I finally got my stepper motors working, x y and z. Attached my hand held torch and cut a few shapes. Sometimes, when the torch comes on, the G code stops, the computer is locked up. Even alt, ctl, Del does not work. Seems there is electromagnetic interference. I wrapped copper window screen aroung the printer cable and grounded the screen to the computer and it seemed to work sometimes. I have an Lteck plasma cutter with a high frequence start (that does not seem to work anymore since I hooked it up to the breakout relay for the switch. Any help or recommendations for the plasma machine type for use with Mach3 cam setup would be appreciated.

Alex

Hi, Alex

I think you need to Gnd. to a common point, I'm sure some will chime-in-on-this.

Thanks, Chip

I had a similar problem with my new plasma machine last weekend. It is a grounding issue with mine, I removed my box with all my electronics from the metal stand and it seemed to correct the problem. Problem was everytime the plasma started my steppers would start doing crazy things. I am going to rubber mount the controller box and try and isolate it from the table, havent dont it yet but it does work fine with the box not on the table. Hope this may be a little help.
Dave

who old is  is your plasma unit? does it use high frequency for the starting arc?older machines used high frequency pilot arc. have a 20 year old hypertherm powermax40  that i tried to use about 8 years ago , the instant it arced , the pc shut down.no amount of shielding would stop it.

i have use a hypertherm powermax 1100 since and never have any problems.

I have a Powermax 1000 that is about 1 month old. I still am going to have to isolate my electronics from the table, when mine is not connected to the table I dont have any problems. I have a dual-threshold pilot arc system on mine.
Dave

I have a L-Tec PCM 750i plasma cutter that is now supplied by ESAB. I bought it new in Nov 1994 for a little more than $2100 so I am motivated to get it to work. Sometimes it does not kill the computer and it works really well. I hope someone has experience with this machine and can offer some suggestions to get it to work. Are you saying that the steel on the table should be islolated from the stepper motor grounds, etc ? I think I can try this fairly easily.

My stepper motors are grounded thru the table, the problem only comes into effect when I have my steel cabinet that houses my electronics is bolted to the table. I havent isolated the cabinet yet, I need to tear it all down and powdercoat it then I will isolate it. Im not sure we are having the same problem but you can try and isolate your electronics, might work?
Dave