Plasma fires and makes Estop

[twicecustom]

I have a problem that has been giving me a hard time.
I'm using steppers, Gecko G540, and CandCNC LCTCH.  When the program calls for torch on, it brings up Estop as soon as an arc fires.  But If I go to the torch handle and manually fire the torch it doesn't cause a problem.  I have unhooked all the motors from the G540 and it still faults out. I have no limit switches hooked up or turned on in the profile.  I ran good grounds in the star config to a 7' copper coated rod driven in the ground.  I changed Debounce way up and all over the place and it still doesn't work.. Anyone have any ideas???

[rrc1962]

It sounds like the THC might be sending an estop to Mach for some reason.  I can't think of a reason why a THC would need to estop the system, but I don't know anything about the CandCNC THC either.  That or you might have some pins in your configuration crossed up so activating OUTPUT1 is actually sending an estop.

[twicecustom]

It works some days, then other days it just wont work at all... 

[rrc1962]

If it's intermittent, it's probably noise tripping the estop.  How is your estop wired?  I use a G540 and I have 3 estop push buttons and limit switches all wired in series and connected to the G540 enable.  Opening that circuit faults the drive and the drive sends an estop request to mach.

[toomanyhobbies]

Wow, I wish I could help you, I have been having the same problem with the plasma cutter on my cnc! I get random windows popping up on the computer and an instantaneous Estop when the torch lights. It has to be noise from the torch. I spoke to a Miller rep and he suggested contacting someone at Miller that may know what is causing this as it could be an internal problem in the plasma cutter. Strange because it worked perfectly fine for years then all of a sudden it won't work right anymore.

Anyway, good luck, I'm gonna follow this thread, interested to see what you find out.

[larryc]

Did either of you get a new torch. I read some place in a torch pamflit about cnc controling of plasma torches and It said that some plasma torches woud trip the e stop. If I remember right some torches use a high frequncy arc to start the torch. And this caused a feed back through the input cable. they said to make sure all the cable was well sheided and grounded.I cant recall everything that was said but I came away with the understanding of dont use a torch with high frequency starter. might be somthing to check.

[rrc1962]

Wow, I wish I could help you, I have been having the same problem with the plasma cutter on my cnc!

Are you using the CandCNC THC also?  Just looking for common denominators. 

Most machines these days less that 120A are not HF start.  I know that TD doesn't go to HF until you get into the high definition machines.  HF causes a lot of problems and the manufacturers are starting to realize that.  My welder supplier installed a big HF TIG in a hangar out at the airport for welding aluminum.  The HF virtually shut down radio communications around the airport.  They eventually had to move the machine to a location off the field.

[toomanyhobbies]

No, I'm not using CandCNC. No torch height control.

Also noticed my plasma cutter will interfere with the computer just by being near it. It's not even necessary to have a connection to the cnc table, although it is noticeably worse when it is connected.

Maybe some ferrite cores on the THC cables will help you?

[toomanyhobbies]

Also, are your cables (thc, motors, parallel cable) all shielded and well grounded?  i wonder if it would help to shield the torch cable? Just a few thoughts...

[rrc1962]

Everything is shielded on my machine and grounded at the controller.  Other than the ground clamp from the plasma, which I connect to the work, not the table, the table itself is not grounded at all.  The plasma is a Thermal Dynamics Cutmaster 152. 

Sounds like you have either HF start or one of those Chinese plasma machines.  My neighbor has a harbor freight plasma and when he fires it (400 feet away in his garage), our TV goes all wacky.