also a pierce delay for the plasma to complete the cut through the metal, and different due to the metal thickness too. After the completion of the pierce the torch starts to move, now there is the delay for the arc to stabilize before the THC starts to control the torch height. The pierce delay is controlled by the G-code and the stabilize delay is controlled by the THC module setting. If the stabilizing delay is to short the arc voltage is erratic, this can cause the THC to crash the torch. I would have at least 1.5 second delay on the THC before it starts controlling the torch height. And the THC voltage is set manually (Proma) do you check it for each start of cutting to be sure it is for that thickness of metal??