Hi Frequency TIG effects on CNC's

[boxcarbonz]

I just got a smokin deal on a MIller Syncrowave 200 TIG welder and was wondering about the High Frequency torch and how it will effect my CNC Plasma table and computer. I have a Thermal Dynamics Cutmaster 81 set up with a Dell computer running it. I haven't fired the torch yet till I can find some answers about how to shield the system, or if I really need to, from the HF waves...the book suggests grounding everything within a 50' radius of the torch. Has anybody had to do this or seen it done? Anxiosly awaitng to fire my new TIG up....Steve

[jimcolt]

I have worked with high frequency plasma systems and cnc machines for over 30 years. Since you are worried about a separate tig machine.....it most likely will not be an issue....however, your cnc machine should be properly eath grounded regardless. Grounding for electrical noise protection needs to be relatively simple...with too many ground wires a "ground loop" can be created which can make matters worse. RF (radio frequency) noise travels on the outside of conductors......and while there is very little current (amps).....the larger the wire diameter the more effective in conducting electrical noise to ground. The best type of grounding conductor is braided flat wire.....but large diameter stranded round cables are adequate. Here is the simple grounding scheme:

1. 10 foot copper coated (get it at Home Depot) ground rod driven through the shop floor into the earth.....as close as possible to the machine. Connecting to metal beams in the building is not good. Attach a terminal block securely on the ground rod to make all connections.

2. Run a wire directly from each of the following components directly to the ground rod terminal block....do not "daisy chain" wires. Cutting bed slats (this connection must be large enough to carry total cutting current of your plasma system), cutting machine frame, plasma power supply chassis, computer or cnc control chassis, any other electrical box chassis on your machine, gantry frame.

3. Attach the work cable from the plasma directly to the ground rod terminal block.

This is the KISS (keep it simple stupid) way of earth grounding....and should be in place on all cnc installations...regardless of whether there is a high frequency plasma or tig in the vicinity! If the cutting machine has further problems attributed to noise...then proper shields for all control cables (to motors, encoders, computer, thc, etc.) should be installed......with a shield drain from each shilded cable (from one end only) routed back to the ground rod terminal block as well.

Best regards, Jim Colt Hypertherm