Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: vcp on November 23, 2013, 10:28:52 PM

Title: Best settings for plasma cutting holes
Post by: vcp on November 23, 2013, 10:28:52 PM

Im having chronic hole cutting issues with my Plasma. The holes are nice and smooth, taper isnt bad...however, after every cut, the torch will stop moving and the arc will remain on for 1-2 seconds before extinguishing. The result is a nasty blowout from right where the torch stopped cutting.

Can anyone give me some tips on how to either program the arc to turn off sooner or a different work around.

Geoff

Title: Re: Best settings for plasma cutting holes
Post by: Scott594 on November 24, 2013, 05:14:28 AM

Geoff,

I'm the consumate newbie on the CNC end of this subject, having just joined because I decided to convert my electrically driven manual lathe and mill (mini asian varieties).

I, do, however have a long history with welding and cutting equipment.

 Some plasma machines establish and quench the arc by moving the gun electrodes apart with the plasma feed gas (air in most machines). The shutdown switch closes the air valve, which allows the arc electrodes to fall back together (they're spring loaded), thus opening the contactor. If your machine uses this system (Hypertherm does at least in some of their machines - I have one), then there is a delay while the pressurized air lines past the valve bleed down thru the nozzle. during this time the plasma flow continues. It's unnoticable in manual operation unless you are aware of it.

This might be what is happening, and close observation of the shut-down should determine if it's the problem. If so, minimizing the pressure and volume of the lines past the solenoid valve will help. You my be able to wire the contactor so your CNC relay opens the contactor directly, but that may interfere with the arc establishment sequence. A different nozzle spring may help too, but I'm just guessing there. The plasma cutter manufacturer couls say for sure.

If not, sorry to waste your time. I'm sure these guys will help you solve it.

Scott

Title: Re: Best settings for plasma cutting holes
Post by: BR549 on November 24, 2013, 10:56:31 AM

Check your M5s for delays either in the config or Gcode.

(;-) TP

Title: Re: Best settings for plasma cutting holes
Post by: vcp on November 24, 2013, 12:24:29 PM

Thanks for the quick responses, where should I look for delays in the config?

Also, my setup is:
5x10 Lightning CNC
Hypertherm Powermax 45 using Hand Torch & Machine Shield
NO THC YET
Cutting 1/8" & 1/4" mild steel plate