Butt welds with Hobart mig

[Bronco Sully]

I have a Hobart 140 mig welder. I am new to welding and have been practicing butt welding on multiple pieces with some success but not getting full penetration between the two pieces (this is for a patch panel in the kick panel for some rust I stumbled across while doing the floor pans). To be honest the results i have gotten are probably good enough for what I need but I am irked it's not 'full' mated all the way thru.

I am using 16 gauge mild untreated sheet metal. I wire wheeled all areas that are being welded to get them clean. According to my measurement tool, the kick panel is 16 gauge. I have been tacking around the pieces and waiting for the metal to cool to continue filling the gaps with further tack welds. I have ground down the test pieces and got smooth metal but on the back side there is still an obvious line.

Hobart has various settings (1-5 for power and 10-100 for feed). I have tried 2-4 on power and 20-40 for wire feed. The test pieces fit pretty tight with very small gaps. I am using shield gas as well with .030 wire. New machine so tips etc are new.

Anyone have any tips for this machine or Tips on getting full penetration without warping? Or are my results good enough for a non show truck?

Thanks!

 

[BRONCROB]

On the back of your machines door it has settings for wire size and material.Just play with your gap and heat on some scap until you get the results you want and remember to push not pull your wire.Some people like a little larger gap but on thin stuff I like to keep it a little wider than the wire.Good luck and remember to practice as much as needed in different positions.

 

[bax]

you got to push it. push it real good.

 

[Timmy390]

I have a Lincoln and have welded on my rig many many times. I prefer .035 wire for sheet metal work. I use flux core so I burn a touch hotter than gas shielded.

All the panels I've repaired have been 18 and 20 gauge on the Bronco.

Got any picks of the welds before you ground them down? Then back sides too?

Not seeing the welds, I would say the gaps are too tight between the pieces and maybe the wire feed is too fast. I found my Lincoln works best at a slower wire speed than listed on the machine.

Tim

 

[Timmy390]

Some people like a little larger gap but on thin stuff I like to keep it a little wider than the wire..

Same for me or just a bit larger. I find that works very well.

Tim

 

[Crawdad]

As Bax said, point the gun 30-60 degrees in the direction you are going. Also, double Chk ur amps. And what I mean is the wall outlet you are using may be 15A. Your machine may get better penetration using 20A. Also, try using a SS brush with isopropyl alcohol to clean area.

 

[Whoaa]

Turn the heat up and use a Copper backing plate. After welding one side, remove the backing plate, wire wheel and grind as nessesary, and then a simple cap weld to finish that side of the weld.

 

[Bronco Sully]

Thanks for the responses. Using the recommended setting of 3 and 30 got some better results tonight. I can get pretty much get full penetration but I am nervous that I will get warping as i need to hold the weld for multiple seconds ( saw some warping tonight).

I have a copper backing plate from Eastwood although the magnetic strength is almost worthless. If i use it on the patch panel i will need a clamp or something to keep it in place. It has been helpful on preventing blow throughs on my practice runs. Whoaa I like your idea.

I will look to see if I have pics of some of the welds. Will practice with the gaps between the panels tomorrow. Having better luck with very small gaps

 

[BRONCROB]

Just skip around and tack here and there.You can use a hammer and dolly to flatten the tacks while they are hot to prevent some of the warpage.You really don't want to run a full bead on thin stuff,just stack tacks slowly and randomly.

 

[Whoaa]

Generally speaking a store-bought "welding shoe" Copper backing plate doesn't work as well as a regular ol' piece of flat copper...because you can't form it easily to the contour you want, and it's difficult to clamp.

Grab a peice of common Copper water pipe, 1" diameter or whatever. Make a straight ripping cut down the side, pry open, then hammer flat. Make severak of these varying from about 2-3" in lenght to about 8-10" in lenght. Rig up what ever you have to get a solid and secure clamp aginst the back side of your weld.
If you don't have room to get a long-nose vise grip in place, weld 2 small tabs, one on either side of the weld, then drive a wedge shaped shim into place aginst the Copper -which will force the Copper backing plate to form perfect to your work, making a solid connection and fitting to the contour.
It takes time to get the backing plates to fit properly, and then move them everytime one section of weld is done. The actualy "welding" part is super easy if you have a well fitting backing plate, and the weld has 100% penetration....clean the other side -the side that had the backing plates after all of the face-side is complete, then a simple and quick cap weld to finish that side.

 

[Bronco Sully]

Will I get a bit more forgiveness when I actually put the panel in as I will have more metal to help dissipate the heat? My little practice panels are around 5 to 6 inches more or less. Just wondering.

Whoaa I your thoughts on a more malleable copper piece, makes sense. I think I will be able to use the off the shelf one I have given the roughly 4 x4 inch patch I will be doing. But I have some copper pipe laying around so I may go that route if I can't get a good fit.