Flux-core welding settings chart
Starting points by thickness, and — more usefully — what to change when the bead in front of you is wrong.
Starting settings by thickness
| Material thickness | Wire diameter | Typical amperage | Typical arc voltage |
|---|---|---|---|
| 24–20 gauge | 0.030 in | Low end of the machine's range | Around 15–17 V |
| 18–16 gauge | 0.030 in | Roughly 40–70 A | Around 16–18 V |
| 1/8 in | 0.030 in or 0.035 in | Roughly 70–110 A | Around 17–19 V |
| 3/16 in | 0.035 in | Roughly 100–135 A | Around 18–20 V |
| 1/4 in | 0.035 in | Roughly 120–140 A | Around 19–21 V |
Why this chart gives ranges rather than exact numbers
Exact voltage and wire feed speed depend on the machine, the wire brand, the joint type, the position and the stickout. A table claiming to give one correct number for a thickness would be inventing precision it cannot have.
Your machine almost certainly has a settings chart printed inside the wire-spool door covering its own range. That chart, and the wire manufacturer's procedure table, are the authoritative starting points. Use the table above to sanity-check them, not to replace them.
The two controls, and what each one does
Voltage sets the bead shape. Higher voltage spreads the arc, producing a wider and flatter bead. Too high and it spreads thin enough to cut into the parent metal at the edges — undercut. Too low and the bead piles up narrow and tall with poor fusion at the toes.
Wire feed speed sets the current. Feeding wire faster means more wire to melt, which means more current, which means more heat and more penetration. On most machines this is your real heat control.
Because wire speed controls current, the amperage column above is what your machine is producing rather than something you dial in directly. A clamp meter is the only way to know it precisely; for practical purposes, the bead tells you.
Fixing the bead in front of you
This is the table that actually gets used. Change one thing at a time — changing two means you learn nothing from the result.
| Symptom | Most likely cause | What to change |
|---|---|---|
| Excessive spatter | Wrong polarity, voltage too low, or dirty metal | Confirm DCEN first, then clean the metal, then raise voltage slightly |
| Burning through the material | Too much heat or traveling too slowly | Lower wire speed, travel faster, switch to 0.030 in wire, or stitch rather than run a continuous bead |
| Tall, narrow, ropey bead | Voltage too low | Raise voltage a little |
| Undercut grooves along the toes | Voltage too high, or traveling too fast | Lower voltage, slow down |
| Wire pops and burns back to the tip | Wire speed too slow for the voltage | Increase wire speed |
| Wire stubs into the work | Wire speed too fast for the voltage | Decrease wire speed, or raise voltage |
| Bead sits on top, no fusion | Not enough heat, or wrong polarity | Check DCEN, then increase wire speed |
| Slag will not chip off | Voltage too low, or travel too fast | Raise voltage slightly and slow down |
| Porosity (small holes in the bead) | Contaminated metal, or old damp wire | Grind to bright metal; store wire dry and replace rusted spools |
| Arc wanders or feeds inconsistently | Worn contact tip, drive roll tension, or a kinked liner | Replace the tip, check drive tension, straighten the gun lead |
The variables that are not on the dials
Three things change your weld as much as the settings do, and none of them has a control.
Stickout. The wire between the contact tip and the work, typically about three-quarters of an inch for flux-core. Longer stickout preheats the wire and delivers less current to the arc, so drifting mid-weld changes your heat input invisibly. This is the most common reason a bead goes wrong halfway along.
Travel speed. Not a setting, but it determines how much heat goes into each inch of joint. Too fast gives a thin ropey bead with poor fusion; too slow gives excessive build-up and burn-through on thin material.
Gun angle. Drag, at roughly 15 to 20 degrees from vertical, pulling away from the finished weld. Pushing drives slag into the joint — the full beginner's guide covers why.
Wire diameter as a setting
Wire diameter is the setting people forget they have, and on a limited 120-volt machine it matters a great deal.
Thinner 0.030 inch wire needs less current for a stable arc, which makes it the right choice for thin material and for machines with a lower output ceiling. Thicker 0.035 inch wire carries more current and deposits metal faster, which suits thicker material — but it needs amperage the machine may not have.
If you are burning through thin sheet at your machine's lowest settings, changing to 0.030 inch wire is usually the fix. The wire size chart covers the choice in full.
Before you change anything
Three checks that account for most problems people try to solve by adjusting settings:
Is the polarity DCEN? Is the metal ground to bright steel rather than wire-brushed? Is the work clamp attached directly to the workpiece rather than to a bench the workpiece is resting on? Any one of those being wrong makes settings irrelevant.
What we would buy
1. The wire with published procedures
Lincoln Electric Innershield NR-211-MP flux-cored wire
Lincoln publishes full procedure tables, so the starting point is documented rather than guessed.
The single most useful thing about this wire for a beginner is not how it welds, it is that Lincoln publishes procedure data for it. That turns "what should I set?" into a lookup rather than an experiment.
AWS E71T-11, all-position, 0.030 and 0.035 inch, with a published maximum plate thickness of 5/16 inch for 0.045 inch and smaller diameters, run DCEN.
What works
- Lincoln publishes full procedure tables for it, so there is a documented starting setting for every thickness
- All-position rated — it will run a vertical fillet, not just a flat bead
- Available in 1 lb, 5 lb and 10 lb spools, so a small machine does not need a big spool
What does not
- Noticeably more expensive per pound than unbranded E71T-GS wire
- Like every self-shielded wire it produces slag and more spatter than a gas process
2. The machine that makes the chart usable
Forney Easy Weld 261 140 FC-i
Continuous voltage and wire-speed dials, so you can actually land between two settings.
A settings chart is only as useful as your ability to set what it says. On a machine with four fixed voltage taps, a chart telling you to try 17.5 volts is advice you cannot take.
Forney publishes continuous adjustment on both controls, along with a 30% duty cycle at 90 amps and a quarter-inch capacity, which is why it is the machine we recommend most often to people still learning to read a bead.
What works
- 30% duty cycle at 90 A is unusually generous for a 120 V machine in this class
- Infinite voltage and wire-speed control rather than four fixed taps, so you can actually dial a setting in
- 19 lb — genuinely carryable to the job instead of the job coming to it
- No gas bottle, no regulator, no second purchase before your first weld
What does not
- Flux-core only. It will never run gas, so it cannot become your Level 2 machine
- Every weld leaves slag that has to be chipped and wire-brushed off
- Needs a 20 A circuit — a 15 A garage lighting circuit will trip at higher settings
Questions people actually ask
Why is my flux core welding spattering excessively?
The most common cause is wrong polarity — flux-core runs DCEN, electrode negative, and running it electrode positive produces heavy spatter with an unstable arc.
After polarity, check that the metal is ground clean rather than brushed, then try raising the voltage slightly. Some spatter is normal with flux-core; a shower of it is not.
Why is my flux core burning through?
Too much heat into thin material. Lower the wire feed speed, travel faster, and switch to 0.030 inch wire if you are on 0.035.
On genuinely thin sheet, stitch welding — short bursts with a pause between — lets the metal cool and is often the only way to avoid blowing through.
What voltage should I use for 1/8 inch steel?
Typically somewhere around 17 to 19 volts with 0.030 or 0.035 inch wire, but your machine's own door chart is the authority because the usable range depends on the machine.
Set from that chart, run a test bead on scrap of the same thickness, and adjust one control at a time.
Why will my slag not chip off?
Usually voltage too low or travel speed too fast, both of which produce a bead that the slag grips tightly.
A correctly run flux-core bead sheds slag in long pieces with light taps. Slag that has to be fought is a diagnostic signal, not just an annoyance.
Does stickout really change the weld?
Yes, significantly. Wire has electrical resistance, so a longer stickout preheats it more and delivers less current to the arc — effectively turning your heat down without touching a dial.
Holding a consistent stickout is one of the biggest differences between a beginner's bead and a good one.
Sources
Read next
- Flux-core welding for beginners
Drag or push, polarity, reading your first bead, and what to change when it is wrong.
- Welding wire size chart
Which diameter for which thickness, and why the wrong wire looks like a machine fault.
- The best flux-core welders for beginners
Gasless machines that weld the day they arrive, and the duty-cycle figure that separates them.
- Beginner welding mistakes, and how to fix them
Ten causes behind most bad first welds — including the two that look like machine faults.
- Level 1 · Flux-Core: one machine, one wall socket, no gas bottle
If you have never struck an arc, this is your page. One machine, a standard household outlet, and nothing else to buy before your first weld.
Back to Level 1 · Flux-Core, or start over at Find Your Level.
Ryder M.
Ryder M. is the hands-on owner behind Magoo Media Group. He writes Arc & Bead's buying guides and picks every machine on the site. What every recommendation is based on — and what it is not based on — is set out on How We Pick.