Could somebody give me some advice when it comes to my welding

[semaj4712]

So I took a welding course ages ago, and started mig welding again off and on about a year ago, my welds are not pretty or even close to weldporn status, however they seem pretty strong, have good penetration and dont look awful.



But every now and then when my settings are correct, ill get more of a whoosh sound when i pull the trigger, i assume its the gas coming out, and then with the exact same settings it welds a really nice weld like this. It also sounds a lot less crackly and pools the weld really nice



My question is, is it possible that my welder is not always feeding gas properly and thus im technically welding with just the flux in the wire?

The welder is a Matco shop mig welder (mwld140) 180amp, i have not been able to find any information online about it. Any help is greatly appreciated

[deutschman]

Your not getting any shielding gas. Make sure you clean your tip/gas diffuser. Make sure your bottle is full, and the regulator is set correctly so that you are getting good flow.
Also you do not use gas with flux core wire. You use solid wire with gas, or you use flux core wire with no gas.
Flux core is best for welding outside when its windy or breezy, and the wind is blowing all your shielding gas away.
After you confirm you are getting a good flow of shielding gas and have the correct wire in your machine for welding with gas, check a few other things.
The wire thickens you should be using changes depending on the thickens of metal you are welding. Thin metal with thin wire because the wire needs less heat to weld and you dont burn holes as easily. Thick metal with thick wire (.035) because you will be welding much hotter.
Then make sure your heat is set for the material thickens you are working with.
Then adjust the wire speed until you get a nice even sizzling. If your wire speed is low you will hear a hesitation as the wire cant keep up with the rate of welding. If its to fast you will feel the wire push the gun away from the piece you are welding, and you will also here a hesitation in the welding. If you have your hood set right, you can also see the wire coming out to slow or to fast.
Your welder should have panel that recommends wire thickness, wire speed, and heat for the metal you are working with. I usually start there and then do fine adjustments because every welder is different, and the setting changing depending on how you are welding, up, down, push, pull. Also if your metal is free floating or on a surface that does not absorb heat quickly you will be welding nice and hot. But if your metal is on another fat piece of metal or concrete or something the material under the piece you are welding will suck up a bunch of heat and you will need to set your machine hotter.

[deutschman]

Also the speed at which you move your torch while welding changes the weld a lot. To fast and the weld wont penetrate. To slow and the weld will pile up.

[ForcedFirebird]

What pattern are you using?

Read up Miller's site, they have a lot of good tips. More than anything, though, practice - nothing is better than time under the hood.

http://www.millerwelds.com/resources/articles/Master-MIG-welding-GMAW

[semaj4712]

I figured it out, i bought this welder used and it turns out somebody had taken the gun apart and not put it together properly so it was turning the welder on but not opening thr gas, i fixed it for now but ordered a replacement gun which should fix the problem

[deutschman]

Yeah I figured it was a no gas issue. Good that you got it sorted.

[AndrewBird]

Critiquing your "nice" weld even further, it looks pretty good, but your control of the gun isn't great. Are you using both hands, one on the trigger the other as a steady rest? You want to keep the bead nice and straight. The edges of each side of the weld should be flat, not scalloped like yours. You could also travel a little slower, or turn your wire speed up slightly. The weld should be slightly convex, about as high as half the weld is wide, not flat or convex.

What motion are you using? I prefer a C shaped weave side to side, but others like an overlapping circular path, or on thick stuff, you can whip forward and back. This helps preheat the metal for better penetration. If you use the C shape weave, it can help to pause slightly on each side, only for less than a second though. This helps fill in some of the undercut.

[Ether-D]

More welding tips please! Best thread on r3v in weeks.

[mrsleeve]

On your good weld I see several decent sized gas pores that are open to the surface, with the shitty resolution of the same image, and the assumption that you laid a cap pass bead on a hunk of plate I am going to give you a benefit of the doubt on a size-able area of external undercut (as thats kinda hard to do on a hunk of plate) and blame what I see on the image.

t

[semaj4712]

Thanks for the tips, as I stated I am no expert, the weld was done with a circular overlapping motion, but I was working on a patch panel in the trans tunnel and was upside down under a car, so I know its not great, I only could get one arm in there so wasn't able to stabilize