Spot welding with mig

[red61cj5]

I will be replacing a few floor panels (like the whole floor) in my willys jeep over this winter. Most of the panels were originally spot welded in place and I plan to do the same for the less visible areas. Has anyone used their mig to spot weld? Any extra equipment I need? I've seen the stand off nozzles made for it. Also, can I use flux wire or should I use gas? I'm using a Hobart 140, if that matters.

 

[Spareparts]

It is called Plug Welding do it all the time, I have a Roper Whitney punch, just punch holes line it up and plug weld it up, on the bottom side use some seam sealer to seal the overlap or it will rust in that seam, or **** weld it with no overlap.

 

[ddawg16]

Good questions.....I've spot welded before...like when I'm getting pieces in place before I run the full bead. So, I seen no reason you couldn't use either method.....though I'm inclined to say gas. I'd only use flux for hard to get to locations and when vertical.

 

[bri_man57]

Yep, like others are saying, punch or drill holes and just weld those holes up to the base material.

Sent from my SM-N920T using Tapatalk

 

[oldwino]

The standoff nozzles like Eastwood sounded like a good idea. Used it once and decided it is just as easy to do without. I’ve only used gas but have only worked on a horizontal surface

 

[DTE]

If I am overlapping I just drill the top piece, here is a floor in a truck I am working on , where the panels are butted they are on top of square tubing. I use 030 wire and I always use gas.

 

[Tinker2]

Plug welding [rosette welding in the aviation/airframe world]-

Not to be confused with tack welding a **** seam or spot welding using a spot welder. Tip: use weld through primer on the mating surfaces prior to welding.

 

[Gotcha640]

Harbor freight air punch is great if the steel is thin enough. If you have to drill all the holes, I know I would end up bending something out of shape, or getting lazy and not doing enough, or whatever. My shoulder wouldn't like holding the drill for the hundred or whatever holes (seems like every ~2-3 inches recommended).

https://www.harborfreight.com/air-punch-flange-tool-1110.html

 

[DTE]

Also you will need a way to clamp the panels tight together or use some # 10/12 machine screws and bolt the pieces together if a clamp won't fit and then go back and weld those holes up.

 

[MoonRise]

Rosette weld.

Go read the thread from MP&C and look at his write up all about car body work and repair and such.

Come back in about a week after reading through his nice and LONG thread.

Oh, and use GMAW aka MIG. Solid wire, usually 0.025, and C25 shielding gas.

 

[MP&C]

Welding plug welds....

Grinding plug welds....

 

[brainypencil]

Welding plug welds....

Grinding plug welds....

It is indeed helpful. Thanks

 

[Slednut]

Welding plug welds....

Grinding plug welds....

I don't know about anyone else but for some reason I really enjoy doing these welds.

 

[brandonsmash]

Easy peasy. Plug welding can be done with no additional tools other than a drill or punch for the top piece.

 

[latebreak]

eastwood and others make a nice pneumatic flanger / punch depending upon if you need to flange your pans or not.

 

[abachman]

If you are drilling through both layers, you may want to use a piece of heavy copper as a backing. The weld will not stick to the copper. It just keeps the weld from building too much on the bottom side.

 

[red61cj5]

I'm reviving this thread for another stupid question. Gas settings? I went and got a tank of 75/25, but have no idea of how much to flow, anyone have a starting point for me?

 

[king nero]

For thin sheet metal work, a mixed gas with lower % CO2 works better. 90/10 or similar.
Flow rate for low energy welding is 10 - 12 liters/min or 21 - 25 cf/hour
For these low flow rates, make sure there is no draught in your shop, as the shielding gas can easily be blown away.

 

[shawhite]

I'm reviving this thread for another stupid question. Gas settings? I went and got a tank of 75/25, but have no idea of how much to flow, anyone have a starting point for me?

Usually the inside of the door of your welder will give you a range for the wire size you are using. Most of the time that is a good starting point but you may find you need to increase it depending on your environment (inside, outside, drafty etc)

 

[WoodsTruck]

I have plug welded panels using my pneumatic hole punch. When I ordered it, I had the option of two hole sizes and I went with the smaller hole. I wish I remembered where I bought it as the large hole would have worked better. The smaller hole has a tendency to bridge the weld bead over and though it looks like a nice button there is minimal penetration through to the bottom piece. With a larger hole, it would force a small internal bead to be developed onto the bottom piece before filling in the center. If I'm concerned this will be an issue I will double punch a hole so it is almost double width which gives the bottom piece time to melt and bond.

 

[bri_man57]

I used c25 mix, I'm not sure I would get a special bottle of gas only for sheet metal unless that's all I was doing. I run my regulator somewhere around 12 to 15.



Sent from my SM-N920T using Tapatalk

 

[no704]

Not welding related, but a hand full of clecos make sheat metal mock up much easier!

 

[MoonRise]

I'm reviving this thread for another stupid question. Gas settings? I went and got a tank of 75/25, but have no idea of how much to flow, anyone have a starting point for me?

RTFM for your welder.

The usual shielding gas flow rate for 'small' MIG machines is around 20 cfh, give or take. For pretty much any weld. **** weld, or lap weld, or fillet weld, or plug/rosette weld.

Same with any new weld procedure, practice on some scrap first.

 

[astroracer]

I am running a 75/25 mix, .032 wire diameter, no special nozzle and absolutely no "weld-thru primer".... I have a hand held punch I built a bench mount for and one of the HF crimper/punch tools. The hand held is more versatile but the air powered one is a great arm saver when doing long runs like a floor pan.
I have done hundreds of plug welds building my Astro Van and rebuilding my '56 wagon. The MiG does an excellent job doing these but it will take a little bit to get the settings correct. Once you get them figured out pretty welds are the norm.
Here are a few pics of some of the welds my machine can do. Your results may vary.
These are the floors in my wagon.



I also rebuilt both inner and outer cowls in this car and all of the patch panels were installed with plug welds.
Mark