MIG settings
GMAW · solid wire (ER70S-6) on mild steel · 75/25 argon–CO₂
Give it a thickness. It gives you a wire size, an amperage, a voltage window and a wire feed speed to start from — then tells you what to change when the bead comes out wrong.
Set the wire speed, not the amps
On a constant-voltage machine there is no amperage knob. You set wire feed speed, and the amperage is whatever the arc draws to burn that wire off at that rate. More wire, more current, more heat. Voltage is a separate control that sets arc length: wind it up and the bead goes flatter and wider, wind it down and it piles up narrow and convex.
So the order is: wire speed for the thickness first, then voltage until the arc sounds right and the bead lies down.
Reading it back
- Tall, ropey, humped bead with poor wash-in — voltage too low for the wire speed. Add a volt at a time.
- Wide flat bead, spatter, arc wandering — voltage too high. Come down, or feed faster.
- Burn-through on thin sheet — drop a wire size before you drop amps; 0.024 in carries far less heat into 18 gauge than 0.035 does.
- Popping and stubbing into the plate — wire speed too high for the voltage, or stickout too long. Keep about 3/8 in of stickout.
Your machine's own chart beats this one. Most MIG sets carry a table inside the door for exactly this, matched to that machine's output. This calculator is built from published Miller and Hobart figures for solid wire on mild steel with C25 gas — change the gas, the wire, or the material and the numbers move.
Not sure whether it worked?
Settings are a hypothesis; the bead is the result. Bead Score photographs a finished bead and scores it — cold lap, spatter, crown height, ripple consistency — and logs the settings that produced it, so next time you're not guessing from a chart at all. Practice feedback, not an inspection.
Sources
- Miller — MIG Welding: Setting the Correct Parameters: 3/16 in with 0.035 wire at 140–175 A, 19–22 V, 240–290 ipm.
- Hobart — parameters for thin materials: 24 ga with 0.024 wire at 13–15 V, 130–160 ipm.
- Miller MIG solid-core weld setting calculator.
- The 1 A per 0.001 in rule for mild steel, which is how the amperage column is derived.