View Full Version : Question on joining metal, two ground wires for mig/flux core welder?

01-10-2009, 11:35 AM
I'm continuing to experiment and trying to join two pieces with my 90amp mig/flux core welder.

One piece has the grounding clip, the other does not. Given this, current will want to flow towards the side with the ground, which will not make for a good even weld, with even heat. I see this in my test welds.

If the two pieces are clamped with a lot of overlap it's not much of a problem.
But these projects demand of all kinds of crazy joins (Streetfox fishmouths..)

I wish the ground clip was split with two clips on the end to attached to both pieces. I've considered using my jumper cable.

But of course that would extend circuit even more. I've discovered as others here have, that the closer you can get to the breaker box with thicker wires the better off you are with a 90amp 115v welder.

Curious how the 'crew solves this kind of problem.

Thanks for all your help! This is good phun!


01-10-2009, 12:00 PM
Tomas - you should be putting a tack weld at each end of the two pieces you intend to weld anyway. That keeps the far end from separating as the metal heats up. When you do a tack, start on the side with the clamp and once the puddle forms just bridge it across to the other piece. That should give you plenty of connection for the rest of the weld. Works for me anyway.

01-10-2009, 02:11 PM
Tomas pretty much what Trikeman said here as well put a few tacks on the pieces in question also try to get your joints as tight as possible before welding this will help as well.


01-23-2009, 07:58 AM
hi tomas to get good penetration on both sides of the joint make sure you aim the wire/gun dead center and if ther is a gap weve slitly from side to side
hope this helps


01-23-2009, 09:19 AM
If your joining 2 pieces side by side leave a gap of approx 1/8" to 5/16, if the 2 sides touch its only the weld that holds them together and the 2 parts can be bent back and broken, rather like scoring halfway through card to fold and bend it.
If the metal is bluey/black from scale ie like angle iron, file it off for the join.
Its easy to weld over the scale but often the weld just sticks on it without fusing to the parent metal underneath.
Tack both ends as mentioned above.
I find a really good joint is made if you stand the piece up vertical at about eye height and start welding from the top tack downwards weaving side to side but still keeping the wire in the weld pool. You must be able to see the gun tip and weld pool at all times.
I've found this to be a fast method, less chance of blow through and excellent fusion
You can weld across a huge gap this way (once the first bridge is made)

If the second piece is laying on top of the first still remove any scale and tack them in place, if its thin stuff the above still works very well, if its thick with no chance of blow through then on the bench is ok.
If its a fillet weld, ie, one piece standing on the other and you must weld into a corner, vertical down or flat on the bench both work.