How the Hobby Welder Settings Guide Works
Most hobby welds go wrong at the first setting: too cold and the bead sits on top, too hot and it burns through. This guide gives a sensible place to start for MIG with gas, gasless flux-core and stick on 0.8–10 mm steel (and aluminium on MIG), so your first test bead on scrap is close and you only need small tweaks.
It starts from the old shop rule of about 1 amp per thousandth of an inch of steel (roughly 40 A per mm) for thin work, levels off above about 3–5 mm where hobby machines weld thicker metal in several passes, then adjusts for the joint and position. For stick welding it picks a rod size for the thickness and a current inside that rod's usual range. The MIG wire feed speed to amps calculator covers the opposite question, turning a wire speed you already use into amps.
The Rules Used
1. Amps (MIG and flux-core)
amps ≈ chart(thickness) × joint × position
Chart: 1 mm 45 A, 2 mm 85 A, 3 mm 115 A, 4 mm 135 A, 6 mm 165 A per pass. Fillet × 1.1, lap × 1.05, butt × 1. Horizontal × 0.95, vertical up and overhead × 0.85. Stainless × 0.9.
2. Volts and wire speed
volts ≈ 14 + 0.05 × amps
wire speed (m/min) ≈ amps × in/min per amp × 0.0254
The voltage line is the IEC 60974-1 conventional MIG load voltage, close to a short-circuit arc on argon/CO2; add about 1.5 V for pure CO2. In/min per amp for solid wire: 0.6 mm 3.32, 0.8 mm 1.81, 0.9 mm 1.56, 1.0 mm 1.29.
3. Stick rod and amps
under 1.6 mm → 1.6 rod; 1.6–2.5 → 2.0; 2.5–4 → 2.5; 4–6 → 3.2; over 6 → 3.2 root + 4.0 fill
Typical 6013 ranges: 2.0 mm 40–65 A, 2.5 mm 55–90 A, 3.2 mm 85–130 A, 4.0 mm 120–180 A. 7018 runs a little hotter (2.5 mm 70–100 A, 3.2 mm 100–145 A). The rod box gives the maker's range.
4. Can my machine do it?
duty % at I = rated % × (rated A ÷ I)²
One pass is assumed up to 3 mm for a butt weld from one side and 6 mm for a fillet. Thicker than that needs a bevel and several passes whatever the machine. For more on duty cycle, use the duty cycle calculator.
Worked Example
3 mm mild steel T-joint (fillet), flat, on a 160 A gas MIG rated 20 % at 160 A
- Chart amps for 3 mm: 115 A. Fillet × 1.1 = about 127 A (range about 111–142 A).
- Volts: 14 + 0.05 × 127 = about 20.3 V on argon/CO2.
- 0.8 mm wire: 127 × 1.81 = 230 in/min × 0.0254 = about 5.8 m/min.
- Gas: argon/CO2 at 10–15 L/min. Torch on the positive terminal, 6–10 mm stick-out, push angle.
- Machine: 127 A is inside 160 A. Duty cycle at 127 A ≈ 20 × (160 ÷ 127)² = about 32 %, so roughly 3 minutes of welding in every 10.
Practical Tips
- Listen to the arc. A good short-circuit MIG arc sounds like steady frying bacon. Popping and spitting usually means too little voltage for the wire speed, or too long a stick-out; a hiss with big drops means too much voltage.
- Check polarity when you change wire. Gas MIG runs torch positive; gasless flux-core runs torch negative. Flux-core on the wrong polarity gives a cold, spattery, porous weld.
- Weld on clean steel. Grind back rust, paint and mill scale. Gasless wire tolerates a little dirt; gas MIG does not.
- Outdoors, wind blows away shielding gas. Use flux-core or stick, or build a windbreak.
- Plug and supply: a welder at high amps can draw more than a 13 A plug likes. Check with the workshop power and extension lead calculator.
- More tools: gas cost from the shielding gas calculator, fillet size checks with the fillet weld gauge, preheat for thick or high-carbon steel with the preheat calculator, heat input with the heat input calculator, TIG set-up with the TIG tungsten guide, and rod and wire names in the electrode and wire classification chart.
- Safety. Wear a welding helmet with the right shade, leather gloves and cotton or wool clothes; synthetic fabrics melt. Weld with good ventilation or fume extraction, keep a fire extinguisher handy and check for smouldering for 30 minutes afterwards.
Frequently Asked Questions
About 110–130 A for a butt or fillet weld in the flat, with 0.8 mm wire at around 19–20 V on argon/CO2. A T-joint needs a little more than a butt joint because the heat flows into three directions. Vertical and overhead welds run about 10–15 % cooler. Test on scrap and adjust.
Often yes, but not in one pass. Bevel the edges, leave a small gap, and build the weld up in several runs at amps the machine can hold. A 140–160 A machine can make sound multi-pass welds on 6–10 mm steel if you are patient with the duty cycle. Thickness claims on the box are usually best-case figures.
Gas MIG gives cleaner, neater welds with no slag and is better on thin sheet. Gasless flux-core needs no bottle, works outdoors in a breeze and copes better with slightly dirty steel, but it spatters more, leaves slag to chip off and runs hotter on thin metal. Many hobby machines do both: swap the polarity and the drive roll when you change wire.
6013 is the easy, general-purpose rod: it strikes readily on cheap inverters, works on AC or DC and gives a neat bead, so it is the usual choice for hobby repairs and thin-ish steel. 7018 is a low-hydrogen rod that gives stronger, crack-resistant welds on thicker or structural work, but it must be kept dry and is harder to strike. Most people start with 2.5 mm 6013.
About 10–15 L/min (roughly 20–30 cubic feet per hour) for steel indoors, and 15–20 L/min for aluminium on pure argon. More is not better: too much flow causes turbulence that pulls air into the weld. In a draught, block the wind rather than turning the gas right up.
Stepped (tapped) MIGs set voltage with switches rather than a dial. Enter the machine's minimum and maximum amps and the number of steps, and the guide suggests a step in proportion to the amps you need. Then set the wire speed so the arc sounds smooth, and move one step up or down if the bead is too tall or burns through.
Settings are rule-of-thumb starting points for hobby machines and a first weld on scrap, not a qualified welding procedure. Wire, rods, gas and machines differ; the chart inside your machine and the data on the wire or rod packet take priority. Anything load-bearing or safety-critical (trailers, lifting gear, vehicle structure) should be welded or checked by a qualified welder.