Flux Core Welding Settings Chart: Voltage, Wire & Amps

A fabricator swings the gate open on a farm trailer, looks at the rust-flecked 3/16-inch steel, and realizes there is no gas cylinder on the truck. He reaches for the flux core wire anyway — and with it, a chart he printed from the internet that was wrong in three separate places. That moment is where most flux core frustration starts: the numbers look authoritative, but a flux core welding settings chart is only useful if you know which wire, which polarity, which position, and which power source it was written for.

Why Most Flux Core Settings Charts Mislead You (And What a Good One Must Include)

Picture a shop owner pulling into a customer’s yard with a trailer that needs new steel. No gas cylinder on the truck, no time to chase one, but plenty of 3/16-inch plate and a spool of self-shielded flux core in the bed. Then he pulls out a settings chart printed from a forum post five years ago. Three voltage settings later, the contact tip is burned back into the gun and the bead looks like burnt popcorn with slag crusted over the top.

Nothing was wrong with his welder. The chart was the problem.

So, directly: a flux core welding settings chart is a starting-point table giving voltage, wire feed speed and the resulting amperage for a specific wire diameter, material thickness, joint configuration and welding position. It only works if you identify the wire classification, the polarity and the power source it was written for. Get those three wrong and the rest of the table is decoration.

First, Know Which Flux Core You Actually Have

FCAW (flux-cored arc welding) uses a tubular wire electrode that carries the current, while the flux core inside provides shielding and slag formation. Miller Electric calls it “excellent for welders of all skill levels, especially those who weld outside or on dirty material,” and notes it works much like MIG without the gas bottle.

There are two families, different enough that one chart cannot cover both:

• FCAW-S (self-shielded) creates its own protective atmosphere from the flux core, so no gas is needed. Hobart Brothers notes it is “more forgiving when working with base metal that is somewhat rusty, dirty or otherwise contaminated” for that reason. Common classifications are E71T-11 and E71T-8.
• FCAW-G (gas-shielded) uses the flux mainly for slag control and deoxidizing and needs an external shielding gas, either 100 percent carbon dioxide or an argon/CO2 blend depending on the wire. Hobart Brothers cautions that it “is often used in heavy-duty industrial fabrication and manufacturing and is not typically recommended for beginner and hobbyist applications.”

Both families leave slag on the finished weld that has to be chipped off. That is normal, and it is why flux core results often look less refined than a clean MIG bead.

A Chart Is a Starting Point, Not a Recipe

Even manufacturers treat charts that way. Miller notes that “reference charts are available on your power source to help set the correct voltage and wire feed speed based on the wire diameter and material thickness,” but calls tools like its MIG and flux-cored welding calculator “rough guides from which you can fine-tune your final parameters based on a few test welds.” Hobart Brothers is blunter in its troubleshooting guidance: “Always use the manufacturers recommended parameters for a given wire diameter.”

Remember that last sentence. The chart never outranks the data sheet for the exact spool in your hand.

Why Borrowed Charts Are Worse Than No Chart

A chart from a YouTube video or a generic “MIG vs flux core” article was written for a different wire than the one in your gun. It assumes a wire class you do not have, a polarity you are probably not running and a power source you may not own. The numbers still look plausible on paper, which is what makes them dangerous.

Many of these tables are not flux core charts at all. They are solid-wire MIG tables with a new heading. Three tells give them away:

1. They list DCEP (electrode positive) polarity. Self-shielded T-11 and T-8 run DCEN. A chart demanding reverse polarity is a MIG chart.
2. They never mention slag. If there is no chipping step in the procedure, it is not a flux core procedure.
3. They specify a 3/8-inch stickout. That is a MIG-style extension. Flux core normally runs much longer, roughly 3/4 inch.

What a Good Chart Must Key On

Before you touch a dial, a usable chart must let you identify:

• Material thickness (the row)
• Wire diameter (the column)
• Welding position (flat, horizontal, vertical, overhead)
• Joint configuration (butt, lap, fillet, groove versus fill)

Plus the conditions attached to it: DCEN polarity, a constant-voltage power source and the expected stickout. A chart missing any of those is a poster, not a reference.

One note for anyone working outside the carbon steel range: aluminum is a different story, with dedicated guides to aluminum flux core welding and aluminum MIG welding covering the specialized wire, gun and cleaning requirements. Do not carry a mild steel chart over to aluminum and expect it to hold.

Get this first section right and the rest of the job gets easier, because you now know whether the numbers on the page belong to your wire, your machine and your joint. The next piece breaks down the four numbers that actually drive a flux core arc: voltage, wire feed speed, amperage and polarity.

I’ll rewrite this section, tightening it into the 600–900 word range while keeping all facts and links. Let me check the current length first.

Flux Core Welding Settings Chart for Mild Steel (Printable Reference Table)

Here is the chart most people are actually looking for: one printable table with the voltage, wire feed speed, and expected amperage for common thicknesses of mild steel welded with self-shielded flux core wire. Print it, tape it to the machine, and stop guessing.

Everything below assumes self-shielded E71T-11 / E71T-GS wire on carbon steel, DCEN (straight) polarity, on a constant voltage power source. Gas-shielded wire means different numbers and a different chart. That is not a technicality: a chart written for the wrong wire family is the fastest route to a bead that looks like burnt popcorn.

Table A: Flux Core Welding Settings Chart for Mild Steel

Material Thickness	.024 Wire Voltage / IPM / Amps	.030 Wire Voltage / IPM / Amps	.035 Wire Voltage / IPM / Amps	.045 Wire Voltage / IPM / Amps
1/4 in (14 ga)	—	16.5 V / 169 IPM / 90 A	15.0 V / 150 IPM / 90 A	15.5 V / 79 IPM / 90 A
3/16 in (18 ga)	—	15.0 V / 98 IPM / 60 A	14.3 V / 87 IPM / 60 A	—
1/8 in (16 ga)	—	15.8 V / 126 IPM / 80 A	14.6 V / 98 IPM / 80 A	—
1/10 in (20 ga)	—	14.7 V / 197 IPM / 50 A	—	—
3/32 in (22 ga)	—	—	—	—
24 ga	—	—	—	—

Values are reference starting points for self-shielded E71T-GS wire on mild steel. Amperage is the expected result of the stated wire feed speed on a constant voltage machine, not a separate setting.

Table B: Position Adjustments

Table A is a flat-position baseline. Apply these multipliers once you leave the table.

Welding Position	Adjustment from Flat Settings	Notes
Flat	Baseline (100%)	Start here. Always.
Horizontal	Same, or slightly less (0 to 5%)	Drop the work angle 0 to 15 degrees so the gun points slightly upward to fight gravity.
Vertical up	Minus 10 to 15%	Better penetration on 1/4 inch and thicker. Use a 5 to 15 degree travel angle off vertical with a slight weave.
Vertical down	Minus 10 to 15%	Start at the top, weld down, keep the wire on the leading edge of the puddle on thin material to limit burn-through.
Overhead	Minus 15 to 20%	Smallest wire you can run, minimal weaving, fast travel speed. Hardest position. Avoid it if the job allows.

Those reductions mirror the guidance in Miller’s flux-cored welding basics for mild steel, which advises trimming voltage and amperage by 10 to 15 percent for vertical work and lowering parameters 15 to 20 percent overhead. Hobart Brothers makes the same case for out-of-position work in its guidance on out-of-position welding with MIG and flux-cored processes.

Read This Before You Print It

The manufacturer data sheet always wins. Every flux core wire has a published operating range, and the chart above is a sensible, widely used baseline, not a substitute for the data sheet on your spool. If the two disagree, set your machine from the data sheet, run a coupon, and note the difference. Miller is equally clear that reference charts and its MIG and flux-cored welding calculator are “rough guides from which you can fine-tune your final parameters based on a few test welds.” Hobart Brothers puts it plainly: always use the manufacturer’s recommended parameters for the wire diameter in hand.

Two mill numbers to know. According to Hobart Brothers’ flux core wire guide, “The AWS D1.1 Structural Welding Code for Steel does allow the use of T-11 wires for welding on materials less than 1/2 inch thick.” So on code-controlled structural work, T-11 has a thickness ceiling of 1/2 inch. T-8 wires, by contrast, “offer very good toughness with no thickness restrictions.” Welding 5/8 inch plate with E71T-11 under AWS D1.1 is a compliance problem, not a settings problem.

Row gaps are normal. Some cells are empty because .024 wire is rarely used on this range of material and .045 wire is generally reserved for 1/4 inch and heavier in self-shielded work. An empty cell does not mean any setting goes there. It means the chart does not cover that combination, and you need the data sheet.

Thickness is not the only variable. This chart assumes a butt or fillet joint in mild steel with clean, prepared surfaces. Joint configuration, travel speed, stickout, and position all change effective heat input. Aluminum involves different physics, polarity, and parameters, so start with aluminum flux core welding and aluminum MIG welding rather than adapting these numbers.

Treat the chart as t

Flux Core Welding Settings Chart for Mild Steel (Printable Reference Table)

Here is the chart most people are actually looking for: one printable table with the voltage, wire feed speed, and expected amperage for common thicknesses of mild steel welded with self-shielded flux core wire. Print it, tape it to the machine, and stop guessing.

Everything below assumes self-shielded E71T-11 / E71T-GS wire on carbon steel, DCEN (straight) polarity, on a constant voltage power source. Gas-shielded wire means different numbers and a different chart. That is not a technicality: a chart written for the wrong wire family is the fastest route to a bead that looks like burnt popcorn.

Table A: Flux Core Welding Settings Chart for Mild Steel

Material Thickness	.024 Wire Voltage / IPM / Amps	.030 Wire Voltage / IPM / Amps	.035 Wire Voltage / IPM / Amps	.045 Wire Voltage / IPM / Amps
1/4 in (14 ga)	—	16.5 V / 169 IPM / 90 A	15.0 V / 150 IPM / 90 A	15.5 V / 79 IPM / 90 A
3/16 in (18 ga)	—	15.0 V / 98 IPM / 60 A	14.3 V / 87 IPM / 60 A	—
1/8 in (16 ga)	—	15.8 V / 126 IPM / 80 A	14.6 V / 98 IPM / 80 A	—
1/10 in (20 ga)	—	14.7 V / 197 IPM / 50 A	—	—
3/32 in (22 ga)	—	—	—	—
24 ga	—	—	—	—

Values are reference starting points for self-shielded E71T-GS wire on mild steel. Amperage is the expected result of the stated wire feed speed on a constant voltage machine, not a separate setting.

Table B: Position Adjustments

Table A is a flat-position baseline. Apply these multipliers once you leave the table.

Welding Position	Adjustment from Flat Settings	Notes
Flat	Baseline (100%)	Start here. Always.
Horizontal	Same, or slightly less (0 to 5%)	Drop the work angle 0 to 15 degrees so the gun points slightly upward to fight gravity.
Vertical up	Minus 10 to 15%	Better penetration on 1/4 inch and thicker. Use a 5 to 15 degree travel angle off vertical with a slight weave.
Vertical down	Minus 10 to 15%	Start at the top, weld down, keep the wire on the leading edge of the puddle on thin material to limit burn-through.
Overhead	Minus 15 to 20%	Smallest wire you can run, minimal weaving, fast travel speed. Hardest position. Avoid it if the job allows.

Those reductions mirror the guidance in Miller’s flux-cored welding basics for mild steel, which advises trimming voltage and amperage by 10 to 15 percent for vertical work and lowering parameters 15 to 20 percent overhead. Hobart Brothers makes the same case for out-of-position work in its guidance on out-of-position welding with MIG and flux-cored processes.

Read This Before You Print It

The manufacturer data sheet always wins. Every flux core wire has a published operating range, and the chart above is a sensible, widely used baseline, not a substitute for the data sheet on your spool. If the two disagree, set your machine from the data sheet, run a coupon, and note the difference. Miller is equally clear that reference charts and its MIG and flux-cored welding calculator are “rough guides from which you can fine-tune your final parameters based on a few test welds.” Hobart Brothers puts it plainly: always use the manufacturer’s recommended parameters for the wire diameter in hand.

Two mill numbers to know. According to Hobart Brothers’ flux core wire guide, “The AWS D1.1 Structural Welding Code for Steel does allow the use of T-11 wires for welding on materials less than 1/2 inch thick.” So on code-controlled structural work, T-11 has a thickness ceiling of 1/2 inch. T-8 wires, by contrast, “offer very good toughness with no thickness restrictions.” Welding 5/8 inch plate with E71T-11 under AWS D1.1 is a compliance problem, not a settings problem.

Row gaps are normal. Some cells are empty because .024 wire is rarely used on this range of material and .045 wire is generally reserved for 1/4 inch and heavier in self-shielded work. An empty cell does not mean any setting goes there. It means the chart does not cover that combination, and you need the data sheet.

Thickness is not the only variable. This chart assumes a butt or fillet joint in mild steel with clean, prepared surfaces. Joint configuration, travel speed, stickout, and position all change effective heat input. Aluminum involves different physics, polarity, and parameters, so start with aluminum flux core welding and aluminum MIG welding rather than adapting these numbers.

Treat the chart as the start of the job, not the end of it. Set it, run a short coupon on the same joint and thickness, chip the slag, and look at the bead before you commit to a production run. A chart gets you to the first weld; the coupon gets you to the good weld.

Self-Shielded vs Gas-Shielded Flux Core: Which Settings Chart Applies to You

Search for a flux core welding settings chart and nearly every result is a self-shielded table. That is fine, since self-shielded wire is by far the most common in the field. It becomes a problem the moment you hold a spool of E71T-GS or a T-9 wire and dial in numbers that were never tested with an external shielding gas. Those numbers are not a little off. They produce a rough, wide, spattery bead and puzzled shop talk.

So before you touch a knob, answer one question: is this wire making its own atmosphere, or is a cylinder feeding it?

Two processes, two charts

Self-shielded FCAW (FCAW-S) burns a tubular wire whose flux core decomposes as it melts, generating its own protective atmosphere around the arc. No cylinder, no regulator, no hose to trip over. That is why self-shielded wire dominates farm work, structural fabrication and field repair.

Gas-shielded FCAW (FCAW-G) uses the flux mainly for slag formation and deoxidizing rather than for atmosphere. The shielding comes from a bottle: either 100 percent carbon dioxide or a 75 to 85 percent argon/carbon dioxide blend, depending on the wire and the welding characteristics you want. As Hobart Brothers puts it, FCAW-G wires are similar in construction to self-shielded FCAW-S wires, “but do not generate enough of an inert atmosphere during welding to fully protect the weld.” Add gas and those same wires run far easier, with a steadier arc and a better bead appearance. Hobart’s verdict is blunt: FCAW-G offers much greater usability than FCAW-S. Planning to run bottles? Our guide to gases, cylinders and safety covers the hardware side.

Feature	FCAW-S (self-shielded)	FCAW-G (gas-shielded)
Shielding	Made by the flux core, no gas needed	External gas: 100% CO2 or 75-85% Ar/CO2
Common classifications	E71T-11, E71T-8	E71T-1, E71T-9, E71T-12, E71T-5
Polarity	DCEN (straight polarity)	Check the data sheet; many run DCEP, some T-5 run DCEN
AWS specification	A5.20 carbon steel, A5.29 low-alloy	A5.20 carbon steel, A5.29 low-alloy
Settings chart	Widely published online	Use the manufacturer data sheet

The gas-shielded families: T-1, T-9, T-12 and T-5

Most steel FCAW-G wires fall under one of two AWS specifications: AWS A5.20 for carbon steel FCAW electrodes, or AWS A5.29 for low-alloy. Low-alloy and high-strength filler metals deserve their own reading; our alloy steel welding electrode guide goes deeper.

The number after the T is the usability designator, and each one carries a different slag type and a different toughness promise.

• T-1 (rutile slag). The baseline gas-shielded carbon steel wire. Minimum impact toughness of 20 ft-lbs at 0 degrees F. Widely available, forgiving to run, and the safe default when no code requirement pushes you elsewhere.
• T-9 (rutile slag). Same chemical composition requirements as T-1, but with more stringent toughness requirements:20 ft-lbs at -20 degrees F minimum. Hobart calls T-9 “the most common in the industry,” and it is the workhorse for structural and pressure work.
• T-12 (rutile slag). Matches T-9 toughness but with restricted tensile strength (70 to 90 ksi versus 70 to 95) and tighter manganese windows (1.60 versus 1.75). Developed for ASME BPVC WPS applications to reduce cracking risk from poor ductility in thick material. Maximum diffusible hydrogen is often 8.0 ml/100g, sometimes as low as 4.0 ml/100g.
• T-5 (basic slag). The toughness and penetration champion. Basic-slag wires give the best toughness among FCAW-G classifications, contribute very little oxygen (above a very low 300 ppm level is detrimental), deliver high arc force that assists penetration, and produce low diffusible hydrogen. The trade: more globular transfer, a harsher arc, increased spatter and a more convex bead with solidification lines. Many T-5 wires are limited to flat and horizontal positions, and some are formulated for DCEN. Always read the data sheet.

Self-shielded: T-11 versus T-8

Staying with FCAW-S? You really have two choices.

E71T-11 is the forgiving one. It has a wide operating parameter window, tolerates technique error better than most flux core wires, and is the standard all-position self-shielded wire. In exchange, it carries no toughness requirement and is less crack resistant, so it is not the wire for demanding or heavily restrained joints. Our all-position welding rod guide shows where these sit in the wider filler metal picture.

E71T-8 is the tougher, heavier-duty option. It must meet 20 foot-pounds at -20 degrees Fahrenheit, and the “J” designator raises that to 20 foot-pounds at -40 degrees. T-8 wires are often approved for Demand Critical Welds under AWS D1.8/D1.8M, qualified either with a “D” designator on the classification (for example E71T-8JD H8) or via Annex A qualification. The catch is that T-8 runs hot, lays down heavy slag, and takes more skill to control. One practical detail: the smallest T-8 diameter usually sold is 1/16 inch, because T-8 has a higher powder fill percentage than T-11.

One last point on why gas-shielded charts look different. With an external gas, the same voltage produces a different arc, and the wire feed speed needed to reach a given amperage shifts with it. That is why a gas-shielded table is narrower in scope: thickness, wire diameter, position and gas, and little else. Dialing in a gas-shielded machine from scratch? Start from the spool data sheet, then sanity-check the result against Miller’s flux-cored welding basics for mild steel and the Miller MIG and flux-cored welding calculator.

Adjusting the Chart for Welding Position: Flat, Horizontal, Vertical and Overhead

Most people miss one thing about a flux core welding settings chart: the numbers were almost certainly measured flat. Tip the gun sideways against a trailer frame and every one of them is already expired. Position failures are the quiet reason welders blame the chart itself. The metal was simply in a different attitude than the chart was written for.

Flat and Horizontal: A Small Nudge, Not a New Chart

Flat position is where the chart comes from: the work sits flat, the puddle spreads out in front of you, and the job is mostly heat control.

Horizontal fillets differ in one important way. Gravity pulls the puddle toward the bottom of the joint, so point the gun slightly upward to push molten metal back into the corner. That means dropping the work angle 0 to 15 degrees from the vertical you would use flat. Miller’s guide to flux-cored welding for mild steel puts it plainly: voltage and amperage settings for flux-cored welding in the horizontal position are usually the same or slightly less than flat. Run 15 volts and 100 amps flat and horizontal might want 15 volts and 90 amps. Do not go hunting for a dramatic change.

Work angle references from Miller:

• Flat butt weld: hold the gun at a 90 degree work angle.
• Flat T-joint fillet: position the gun at a 45 degree angle.
• Lap joint: angle the gun between 60 and 70 degrees.

Horizontal is where most welders cut their teeth, because a fillet weld is easy to read and inspect. The all position welding rod guide covers the stick consumables side if you want to compare processes on the same joint.

Vertical: Drop Everything 10 to 15 Percent

Vertical is where beginners get frustrated and where the chart needs the most deliberate adjustment. Miller advises that since you are fighting gravity, consider reducing voltage and amperage 10 to 15 percent from the settings for the same weld in flat position. A flat setting of 15 volts and 90 amps becomes roughly 13 volts and 78 amps vertical. That lower heat input keeps the puddle small enough to stay where you put it instead of running down the plate.

Within vertical you have two more choices:

Vertical down

Start at the top and work downward, using a slight weave to distribute heat along the joint. On thin material keep the wire on the leading edge of the puddle to limit burn-through. Vertical down gives shallower penetration, but it is easier on the welder and faster on thin material.

Vertical up

Travel angle drops 5 to 15 degrees from perpendicular, with a slight weave. Vertical up gives noticeably better penetration on thicker material, typically 1/4 inch and up, because the arc is directed down into the joint and the puddle is pushed up under the gun. It is harder to control and punishes excessive heat input. This is also where flux core slag fights you hardest, so keep travel speed honest and chip slag between passes instead of laying a second pass over loose slag.

Overhead: Smallest Wire, Lower Numbers, Fast Travel

Overhead is the hardest position in welding, and Miller’s guidance is to avoid it when possible. When you cannot avoid it, the recommendations are specific: use the smallest wire possible, lower your welding parameters by 15 to 20 percent, keep weaving to a minimum and maintain a fast travel speed. Overhead is not where you build a big, beautiful bead. It is where you put down a consistent string of small beads without melting the joint or dropping a shower of slag on your helmet.

Drag Angle vs Travel Angle: The Two Angles Everyone Mixes Up

Two angles control the torch, and confusing them is a reliable way to wreck a bead. The work angle is how the torch is tilted relative to the work surface, side to side: the 90 degree butt, 45 degree fillet and 60 to 70 degree lap reference above. The travel angle is how far the torch is pushed forward in the direction of travel. Miller states that normal welding conditions in all positions call for a travel angle of 5 to 15 degrees, and that travel angles beyond 20 to 25 degrees can lead to more spatter, less penetration and general arc instability.

The drag angle is the travel angle you use when you pull the torch instead of pushing it. Hobart Brothers lays out the ranges: in flat, horizontal and overhead positions your drag angle should be between 15 and 45 degrees, and in vertical up it should be between 5 and 15 degrees.

Why Position Matters More for Flux Core Than for MIG

Two things separate FCAW from solid-wire MIG out of position. First, flux core runs higher heat input for the same amperage than MIG, because the flux adds heat to the arc and the extra slag layer insulates the puddle. More heat means a bigger puddle, and a bigger puddle in vertical or overhead means more sag, more burn-through and more time fighting the metal.

Second, slag has weight and it clings. Flux under the puddle acts as a small dam that tends to slump in vertical up and can fall onto the plate, into the puddle, or onto your helmet in overhead. That is exactly why the drag technique and position-specific voltage reductions matter more here than on a clean MIG bead. Hobart’s discussion of out-of-position welding covers the comparison in more detail.

Position is not a footnote to the chart. It is one of the four variables the chart is keyed on, which is exactly why a chart listing only flat-position numbers for every weld fails the first time you point the gun at a vertical joint.

Gun Setup That Makes the Chart Work: Drive Rolls, Liner, Contact Tip and Stickout

A settings chart can be perfect and the weld still comes out wrong. Every number on a flux core welding settings chart assumes a specific gun setup: the right drive rolls, the right liner, a clean contact tip and a measured stickout. Change any of those and the numbers stop meaning what the chart says, which is why so many flux core trouble spots surface as wire feed faults first: birdnesting, where wire tangles inside the gun, and burnback, where the weld forms inside the contact tip.

Drive Rolls: The One Part You Must Not Get Wrong

Flux core wire is a tubular consumable, so grip matters. As Hobart Brothers puts it, FCAW wire is much softer than GMAW solid wire, and the correct drive rolls are knurled V-groove rolls: the V cradles the round wire while the knurling gives bite, so the roll pushes without squashing it. Solid-wire rolls built for ER70S-6 will flatten a .030 or .045 flux core wire the first time you run it. Miller makes the same point in its flux-cored welding basics guide: knurled drive rolls bite the wire without compressing and deforming it.

Setting Drive Roll Tension

Tension is a procedure, not a number. Hobart Brothers gives the method: release the drive roll tension, then increase it while feeding wire into the palm of your welding glove, going one half turn past wire slippage. That extra half turn matters because feed pressure fluctuates as the torch moves. Too much tension is the other failure: Hobart warns it flattens the wire and stops it feeding through the contact tip, and the symptom is a gun that pushes wire but the wire stops at the tip, or stutters and chatters.

Liner: The Cheap Part That Causes Expensive Problems

The liner is the tube inside the gun cable that guides wire from the feeder to the gun. It has to match the wire diameter and be clean.

• Right size. Match the bore to the wire diameter. Too large lets the wire wander and buckle, too small restricts it.
• Trim on schedule. Cut back the liner and gun wire guide as the manufacturer specifies, and re-check after any wire or tip change.
• Burrs kill feed. A burr on the liner edge or wire guide snags soft wire and starts a birdnest right at the gun.
• Too short is bad too. Unsupported wire whips and tangles.
• Blocked liners get replaced, not cleaned. Once flux and wire dust pack the tube, swap it out. Wire that has birdnested once is usually damaged, so pull it out, cut off the kinked section, re-thread and check the liner.

Burnback and Wire Extension

Burnback means the weld forms inside the contact tip instead of at the workpiece, and the tip starts to melt. It is almost always a wire feed speed problem, a gun distance problem, or both. Hobart Brothers says to increase the wire feed speed and the distance of the gun from the workpiece, keep the contact tip no further than 1-1/4 inches from the metal, and replace the contact tip if burnback occurs, because a burned back tip is deformed and a deformed tip changes wire speed and the arc.

Wire extension is the flip side. Hobart states the wire should extend no more than 1-1/4 inches beyond the contact tip, and that is a ceiling rather than a target. Long extension on soft tubular wire means the wire drags on the work, wanders and tangles, and makes the arc behave unpredictably.

Stickout: The Number Most People Guess Wrong

Stickout is the length of wire sticking out past the contact tip, and flux core wants more of it than MIG does. Miller’s guidance: generally, flux-cored welding requires a stickout of around 3/4 inch, about twice the recommended stickout for MIG welding. Hobart Brothers breaks it down by wire class: T-11 gets a 1/2- to 3/4-inch stickout with a 10 to 20 degree drag angle, while T-8 gets 1 inch to 1-1/4 inch depending on wire diameter.

Wire	Stickout	Drag angle
E71T-11 (self-shielded)	1/2 to 3/4 in	10 to 20 degrees
E71T-8 (self-shielded)	1 to 1-1/4 in	As wire diameter requires
General flux core rule	About 3/4 in	Always drag, never push

Longer stickout preheats the wire before it hits the arc, which raises deposition rate and improves penetration on thicker material. Too much stickout reduces the arc’s ability to push the puddle and increases spatter and worm tracking. Miller’s MIG and flux-cored welding calculator is a good sanity check for the numbers you land on, but stickout still gets set by hand on the gun.

Power Source, Leads and Ground Clamp

Before blaming the chart, confirm the machine runs constant voltage rather than constant current, and that polarity is DCEN for self-shielded T-11 and T-8. A constant current source makes the arc hunt and the weld inconsistent. Check the gun cable and work lead connections for looseness or damage, and make sure the ground clamp bites bare, clean metal, because poor ground contact shows up as arc wandering, chatter and spatter that look like voltage problems. On job sites a suitcase wire feeder keeps the wire feed and power source in one transportable unit. If you think in bench machine terms, the aluminum flux core welding guide covers the same gun-side logic for another metal.

Storing the Wire and the Pre-Weld Checklist

Moisture is the enemy of a good bead. Hobart Brothers states storage temperature should ideally be between 40 and 120 degrees Fahrenheit with a maximum humidity of 80 percent, and the wire should stay in its original packaging in a dry enclosed area, off a damp concrete floor. Wet wire produces worm tracking, and plenty of welders blame the chart and lower voltage when the real cause is moisture.

• Knurled V-groove drive rolls sized for the wire
• Tension set by the glove method, half turn past slippage
• Liner right size, trimmed, burr-free; tip clean, no burnback damage
• Stickout about 3/4 in; 1/2 to 3/4 in for T-11, 1 to 1-1/4 in for T-8; extension no more than 1-1/4 in past the tip
• Constant voltage source, DCEN polarity, ground clamp on clean bare metal, wire dry and stored 40 to 120 F

Two minutes with this list before you light the arc turns every wire feed problem from a mystery into a checklist item, so when you do adjust voltage or wire feed speed, you are adjusting a chart instead of chasing a mechanical fault.

Reading the Bead: Troubleshooting Charts, Burnt Edges and Porosity

A chart gets you to a decent starting point, but it will never read the puddle for you. With self-shielded flux core, real verification comes from chipping slag off a test coupon and reading the bead. Treat every new spool of wire, position change, or material switch as its own excuse to test weld.

Feeding Issues: Birdnesting and Burnback

Nothing kills momentum faster than the wire locking up. Per Hobart Brothers, birdnesting is a tangle of wire that stops the feed, most often caused by incorrect drive roll tension, blocks in the liner, an improperly trimmed liner, the wrong liner size, or the wrong drive rolls. Because tubular flux core wire is much softer than solid wire, the culprit is almost always mechanical. Flip up the drive rolls, pull the damaged wire back, trim off the crushed section, and re-thread. If it repeats, confirm you are running knurled V-groove drive rolls rather than solid wire rolls and inspect the liner for burrs or blockage.

Burnback is the opposite problem, where the arc welds itself into the contact tip. It is typically caused by wire feed speed (WFS) being too slow for your voltage, or by holding the gun too close to the workpiece. Raise WFS slightly, hold proper stickout, and replace any melted contact tips. A tip starting to ball up will only make this worse, so swap it early. These failures show up on every flux core job, mild steel or niche setups like aluminum flux core welding.

Gas, Slag, and Surface Defects

With self-shielded flux core, the shielding gas comes from the flux itself. That is the process’s biggest perk and the root of several specific defects.

Porosity shows up as tiny gas pockets throughout the weld and, per Hobart Brothers, will significantly weaken the structural integrity of your weld. The most common causes are a dirty workpiece (rust, grease, paint, oil, moisture), wire extending too far past the contact tip, and sulfur or phosphorus in the base metal. Clean down to bright metal before striking an arc. That prep matters as much here as it does on processes that demand pristine surfaces, like those covered in our guide for aluminum cleaner for welding.

Worm tracking are the worm-like, raised marks that crawl along your bead, caused by flux gases when voltage is excessive for a given wire feed speed and amperage. Drop voltage in increments of one-half volt until the marks vanish. Change voltage only for this issue; jumping your WFS wildly to compensate will throw your amperage out of balance.

Slag inclusions are pockets of solidified flux trapped under the weld metal. Slag is natural to flux core, inclusions are not. Causes include incorrect bead placement, incorrect travel angle, low heat input, and poor interpass cleaning. Increase your drag angle and raise voltage until the inclusions cease. Most important of all, chip your slag between every pass, since leaving old slag behind is one of the quickest ways to trap it under a fresh bead.

Fusion and Penetration Problems

Once feeding and slag are under control, confirm the puddle is actually bonding to the base metal. These defects are almost always heat input related.

Undercutting is a groove melted into the base metal at the toes of the weld. Correct it by reducing welding current, decreasing welding arc voltage, adjusting electrode angle as needed, and reducing travel speed so weld metal completely fills the melted-out area. It usually comes from traveling far too fast while running hot.

Incomplete fusion occurs when weld metal fails to bond with the base metal or a previous pass. Causes include electrode or work angles letting metal run ahead of the arc, dirty metal, or insufficient heat input. Keep the puddle in front of your travel, raise current to add heat, and ensure the joint is spotless. On thicker material, poor prep will trump your chart values every time.

Excessive penetration is the puddle blowing through the backside more than desired: select a lower voltage range, reduce wire feed speed, and increase travel speed. Lack of penetration is the opposite, with fusion only at the surface: raise wire feed speed, raise the voltage range, and/or reduce travel speed. Recheck joint prep as well, especially over 1/4 inch, because an un-beveled butt joint is nearly impossible to fully penetrate in a single pass.

Bead Appearance	Likely Cause	Knob To Turn
Tangled wire, gun locks up	Birdnesting (drive rolls, liner, tension)	Fix tension, knurled rolls, inspect liner
Wire melts into contact tip	Burnback (low WFS, gun too close)	Raise WFS, add stickout, replace tip
Pinholes through bead	Porosity (dirty metal, long stickout)	Clean to bright metal, shorten stickout
Worm-like surface marks	Worm tracking (excess voltage)	Voltage down in 1/2 volt steps
Slag trapped under bead	Inclusions (bad angle, low heat)	More drag angle, more voltage, chip passes
Groove at weld toes	Undercutting (too hot and fast)	Lower current/voltage, slow travel
Cold bead, poor bond	Incomplete fusion (puddle ahead)	Puddle in front, raise current, clean metal
Blowthrough on backside	Excessive penetration (too much heat)	Lower voltage and WFS, speed up travel
No root fusion, ropey bead	Lack of penetration (low heat/prep)	Raise WFS and voltage, bevel over 1/4 inch

Your chart is a first guess, not a verdict. The more you read your own beads, the less time you spend fighting burnt edges, burnback, and porosity. Your setup will vary from shop to shop depending on leads, feeder, and supplies from vendors such as Airgas welding supplies, but the bead never lies. Refer back to Miller’s flux-cored basics for power source specifics, and let your coupon have the final say over any internet chart.

Seven Mistakes That Ruin Flux Core Welds (And How to Avoid Each One)

Even with the perfect flux core welding settings chart in hand, one small oversight can turn a promising bead into a mess of spatter, porosity, or lack of fusion. These failures rarely come from the machine but from setup and technique errors you can fix today. Here are the seven most common mistakes, plus an eighth that ties them all together.

1. Running the Wrong Polarity (DCEP Instead of DCEN)

The fastest way to ruin a self-shielded flux core weld is to leave the polarity set for solid wire. Most solid MIG wire runs on DCEP (Direct Current Electrode Positive), but self-shielded wires such as E71T-11 and E71T-8 need DCEN (Direct Current Electrode Negative).

As Hobart Brothers explains, “using the incorrect polarity can result in poor welding performance, including increased spatter levels.” Spatter the instant you strike an arc? Check polarity before touching any other dial.

2. Using a Constant Current (CC) Power Source

Flux core wire was designed to run on a constant voltage (CV) source, not a constant current (CC) machine. CC sources suit stick welding fine, but they play badly with tubular wire.

Hobart Brothers warns that “The power received from a CC power source fluctuates too much when using these wires, and can cause inconsistent quality and weld defects such as porosity.” If CC is all you own, look into a CV-capable machine before running self-shielded wire on anything structural.

3. Using Solid-Wire Drive Rolls on Tubular Wire

Tubular flux core wire is far softer than solid GMAW wire and cannot take the same abuse from the drive system. Standard V-groove solid-wire rolls flatten the wire, trap it at the contact tip, and almost guarantee birdnesting.

Per Hobart Brothers, “FCAW wire is a tubular consumable and therefore is much softer then GMAW solid wire. The correct drive rolls for FCAW wire are knurled V groove drive rolls.” Swapping to knurled rolls is cheap and one of the highest-return fixes on this list.

4. Borrowing a MIG Settings Chart

Not all “flux core” charts are equal. Plenty are relabeled MIG tables. The processes look similar but behave differently: MIG runs on DCEP, uses a much tighter stickout, produces no slag, and needs a different wire feed speed at the same amperage. Dialing in self-shielded wire with MIG numbers starts you from the wrong baseline. Our MIG vs flux core guide breaks down the differences.

5. Ignoring Stickout

Stickout is the most overlooked variable in flux core, and it is critical. Aim for roughly 3/4 inch of wire extension beyond the contact tip with T-11. T-8 wants a longer stickout, about 1 to 1-1/4 inches, and larger wire diameters need more still. Too close and you risk burnback. Too far and the flux loses its shielding, which brings back porosity.

6. Beveling Nothing on Thick Plate

A square butt is fine for thin sheet. Thicker material needs a bevel. Miller recommends that “For material over 1/4 inch, it’s usually a good idea to bevel the edges of the base materials to ensure complete fusion of the two parts.” Hobart Brothers adds that “in addition to increasing the current and slowing travel speeds, a beveled joint can greatly reduce the chance of incomplete penetration.” Skip it on 1/4 inch plate and up and you weld a weak, shallow joint.

7. Welding Vertical or Overhead With Flat Settings

Gravity does not care what your chart says. Miller advises you to “consider reducing the voltage and amperage 10 to 15 percent from the settings for the same weld in the flat position” when welding vertical. For overhead work, drop them further, roughly 15 to 20 percent. Force flat-position heat into an out-of-position joint and you get puddle sag, undercut, and an uncontrollable bead.

Welding position	Voltage and amperage vs. flat settings
Horizontal	Baseline chart values
Vertical	Reduce 10 to 15 percent
Overhead	Reduce 15 to 20 percent

8. Not Test-Welding the Chart Values or Reading the Bead

The biggest mistake is treating the numbers as gospel. Hobart Brothers puts it plainly: “Always use the manufactures recommended parameters for a given wire diameter.” That means reading the wire classification on the spool label and working from the manufacturer data sheet rather than any random internet chart. Then run a test coupon on the same thickness and joint as the job, chip the slag, inspect fusion, and adjust.

A settings chart gets you to your first weld. Your coupon gets you to a sound, production-ready one. Avoid these mistakes, read your bead, and you will save yourself a mountain of frustration in the shop.

Safety, Fume Control and the Code Rules That Govern Flux Core Work

A perfect settings chart can still get a welder hurt. Voltage, wire feed speed and amperage shape the bead; they say nothing about arc light burning through your retina or hexavalent chromium in your lungs. The parts of flux core welding charts skip carry legal weight.

Start with PPE. Miller’s field guidance for flux core calls for leather shoes or boots, cuffless full-length pants, a flame-resistant long-sleeve jacket, leather gloves, a welding helmet, safety glasses and a bandana or skull cap, plus clearing the area of anything that burns. Cuffed trouser legs catch slag and smolder, turning a glob of flux into a burn an hour later. The glasses under the helmet matter: flux core arcs throw sparks in every direction. The Miller flux core basics guide has the current PPE list.

Eye Protection and Helmet Shade Selection

Federal law is not flexible here. 29 CFR 1910.252(b)(2)(i)(A) states that “helmets or hand shields shall be used during all arc welding or arc cutting operations.” No exceptions for a quick tack.

The shade guide in 1910.252(b)(2)(ii) lists shade 12 for gas-shielded arc welding of ferrous metals and shade 10 for shielded metal-arc welding with 1/16- to 5/32-inch electrodes. Flux core arcs are brighter, so many operators land on shade 12 to 13. A shade that feels too dark indoors may still be too dark in the sun, and dust and grinding grit scratch the lens until it scatters light into your eyes.

Ventilation: The Requirement Everyone Underestimates

OSHA spells the duty out plainly. 29 CFR 1910.252(c)(1)(iii) requires that “local exhaust or general ventilating systems shall be provided and arranged to keep toxic fumes, gases, or dusts below the maximum allowable concentration” set out in 29 CFR 1910.1000, the air contaminants table.

Paperwork matters too. 1910.252(c)(1)(iv) requires hazardous materials in fluxes and filler metals to be covered by the employer’s Hazard Communication program: safety data sheets, labels, training and a written program. And 1910.252(c)(1)(v)(B) requires filler metal containers to carry the notice “Do not use in areas without adequate ventilation. See ANSI Z49.1 … published by the American Welding Society.”

That label is not decorative. A trailer with no cross-ventilation or a tank welded on a winter day is a fume trap. Fix it with a fume extractor hose near the arc or a fan pulling air through the work area. A respirator is a last resort.

Hexavalent Chromium: The One to Take Seriously

Stainless and some nickel alloys contain chromium, and welding them can generate hexavalent chromium, Cr(VI), a confirmed human carcinogen. 29 CFR 1910.1026 sets the permissible exposure limit at 5 micrograms per cubic meter as an 8-hour time-weighted average, with an action level of 2.5. NIOSH and ACGIH recommend a far stricter 0.2 micrograms per cubic meter. OSHA’s own fact sheet FS-3647 on welding hazards puts it plainly: Cr(VI) fume “is highly toxic and can damage the eyes, skin, nose, throat, and lungs and cause cancer.”

Here is the surprise: shielded metal arc and flux core arc welding often generate higher Cr(VI) levels than TIG or GMAW. Flux core is not the clean process for stainless. Shielding gas and fume extraction, not the process name, control exposure, and flux core on stainless still means local exhaust and a Hazard Communication program that names the filler metal hazards.

Fire Prevention and the 35-Foot Rule

Flux core produces more slag than MIG. Hot slag rolls off the bead, glows and burns through whatever it lands on. 29 CFR 1910.252(a)(1)(i) and (a)(2)(vii) call for movable fire hazards to be moved to a safe place and for combustibles to be relocated at least 35 feet (10.7 m) from the work site where practicable.

When you cannot clear the combustibles, 1910.252(a)(2)(iii)(B) requires that “a fire watch shall be maintained for at least a half hour after completion of welding or cutting operations.” Half an hour, not five minutes: a designated person, a working extinguisher and quick access to the work area.

Confined Spaces and the Rules That Go With Them

Inside a tank, vessel, pipe or hopper, ventilation is a prerequisite to entry. The power source and cylinders stay outside, leads run in through the manway with a spotter, cylinders are secured upright, and an attendant stays at the entry while a portable extraction duct goes inside. The space is monitored for oxygen and toxic gases, and untrained, untested or unpermitted space means no.

Every rule here applies to flux core. Self-shielded wire adds one bonus in tight quarters: no cylinder feeding the torch, which is why flux core is so popular in field and confined work. The fume rules still apply at full force.

One last housekeeping item: clean slag off the table between joints, keep loose gloves away from a hot end, and check the spool for moisture before wiring it up. Damp flux core produces worm tracking, and a spool that sat in a damp truck is a fume and quality problem. More on storage in our guide to flux core wire and shielding setups.

A Repeatable Workflow for Dialing In Any Flux Core Job

A settings chart gives you a number. A process is what makes that number repeatable next Tuesday, on a different trailer, with a different spool. This sequence costs about ten minutes up front and saves hours at the back end.

1. Read the spool, then pull the data sheet. Confirm the AWS classification (E71T-11, E71T-8, and so on) and the wire diameter first. The manufacturer’s data sheet outranks any table online, including the one in this article. Gas-shielded wire also means the right cylinder and mix, worth sorting out in advance: the Air Gas Welding Supply guide to gases, cylinders and safety covers it.
2. Confirm polarity and power source. Self-shielded T-11 and T-8 run DCEN (straight polarity), the reverse of most solid wire, and they need a constant voltage (CV) source, not constant current. A CC-only machine is the wrong tool. Wondering why a stick set-up behaves differently? Why SMAW still wins on certain work is a useful comparison.
3. Verify the gun hardware. Knurled V-groove drive rolls, a liner sized for the electrode, and a clean contact tip. The Airgas welding equipment guide lists the parts worth checking.
4. Measure the material and pick the row. Use a thickness gauge rather than eyeballing it. On a groove weld with plate over 1/4 inch, bevel the edge now rather than fight fit-up later.
5. Set the numbers. Use the chart, the power source’s reference chart, or Miller’s MIG/Flux-Cored Weld Setting Calculator. Set the voltage, dial in the wire feed speed, then read the resulting amperage on the machine’s display.
6. Adjust for position. Horizontal is the same as flat or slightly less. Vertical runs 10 to 15 percent below flat, overhead 15 to 20 percent below flat. On drag angle, Hobart Brothers advises 15 to 45 degrees in flat, horizontal and overhead, and 5 to 15 degrees vertical up. Product-specific position rules sit in the all-position welding rod guide.
7. Set stickout. Roughly 3/4 inch for most flux core work: 1/2 to 3/4 inch for T-11, and 1 to 1-1/4 inches for T-8, which needs the longer extension because of its higher powder fill.
8. Run a coupon. Same joint, same thickness, short length. Chip the slag and check bead profile, sidewall fusion and soundness. On T-8, chip often, because Hobart notes these wires produce “a very heavy slag that can interfere with the welding arc. This can prevent the weld bead from wetting out properly.”
9. Change one variable at a time and write it down. Log the final numbers on the job folder, the truck door, or your phone. Next time the same wire and thickness come up, you start where you left off.
10. Weld production in passes. On groove welds, run fill and cap passes and chip the slag between them. Never let slag roll into the next pass.

Why the Routine Beats the Chart

Manufacturers are blunt about it. Miller calls its charts and calculators “rough guides from which you can fine-tune your final parameters based on a few test welds.” Hobart Brothers puts it more plainly: “Quality self-shielded FCA welds are the result of good welding technique, the proper choice of parameters and the welder’s ability to identify a problem quickly and rectify it.” That last clause is the part no chart can do for you.

Hobart’s guidance is also to “realize advantages with proper training,” because “welding operator training and proper certification are essential.” A repeatable workflow builds that eye fast: same sequence, every job.

Printable Job Checklist

• Spool label read: classification and diameter confirmed
• Manufacturer data sheet on hand
• DCEN polarity and CV power source confirmed
• Knurled V-groove drive rolls, correct liner, clean contact tip
• Thickness measured with a gauge; chart row selected
• Voltage set, wire feed speed dialled in, amperage verified on the display
• Position and stickout adjustments applied
• Test coupon welded, slag chipped, bead inspected
• One variable at a time; final settings recorded
• Groove welds: bevel over 1/4 inch, fill and cap passes, slag chipped between passes

Flux core rewards patience more than any other process you will pick up. The welders who get beautiful results with it rarely have the fastest machine; they are the ones who run a coupon and read it before a long production run.

Disclosure: weldgallery.com may earn a commission from some vendor and supply links referenced here, at no additional cost to you.

Frequently Asked Questions

What polarity should I use for flux core welding?

Self-shielded flux core wires such as AWS E71T-11 and E71T-8 run DCEN, also called straight polarity — the electrode lead goes to the negative terminal. That is the opposite of most solid MIG wire, which usually runs DCEP. Running the wrong polarity produces poor arc performance and noticeably more spatter, so check the wire spool and your machine’s polarity connections before striking an arc.

Do I need shielding gas for flux core wire?

Not for self-shielded flux core. The flux inside the wire burns to form its own protective gas, which is exactly why self-shielded FCAW is the go-to for outdoor, windy and dirty-metal work. Gas-shielded flux core (FCAW-G) is different: it needs an external shielding gas, either 100 percent CO2 or a 75-85 percent argon/CO2 blend, and it is normally used for heavy industrial fabrication rather than hobby or field work.

Why does my flux core wire burn back into the contact tip?

Burnback happens when the wire feed speed is too slow for the voltage or the gun is held too close to the workpiece. Increase the wire feed speed, hold the contact tip no further than about 1-1/4 inches from the metal, and replace the contact tip if a weld has already formed inside it. Also confirm you are running a constant voltage power source rather than constant current.

How do I adjust a flux core settings chart for vertical-up welds?

Reduce both voltage and amperage by roughly 10 to 15 percent from the flat-position values because you are fighting gravity, and lower the drag angle to 5 to 15 degrees for vertical up. Vertical up also gives better penetration on thicker material, typically 1/4 inch or more, so it is often the better choice than vertical down on heavy plate.

Can I use my MIG settings chart for flux core wire?

No. Solid wire usually runs DCEP with a much shorter stickout, no slag, and different wire feed speeds for the same amperage. A MIG chart applied to flux core will usually give you a cold, narrow, poorly penetrated bead and heavy spatter. Use the manufacturer data sheet for the exact flux core classification, or a chart explicitly labeled for that wire.

What stickout should I use with flux core wire?

Miller recommends roughly 3/4 inch, about twice the MIG recommendation. Hobart Brothers specifies 1/2 to 3/4 inch for E71T-11 and 1 to 1-1/4 inches for E71T-8 depending on wire diameter, since larger diameter wire generally needs a longer stickout. Keep the wire extending no more than about 1-1/4 inches beyond the contact tip.

Why does my flux core bead have worm holes or worm tracking on the surface?

Worm tracking is created by the gas from the wire’s flux core when the voltage is too high for the given wire feed speed and amperage. Reduce voltage in half-volt increments until the marks disappear. Moisture-contaminated wire can also contribute, so store the wire in its original packaging in a dry area between 40 and 120 degrees F with humidity below 80 percent.

Is E71T-11 wire strong enough for structural work?

It depends on the thickness and the code. E71T-11 wires carry no toughness requirement in their AWS classification, so AWS D1.1 permits them for material less than 1/2 inch thick, and they are most often used for stitch welds and tacks. For anything critical, E71T-8 requires 20 ft-lbs at -20 degrees F, has no thickness restriction, and is approved for demand-critical seismic welds under AWS D1.8/D1.8M.

What is the difference between E71T-11 and E71T-8 flux core wire?

E71T-11 is the easier wire: a wide parameter window, forgiving of technique errors, no toughness requirement and less crack resistance. E71T-8 is the tougher, more demanding wire: 20 ft-lbs at -20 degrees F minimum (or -40 degrees F with the J designator), heavy slag that can interfere with the arc, and a longer recommended stickout of 1 to 1-1/4 inches.

How much wire feed speed do I need per amp on flux core?

There is no single conversion table, but shops commonly use a field rule of thumb of roughly 3 inches per minute of wire feed per amp on .030 wire, trending down toward 1.5 to 2 IPM per amp as diameter increases to .045. Treat that as a sanity check, not a standard, and always start from the wire manufacturer’s data sheet for the specific classification and diameter.