Find the sweet spot on the MIG

MIG Welding

For those of you who are new to MIG welding and who might be struggling to set the welder up to achieve a good result, this article may go some way to helping you understand what’s happening when you are trying to weld something together. 

Basic Controls

The very basic welder will have variable controls for;

  1. Power or volts usually on a dial or block increments switch 
  2. Wire speed ( the speed of the mig wire coming out of the end of the torch )
  3. Shielding gas flow. ( usually on a flow gauge on top of a bottle of shielding gas) 

The other consideration before you start will be metal thickness assuming you are welding mild steel.  
This will need to be clean bare metal to weld easily. Sand off any paint or rust from your metal where you want to weld before you start. 
If you are trying to set the Mig up to weld some car bodywork then it’s probably safe to say that it’s not going to be very thick. It will probably be between 0.8mm and 1.5mm. 
You are not going to need to set the power or the wire very high otherwise you will be blowing holes in your metal and getting frustrated 


Setting up a Mig welder to find a sweet spot is relatively easy. It’s a balancing act of more power with need more wire speed. The nice fizzy crackle sound is a good start. Start off with a low power and wire speed and test it on a piece of scrap. 
If it just makes a hissing sound then you’ll need to increase your wire speed a touch and test again. A nice fizzy crackle and you are about right. 
If the torch is jumping around and pushing your hand back then you’ve gone too far with the wire speed and need to dial it back a touch. 
Just remember that more thickness in the steel that you’re welding will need more power and more wire but try and find the sweet spot every time. 

Last Considerations

The last consideration will be shielding gas flow. Look on your gas regulator and see if they’ve kindly marked an area on the flow gauge in green to indicate a good setting. 
If you haven’t got any flow gauges then a good tip before you start to weld is to turn on the welder and turn the wire speed to the slowest position. The carefully hold the end of the mig torch near your ear. Make sure you are pointing the end of the torch parallel to your ear and NOT towards it. Pull the torch trigger being careful not to inject yourself with wire and listen to hear any shielding gas flow. You should hear it softly hissing. Too much gas flow will cause problems as will will not enough. 
When you are happy and able to start welding return the wire speed dial to its setting and hold the mig torch so that the end of the shroud is approximately 15mm away from your welding pool. 
One last consideration is to use decent non rusty mig wire. Rusty stuff is your worst enemy and will cause you wire jamming problems and porosity in your weld. Porosity looks like a sponge with lots of little holes in the weld. These are not good and your weld will be weak. 
Look inside your wire feeding case at the two wire drive rollers. You will often see a number stamped onto the sides of one of the rollers. 
It might say 0.6mm or 0.8mm. This refers to the wire diameter that you are using. A small thumb screw on the bottom roller holds it in place. If you are planning to use 0.8mm diameter wire then ensure that 0.8 is facing you on the roller. 
Don’t over tighten the spring lever on the top roller. If the wire is not being driven into the torch when you pull the trigger you will need to slowly increase the pressure between the drive rollers to get it to feed. You should just be able to make it slip by pinching the wire coming out of the torch with your fingers. This is about right for the wire feed roller pressure. Too much force might cause a birds nest in the feeder before it travels into the mig torch.