Advice for plug welding with mig welder

[duffman]

Hi just bought a nice little rtec 181 welder and getting to grips with it. I have a project car restoration to do and just testing out the settings on some plugs welds on 0.8mm sheet metal. I've attached a few photos of the practice spot on some old chassis. I feel it might have a little too much penetration. Looking some advice, the two lower spot welds I did were @ 17.5 volts and 10.0 metre/min wire speed. The 3 upper spots were slightly hotter.

Any tips welcome. Cheers.

 

[tigdlo]

I would be aiming to replicate a comlete and consistant version the bottom 2, the one on the left in the 3rd picture looks incomplete at the 7 o'clock position which I would consider to be a weld fault.

What size holes did you drill?

 

[123hotchef]

spot welds or plug welds? I am confused now.

 

[duffman]

spot welds or plug welds? I am confused now

Plug weld.

 

[duffman]

I would be aiming to replicate a comlete and consistant version the bottom 2, the one on the left in the 3rd picture looks incomplete at the 7 o'clock position which I would consider to be a weld fault.

What size holes did you drill?

Yes my thinking as well. The lower plugs were done with a slight lower voltage. Not heating up the metal too much. That spot looks like it has some soot on it. It's too hot I think as the wire feed was slower and took longer to fill up the hole.

Holes are 7.5mm I drilled factory spots out. Good 150 to weld. New chassis being replaced just want to get the settings fine tuned before I start.

 

[caprinut]

spot welds or plug welds? I am confused now.

A spot weld is where you have a machine that clamps two pieces of material together and then sends and electric charge through to create the weld. A plug weld is where you cut a hole in one piece sometimes both pieces of material, clamp and then fill the the hole with weld.

 

[duffman]

A spot weld is where you have a machine that clamps two pieces of material together and then sends and electric charge through to create the weld. A plug weld is where you cut a hole in one piece sometimes both pieces of material, clamp and then fill the the hole with weld.

Yes it's the latter that you have described. I have used the two terms interchangeably. I understand both are different. Any how you would have known from the photos which one I was talking about from the heat disapiation.

 

[Keithmac]

I found a bigger hole worked better for my plug welds, think my hole punch was 5mm but ended up at 6mm or 7mm iirc.

 

[tigdlo]

I found a bigger hole worked better for my plug welds, think my hole punch was 5mm but ended up at 6mm or 7mm iirc.

Yes, the hole will fill up before getting full penetration on the other panel, I have found 7mm about right for 0.8mm to 1mm if both panels are the same thickness.

 

[Pigeon_Droppings2]

Are you positive that the sheets were clamped tightly....I use a pair of grips and do each one in turn but there are tools you can buy specifically for clamping plugs I think.

I've found if the clamping isn't right enough then the to sheet has a sort of burn under rather than a nice spot. You can see it as a gap when you grind them flush.

 

[Onthespotwelding]

Our very own @doubleboost has done a review on the R-Tech mig 181.

Very thorough review including Plug welds.

 

[paulo1974]

change the wire to 0.6 wire

 

[Keithmac]

Are you positive that the sheets were clamped tightly....I use a pair of grips and do each one in turn but there are tools you can buy specifically for clamping plugs I think.

I've found if the clamping isn't right enough then the to sheet has a sort of burn under rather than a nice spot. You can see it as a gap when you grind them flush.

Yes I bought a couple of pairs of plug weld mole grips (the back has a copper pad and the front is split into a Y to clamp the panels and allow torch access).

Makes the job a lot easier.

 

[duffman]

change the wire to 0.6 wire

I'm running 0.6 wire

 

[duffman]

Yes, the hole will fill up before getting full penetration on the other panel, I have found 7mm about right for 0.8mm to 1mm if both panels are the same thickness.

I had to drill out the factory spotwelds on the boot floor connecting the chassis legs. I used a 7.5mm bit. I was using the 1.5mm preset settings on this mig which worked okay but might need to up the wire speed another bit as it was taking about 2.5 seconds to fill the hole.

 

[duffman]

Yes I bought a couple of pairs of plug weld mole grips (the back has a copper pad and the front is split into a Y to clamp the panels and allow torch access).

Makes the job a lot easier.

I've wingtip clecos I'm gonna use as can't use grips for what I'm doing. I did have grips in place before welding. For filling plugs what on 0.8mm have you found running hotter and a faster wire speed is better.

 

[duffman]

Are you positive that the sheets were clamped tightly....I use a pair of grips and do each one in turn but there are tools you can buy specifically for clamping plugs I think.

I've found if the clamping isn't right enough then the to sheet has a sort of burn under rather than a nice spot. You can see it as a gap when you grind them flush.

Yep the sheets were clamped with normal grips which was a tight fit.

 

[Keithmac]

I've wingtip clecos I'm gonna use as can't use grips for what I'm doing. I did have grips in place before welding. For filling plugs what on 0.8mm have you found running hotter and a faster wire speed is better.

I ran it as close to blowing a hole in the second panel as possible. Probably 3 seconds a plug weld iirc.

I would rather have good penetration with a couple of blow throughs than a half welded panel.

You get the hang of it pretty quickly when you get going.

5mm holes were no good and didn't give a stong weld for me.

 

[duffman]

I ran it as close to blowing a hole in the second panel as possible. Probably 3 seconds a plug weld iirc.

I would rather have good penetration with a couple of blow throughs than a half welded panel.

You get the hang of it pretty quickly when you get going.

5mm holes were no good and didn't give a stong weld for me.

Don't want too much pentration were it distorts the metal and causes rusting down the line. Fine line between too much and too little. Gonna fiddle around with the settings another bit till I get it perfect then get to work after that haha.

 

[GRW]

I tried some plug welds when doing the floor in my old van - & I used 5mm holes.
It was my first attempt, so wasn't really sure what I was doing tbh.
It's interesting to read that larger 7mm-ish holes in the face metal works better.