# Heads Up on Proper Grounding (Miller Multimatic 215)



## Roboticist (May 22, 2018)

*Short Version:* Ensure your ground is has complete conductivity with your workpiece. A loose connection can cause increased resistance and fry the welder's PCB.

Let me preference by saying the Multimatic 215 is an absolutely fantastic machine that I use/ abuse regularly (300+ hrs/ year).

When I turned on my machine after being out of town for a week the machine said a spoolgun was attached instead of the MIG gun I had on it. So, when I pressed the trigger everything worked, except the wire feed motor wouldn't turn. The motor tested fine, but the circuit was not pushing power to the motor (because it thought a spoolgun was attached). I took it in to my LWS and they said if your ground becomes loose (but still attached) the increased resistance can be enough to damage the control board. They were kind enough to loan me one of their rentals, for free, while they were working on getting my machine fixed.

I made a tab for my table and put some in Dinse panel mount sockets to hopefully avoid this in the future.


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## Aukai (May 22, 2018)

Thank you for posting that.


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## Janderso (May 23, 2018)

I am new to TIG/MIG welding. I plan on clamping to the frame of my new Certiflat welding table. Is that adequate for anything I set on the table to be welded?
What are the rules here? Thank you for your help.
I have a Miller Diversion 180-so far I love it!


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## Roboticist (May 23, 2018)

Janderso said:


> I am new to TIG/MIG welding. I plan on clamping to the frame of my new Certiflat welding table. Is that adequate for anything I set on the table to be welded?
> What are the rules here? Thank you for your help.
> I have a Miller Diversion 180-so far I love it!



*Short Version:* Yes, if you have your ground secured to your Certiflat table anything set on the table will be grounded. To ensure a proper ground ditch the spring-loaded clamp and get a more secure clamp. Two options are linked below.

The Diversion is a great machine, I'm glad you're enjoying it. I'm unsure as to how sensitive the Diversion is to this issue, but I'm inclined to say it is less problematic due to the nature of its circuitry. My rationale for this is twofold; the circuitry on the Diversion (and any AC TIG machine) is more robust than the Multimatic 215, largely because they turned the Millermatic 211 case into a multiprocess machine, and my Dynasty is still running like a champ.

With that said, I am personally taking no chances and have made sure the ground connections are firmly affixed to the table.

To answer your question, yes, if you have your ground secured to your Certiflat table anything set on the table will be grounded. This is very common practice, it is how my personal table is setup, as well as the bot in my lab. I can post pictures of how I have it on my table later if you'd like. This is however assuming there is good conductivity between your workpiece and table. If you ever see little porous dots (typically about the size of a pea) on your table it means there was not proper conductivity between your table and workpiece. This will cause an arc between the two in a localized place resulting in these little arc scars. This is particularly evident when welding aluminum, which is why it is good practice to get a block of aluminum to put on your table and weld up your piece on top of the block, using the block as an intermediary work surface of sorts. 

One option is to crimp a cable lug onto your ground cable and then bolt that to your table. If you would like for the cable to be easily removable I would opt for a clamp that is not spring loaded. If you want to be able to switch out the clamp type you can always put a cable-to-cable connection about a foot behind the clamp. 

Two possible options are linked below:

https://www.arc-zone.com/ground-clamp-mig-600

https://www.arc-zone.com/the-ground-hog-clamp-gp95


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## Aukai (May 23, 2018)

I have a certiflat table and welding with my 211 will at times weld the object to the table at the contact points. I try to grab the welded object with the ground lead. My used syncrowave 250 is in for a circuit board repair, that's how I bought it.


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## Roboticist (May 23, 2018)

Sticking to the table is typical, nothing to worry about it, unless you're an uber perfectionist. I usually just smack it with my fist, hammer, boot, whatever is within arms reach and drive on.


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## 682bear (May 23, 2018)

Keep in mind that any contamination, paint, dirt, oil, mill scale, dust, or just about anything else between your work and table will also increase the resistance in the circuit... potentially leading to the same problem.

I have my table permanantly grounded to the welder and also use a spring clamp directly to the work (if the work is big enough to use the clamp on). You can't be grounded too well...

-Bear


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## Janderso (May 23, 2018)

Wow, sticking to the table?
Maybe it is a good idea to overground the work piece by having the table and the job piece grounded.


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## 682bear (May 23, 2018)

Actually, sticking to the table is a sign that the part is not well grounded. The current has to arc from the part to the table... causing the sticking

-Bear


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## f350ca (May 23, 2018)

Poor grounds are common, at least for me. I beter stick (pun intended) to transformer technology I guess.

Greg


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## Janderso (May 23, 2018)

So, Mr. bear,
I assume you do not recommend just grounding the table.
I don’t have the experience to make the following assumption but here I go.
If the piece has full contact, a large area to transfer a grounded point, the table ground would be adequate.
If an angled piece with just a few points on the table, best to ground the piece.
Imho


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## Buffalo21 (May 23, 2018)

f350ca said:


> Poor grounds are common, at least for me. I beter stick (pun intended) to transformer technology I guess.
> 
> Greg


According to my BIL, a MIller tech, that if a bad ground caused the problem, that would be a major design flaw in the welder, as loose or bad grounds are one of the most common issues with a welder. He said the customer should call Miller’s customer service and describe the issue, because if it was an issue of any kind, there would be numerous service bulletins., which he said he has never seen.


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## Ray C (May 24, 2018)

Buffalo21 said:


> According to my BIL, a MIller tech, that if a bad ground caused the problem, that would be a major design flaw in the welder, as loose or bad grounds are one of the most common issues with a welder. He said the customer should call Miller’s customer service and describe the issue, because if it was an issue of any kind, there would be numerous service bulletins., which he said he has never seen.



I'm really glad you said this because I've been watching this post and scratching my head.   I do a fair bit of welding and have lost ground more times than I can count with no less than 4 different welding units.  It usually happens when I switch cable sets and connect the wrong ground clamp to the table stud.  I've had plenty of weak grounds from not cleaning the table or getting enough of the scale off the subject piece.   This has never caused a problem with the equipment.

If the machine sees a lot of use, maybe something just went bad due to natural failure.  -It happens...  -Nothing mechanical or electrical is perfect forever.  

Ray


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## 682bear (May 24, 2018)

Janderso said:


> So, Mr. bear,
> I assume you do not recommend just grounding the table.
> I don’t have the experience to make the following assumption but here I go.
> If the piece has full contact, a large area to transfer a grounded point, the table ground would be adequate.
> ...





682bear said:


> Keep in mind that any contamination, paint, dirt, oil, mill scale, dust, or just about anything else between your work and table will also increase the resistance in the circuit... potentially leading to the same problem.
> 
> I have my table permanantly grounded to the welder and also use a spring clamp directly to the work (if the work is big enough to use the clamp on). You can't be grounded too well...
> 
> -Bear



Post #7... 

-Bear


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