[Skiroy]

I had to Tig weld(208V) a machine that has proprietary motherboards and electronics on board and is a 208V machine. I turned it off but left it plugged in with the thought that if the TIG welder current were to stray it would go into the earth ground connection. But today we are having an anomaly and I am hoping I didnt fry something.

What is the proper procedure when welding on a machine that has electronics on board?

[Al_The_Man]

Depends if the electronics were left powered? But normally no damage should occur in the normal course of events.
There are many Plasma and welding CNC machines that have electronics on board, the main thing is the grounding and bonding to a central Earth ground point.
If this is a commercial machine, I would expect that it has this in place already?
Al.

[Skiroy]

Depends if the electronics were left powered? But normally no damage should occur in the normal course of events.
There are many Plasma and welding CNC machines that have electronics on board, the main thing is the grounding and bonding to a central Earth ground point.
If this is a commercial machine, I would expect that it has this in place already?
Al.

Yes its a commercial machine it was powered off and the main switch/breaker that supplys the 208V to the machine was off so no power should been going to the machine. It is all bonded but the question is if the main switch is off if the earth ground is still in place which I assume is because its 3 phase and the switch only has the 3 phase going through it.

So then this electronic anamoly is just coincedence and I did fine by simply turning the machine off when I welded on it?

[Al_The_Man]

The main thing is is to try and keep all welding current local to the weld point in question, IOW the TIG return lead should be placed as close as possible to the weld point.
Otherwise it is hard to know exactly what the effects are if the return lead is placed remotely where currents could flow, depending on how the electronics are ground bonded or whether isolated?
Removing power to the electronics is also the other primary precaution.
Al.

[Skiroy]

Thankx Al

[jeffrey001]

I've seen a couple of CNC machine scrap after welding a part that had a hole cut too big and the guy weld a plug in the hole.

All bearings on the machine were scrap.

Not a thing I would do on my CNC.

Jeff

[gmfoster]

Jeff that would depend on where the welder ground was placed. If done properly there is nothing that could harm a bearing. But telling a welder how to do his job can be the tough part.

[jeffrey001]

Jeff that would depend on where the welder ground was placed. If done properly there is nothing that could harm a bearing. But telling a welder how to do his job can be the tough part.

Yes I know but on one particular time, the welder touch the groud clamp with his leg and it drop on the frame.

For me, it's simply too dangerous to do that.

Jeff

[Skiroy]

Okay something that has stumped me is I tried to weld a cracked assembly today(TIG) and the crack just would not go away. It was steel and I was on DC-. Another thing that was weird was the slag would pop off and literally fly at you. I have never seen this before. We welded it 4 times and it just would never get rid of the crack. Then we tried to MIG weld it and it took just fine.

Any insight?

[Skiroy]

Nothing? Another thing my co worker unplugged it when he welded it. I thought this was bad because by unplugging it you disconnect the Earth ground the machine is bonded to. He argued with me.

[Skiroy]

bump