Harbor Freight Welding Chart: How to Read and Use It

Saturday morning, garage door up, a new Harbor Freight inverter on the bench and a 1/8-inch steel bracket waiting to be welded. The little chart taped inside the box lid said 90 amps for 3/32-inch rod, so that is what he set — and got a shower of orange spatter and an undercut bead. Twenty minutes later, with the same chart, the same rod and one small change, the bead came out clean. The chart was not the problem; nobody had explained how to read it. That is the gap this guide closes.

Why Everyone Searches for the Harbor Freight Welding Chart

If you have just opened the box on a Harbor Freight multi-process inverter and spread out the paper chart that came with it, you asked the only question that matters: what settings do I use for this material and this thickness? Here is the straight answer. The Harbor Freight welding chart is a starting-point settings reference, nothing more. It is not gospel and it is not the authority. The authoritative numbers live in three places: the owner’s manual, the output curve on the machine’s nameplate or data plate, and the packaging that came with your electrode, wire, or consumables. The chart in the box summarizes all three, and sometimes it is out of step with one of them. Everything that follows builds on that distinction.

Three different documents share the name “welding chart”

A search for “welding chart” returns three genuinely different things, and mixing them up is a common source of confusion.

• Settings or amperage chart. The most common search, and the one tied to Harbor Freight. It maps material and thickness to machine settings: process, amperage, voltage, wire feed speed, shielding gas and flow rate, and polarity. It is a table of starting points, and it is the focus of this article.
• Electrode or AWS classification chart. These decode the numbers stamped on the end of a stick electrode, such as E6010, E6011, and E7018. The digits tell you the electrode’s strength, operating position, and coating type. If you have ever squinted at “E7018” and wondered what the 7 and the 1 mean, this is the chart you want. The all-position welding rod guide covers the classifications in more detail.
• Welding symbol chart. The graphic language used on engineering drawings: arrow, flag, reference line, and the symbols that specify the weld required. Read a shipyard or structural drawing and this is the chart in the corner of the print. It is a completely different skill from setting amperage, and we return to it in marine and harbor structural work later in this guide.

Who is searching, and what they really want

The audience is specific. These are home-shop and garage welders who bought a budget Harbor Freight multi-process inverter, a flux-core machine, or a plasma cutter and want it working this weekend. They are not fabricating pressure vessels or chasing AWS certification. They have a piece of 14-gauge steel, a length of 3/32-inch rod, a bottle of 75/25 mix, and a torch that has never been fired. They want a fast, plain answer to the settings question before the sun goes down.

Plenty of them already have a good answer and simply do not know it. The manufacturer’s website for the machine, including the manual and specification tabs, is linked from the product listing at harborfreight.com. That is where the real numbers live; the chart in the box is a summary card of a much longer document.

For perspective, AWS maintains more than 350 welding standards through its Codes and Standards program, covering everything from structural steel to underwater welding to the qualification of brazers. A postcard in a cardboard box is not competing with that body of work, and knowing the gap between the two is the first step toward welds that hold.

What this guide will do for you

Three promises, in order. You will learn to read the chart in front of you column by column and understand what each number actually controls. You will learn to verify it against better sources, including the nameplate output curve that tells you what your machine can really deliver on a 110-volt circuit versus a 220-volt one. And you will build your own master chart, based on coupon welds you have actually run, that matches your machine, your materials, and your skill level.

One last clarification on the keyword. Plenty of people searching “harbor freight welding chart” want something else entirely: charts and reference documents used for harbor, port, and marine structural fabrication. Those are not wall posters. They are controlled documents tied to a Welding Procedure Specification, a qualified welder, inspection, and traceability. We cover that world, and the limits of consumer equipment in it, in Section 8.

What the Chart in the Harbor Freight Box Actually Shows You

Most budget welders ship with a single printed card or quick-start insert. It is useful, and it is also the most oversimplified document in the package. Here is what is actually on it, where to find better versions of the same information, and the two variables that quietly make it wrong for a lot of people.

Where to Find the Chart

Start in the box. The card is usually taped inside the lid, folded into the manual, or stuck to the side of the machine. Sometimes it is a thin laminated strip with a handful of settings, sometimes a full instruction sheet with a table on the back.

Then check the product page at Harbor Freight. Manuals and specification sheets live on the product pages themselves, usually under the manual or specifications links on the listing. That document is almost always richer than the card in the box, with full process sections, an output table and, on some models, a proper settings chart. The specifications tab matters just as much, because maximum output, input voltage and duty cycle are listed there.

Keep the paper. A printed chart taped to the wall next to the machine beats scrolling a phone every time you start a job.

What Each Column Actually Means

Charts vary in layout, but the columns are the same ideas wearing different names:

• Process: MIG (GMAW), stick (SMAW), flux core (FCAW), TIG (GTAW), and on plasma cutters, air plasma or oxy-fuel.
• Material: usually mild steel, sometimes stainless steel, aluminium or cast iron as extra rows.
• Thickness: the plate or pipe gauge you are working on. This column determines everything else.
• Consumable diameter: electrode diameter for stick, wire diameter for MIG and flux core. This one gets misread constantly, because people scan down to the amperage column without noticing the row is for 3/32-inch rod.
• Amperage: the machine setting, in amps.
• Voltage: relevant on MIG, flux core, TIG and plasma, where the machine sets arc length for you.
• Wire feed speed: inches per minute on MIG and flux core, and the setting that actually controls how much metal you deposit.
• Gas and flow: shielding gas, mix ratio and flow rate in cubic feet per minute. On self-shielded flux core this row simply says none.
• Polarity: DCEP or DCEN, which matters enormously on stick and gas-shielded flux core.
• Position: flat, horizontal, vertical, overhead. Charts that ignore position assume flat and horizontal work only.

The Hidden Variable: Which Plug Are You On?

Here is the thing nobody explains on the card. Entry-level multi-process welders are almost always sold as dual-voltage, meaning 110V and 220V. The headline amperage in the product listing is normally the 220V figure. Plug that machine into a 110V household circuit and it may deliver a fraction of that output.

A chart printed for 220V operation is simply invalid on 110V. Set 130 amps on a 110V machine that can only make 90 and you get a cold, poorly fused bead with no penetration. The machine cannot deliver what the chart asks for.

The fix is simple and non-negotiable: read the nameplate and the output curve in the manual. Look for output amperage at 110V and at 220V, then note the duty cycle, which tells you how long the machine can hold that output before it overheats and thermally throttles down. Budget inverters often manage a duty cycle around 40 percent at their full rating, and considerably better at lower amperages.

Do not guess. The nameplate is the only reliable source, and it is a free answer taped to the machine you already own.

The Two-in-One Reality

Most budget multi-process machines that offer MIG and flux core share a single gun and a single wire feeder. The mode switch changes polarity and how the machine behaves, but the hardware is the same. That creates a trap: a chart listing solid-wire MIG settings only will mislead you the moment you switch to flux core.

Gas-shielded flux core needs DCEN, a lower voltage range and a different wire feed speed for the same amperage. Self-shielded flux core needs no gas cylinder at all, which is a genuine convenience, but it changes the setup and the fume profile entirely. With no shielding gas the arc is unprotected, the fume plume is heavier and more visible, and extraction matters more, not less.

If you plan to run flux core regularly, treat that section of the manual as a separate document and build your own row set for it. Working with aluminium on the same machine? Our guides on aluminum flux core welding and aluminum MIG welding cover the setup differences the box chart leaves out entirely.

Reading the Card Critically

Before you take a single number off that card, check three things. Which voltage was it printed for? Which process mode does each row describe? And which column are you actually reading, the one for your rod or wire diameter?

A cardboard chart is a starting point. The manual, the nameplate and the consumable packaging are the sources you verify it against, and we will walk through exactly how to do that next.

Reading the Numbers: Amperage, Voltage, Thickness and Wire Feed

The chart taped inside the Harbor Freight box lid is not a mystery document. It is a set of starting points, and once you know what each column means, the numbers turn into ordinary shop math. Amperage, voltage, thickness, wire feed speed, gas and polarity each describe one variable. Here is how to read them.

Stick (SMAW): amperage follows thickness

Start with the simplest rule in welding: about 1 amp of current per .001 inch of material thickness. For mild steel that lands at roughly 125 amps for 1/8-inch plate and about 250 amps for 1/4-inch plate. Divide the thickness in thousandths and you have your starting amperage. If the chart says 110 amps for 1/8-inch steel and the rule says 125, trust the rule until the chart explains itself.

Electrode choice changes the behaviour, not the arithmetic. E6011 is the fast-fill rod: easy to strike, forgiving of scuffed steel, comfortable in most positions. E6010 gives deeper penetration from a slower, more deliberate arc and is the classic root-pass and pipe rod. E7018 is the low-hydrogen workhorse that structural jobs run on, because its coating keeps moisture out of the deposit. All three run DCEN on a budget stick machine: electrode in the holder positive, work negative. The wider differences between the three are covered in the all-position welding rod guide.

Electrode diameter has to match the plate. 3/32-inch rod suits 1/8-inch steel, 1/16-inch rod suits 1/4-inch steel. Running 1/16-inch rod at 250 amps on 1/8-inch plate is a good way to undercut the metal in a single pass. The case for stick welding is worth a read if you are deciding whether to lean on this process.

MIG (GMAW): wire diameter sets the voltage

On MIG the arc voltage follows the wire diameter: roughly 1 volt per .001 inch of wire. So 0.035-inch solid wire typically runs at 17–18 volts, and 0.030-inch wire runs about 16 volts.

Voltage is not a heat control you set freely. It is what the arc settles at once the wire feed speed changes. Feed the wire faster and the arc needs more voltage to stay stable; feed it slower and the voltage drops. That makes wire feed speed the real heat knob on a MIG machine, and it makes the “ipm” column the most useful column on the chart. Every wire spool ships with its own matching chart of feed speed, voltage and amperage, so the spool label is a better reference than any generic poster.

For steel the gas is 75% argon and 25% carbon dioxide, usually printed as 75/25 or C25. That blend gives good penetration with a stable arc and manageable spatter. The same blend works for gas-shielded flux core (E71T-1), while self-shielded flux core runs with no gas at all, which is exactly why a chart listing only solid-wire settings will not get you close in flux-core mode. The Air Gas welding guide explains how shielding gases behave and why the mix matters.

Material	Thickness	Process	Consumable	Amps	Volts	Gas
Mild steel	1/8 in	Stick (SMAW)	E6011, 3/32 in	60–95	20–22	None
Mild steel	1/8 in	Stick (SMAW)	E7018, 3/32 in	70–95	20–22	None
Mild steel	1/4 in	Stick (SMAW)	E7018, 1/16 in	140–230	22–24	None
Mild steel	3/16 in	MIG (GMAW)	ER70S-6, 0.035 in	130–150	17–18	75/25 Ar-CO2
Mild steel	1/4 in	MIG (GMAW)	ER70S-6, 0.035 in	200–230	18–19	75/25 Ar-CO2
Mild steel	1/4 in	Flux core (FCAW)	E71T-1, 0.045 in	180–250	22–26	75/25 (gas-shielded)
Stainless 304L	1/16 in	TIG (GTAW)	ER308L, 3/32 in	90–110	10–13	100% argon
Aluminium 5052	1/8 in	MIG (GMAW)	ER4043, 0.035 in	200–250	22–24	100% argon

MIG wire diameter and starting feed speed

Wire diameter	Typical arc voltage (steel)	Starting wire feed speed	Approx. amperage
0.023 in (0.6 mm)	13–15 V	200–300 ipm	45–70 A
0.030 in (0.8 mm)	15–16 V	250–350 ipm	90–130 A
0.035 in (0.9 mm)	17–18 V	250–400 ipm	120–180 A
0.045 in (1.2 mm)	19–22 V	250–350 ipm	180–250 A

TIG (GTAW): DCEN and the tungsten match

TIG on steel and stainless runs DCEN with roughly 1 amp per .001 inch of thickness and 100% argon shielding. Tungsten choice follows amperage: 2% lanthanated or ceriated tungsten handles most hobby work up to about 150 amps, while finer 1/16-inch tungsten takes higher amperage. A blunt or contaminated tungsten is the number one cause of a wandering arc, so sharpening and cleaning matter as much as the amperage setting. More on tungsten prep and DCEN technique in the aerospace TIG welding guide.

Aluminium: the 2% rule

Aluminium needs about 2 amps per .001 inch of thickness, roughly double the steel rule, and it needs AC current with around 2% balance so the arc scrubs the oxide layer away. Many budget multi-process machines are DC only, which is why the aluminium story usually arrives bundled with a separate spool gun and torch. The aluminum MIG welding guide walks through the process, and getting the metal clean first with a dedicated aluminium cleaner and prep routine matters just as much as the amperage.

Plasma Cutting Charts: Where Harbor Freight Cutters and Their Consumables Fit

Many people search for a Harbor Freight welding chart and end up with a welder. Others bought the plasma cutter instead, and that is where they get stuck: the cutter shipped with consumables and no guide to how they fit together, so the first cut never starts or leaves a thumb-thick bead of dross.

The mental model is simple. Air plasma is the fast, cheap option: a compressed-air arc melts carbon steel and other conductive non-ferrous metals, and on a budget machine from Harbor Freight it slices plate an oxy-fuel torch would take far too long to get through. What air plasma cannot do is cut aluminium or stainless. Those metals carry an insulating oxide layer the air arc cannot punch through, and no amount of amperage fixes it. Oxy-fuel is slower and hotter, but the oxygen jet burns through those oxides, making it the realistic option for aluminium and stainless in most garages.

How to Verify the Chart (and Correct It When Your Machine Disagrees)

The chart in the box is a factory starting guess written for a range of machines, not numbers proven on your unit, in your shop, at your altitude, with your power supply. Treating it as gospel is the single biggest reason a budget inverter produces disappointing welds. Treating it as a hypothesis you can test is the fix. When two sources disagree, work down this list, because each step down is less specific to your situation.

The Source Hierarchy: Which Number Wins

1. Your machine’s manual and nameplate output curve. This is the authority on what your unit can physically do. The output curve shows available amperage at your input voltage, and the nameplate states duty cycle, typically rated at 40 percent on a 10-minute cycle. Our duty cycle guide covers what that rating means when the machine trips on thermal protection mid-bead.
2. The electrode packaging chart. Every can of rods carries a recommended amperage range per diameter. A 3/32-inch E7018 is typically rated around 90 to 130 amps. That number comes from the company that actually made the rod, so it outranks any poster.
3. The wire spool label. For MIG and flux core, the spool lists voltage, wire feed speed range, shielding gas and flow rate for each diameter. ER70S-6 at 0.035 inch usually calls for roughly 17 to 18 volts and a 75/25 argon-CO2 mix at around 25 to 30 cfh on steel.
4. The generic chart. Only now does the Harbor Freight insert, or any wall poster, get a vote. A prompt for what to try first, nothing more.

The Mismatches That Ruin Welds

Most bad welds on budget inverters come down to six specific disagreements between the chart and reality.

1. A 220V Chart Value on a 110V Supply

The most common cause of a cold, poorly fused bead on an entry-level machine. A dual-voltage inverter sold at Harbor Freight may list 130 amps of output on 220V but far less on 110V. Set 130 amps from the chart while plugged into a household circuit and the machine physically cannot deliver it. What you get is a soft, wandering arc that looks like a settings problem but is really a power problem. Check the output curve for your input voltage before blaming anything else, then step down to the highest value you can actually reach and re-test.

2. Material Thickness Confused with Electrode Diameter

These are not the same number, and swapping them is easy. 1/8-inch steel generally wants 3/32-inch rod at roughly 90 to 125 amps, while 1/4-inch steel wants 1/8-inch rod and considerably more current. Using 1/8-inch rod on 1/8-inch plate overloads the amperage, the rod melts faster than you can move it, and the result is stubbing and a wandering arc.

3. Position Ignored

Vertical-up welding generally needs about 10 percent less amperage than flat position, plus stringer beads rather than wide weave, because the pool runs downhill and a hot, wide pool will sag or undercut. If your chart has one row per thickness and no position column, you are reading a flat-position number into a vertical weld.

4. Dirty or Mill-Scale Steel

A chart assumes clean metal. Mill scale is oxide. Rust is oxide. Welding through either traps gas and prevents fusion, and no amperage setting fixes a contaminated joint. Grind or at least wire-wheel the surface before welding, especially for anything load-bearing.

5. Stainless or Aluminium Welded with the Carbon-Steel Row

Stainless and aluminium need different consumables, different cleanliness standards and often a different process entirely. Carbon steel wire on stainless risks contamination and rusting of the weld. Aluminium needs its own dedicated program and prep, and our aluminum cleaner guide covers the surface prep step that matters most before arc strikes. Running an aluminum job off the carbon-steel row of a chart is a good way to waste a spool.

6. Outdoor Wind Killing Gas-Shielded Wire

Gas-shielded processes fail outdoors in wind, and even a light breeze disrupts the shielding and causes porosity. There is no chart value that fixes this. You need a windshield, a garage door up only if there is no cross draft, or you move to a flux-core process that does not depend on shielding gas.

Build Your Own Numbers: The Scrap Coupon Method

Charts get corrected by writing on them. Take offcuts of the same material and thickness you actually work with, and run single-pass fillet beads on them.

1. Start at the middle of the range from the packaging, not the top of the chart.
2. Weld a single-pass fillet, roughly an inch long, on scrap of the correct thickness.
3. Change one variable at a time in small steps, typically two amps or one volt, and write down what each change did.
4. Judge the bead on three things: penetration into the base metal, bead shape, and spatter level.
5. Photograph the bead with your phone and note the settings beside it.
6. Rewrite the chart row with your verified numbers once the bead looks right.

Ten minutes of coupon testing will teach you more than a poster chart ever will, because the numbers now belong to your machine, your power and your hands.

Once the chart matches your machine, your power and your materials, it stops being a poster and starts being a tool. That is the whole point.

Safety: What the Chart Can Never Tell You

A settings chart answers one narrow question: how hot should the arc be? It tells you nothing about the plume of metal vapour rising off your head, the sparks landing on your neighbour’s plywood, or the arc light frying your retina at 20 amps. Those are the parts of welding that can send you to an emergency room, and they live entirely outside the little laminated card taped inside the box lid.

Most home-shop injuries are not dramatic. They are cumulative: fume fever on a Friday afternoon, a burn from a spatter droplet that rolled inside your glove, a flash burn from an arc you started without raising the hood. So treat this section as the part of welding you learn before you learn anything else.

Fume Control and Ventilation

Under OSHA’s welding standard, 29 CFR 1910.252, mechanical ventilation is required at a minimum of 2,000 cubic feet per minute per welder in spaces that are under 10,000 cubic feet per welder, where ceilings are under 16 feet, or where partitions obstruct cross-ventilation. In a one-car garage with a bead-blasting cabinet and a fridge in the corner, that condition is met almost every time you weld.

Local exhaust is the better answer, and OSHA publishes the airflow numbers that make it simple. A movable hood should hold a control velocity of 100 linear feet per minute at the arc. The hood airflow table shows what that requires in practice:

Distance from arc to hood inlet	Minimum airflow	Minimum duct diameter
4 to 6 inches	150 cfm	3 inches
6 to 8 inches	275 cfm	4 inches
8 to 10 inches	425 cfm	5 inches
10 to 12 inches	600 cfm	6 inches

Translate that into shopping: a small fume extractor with a 4-inch flexible arm, rated around 275 to 425 cfm, will handle most bench work if you keep the hood within 8 inches of the arc. A shop vacuum with a welding-rated HEPA filter is a cheaper second option, and a cross-vented garage door open on a mild day beats nothing at all. What does not work is a fan pointed away from the arc, because you have just made the plume mobile rather than removed it.

Fire Prevention

OSHA requires that combustible materials be moved at least 35 feet from the work area, and that the 35-foot radius be swept for combustibles before work starts. If combustibles remain within 35 feet, a fire watch with an appropriate extinguisher is required, and that watch must be maintained for at least 30 minutes after welding or cutting finishes. Thirty minutes matters because glowing slag and hidden embers in a 2×4 stud or a pile of rags can smoulder long after the arc goes cold.

For the home shop, the practical version is a metal fire extinguisher (dry chemical or CO2) mounted near the door, a clear path to it, and a rule about not welding over a deck of scrap with rags and packaging foam underneath. A 5-gallon bucket of water for hot-work in a residential garage is cheap insurance that costs almost nothing.

Eye and Face Protection

Filter shade selection is the part of safety people get wrong most often, and OSHA’s guidance is specific. For shielded metal arc welding with electrodes from 1/16 inch to 1/8 inch, the filter shade is 10. For gas-shielded arc welding of ferrous materials, and for SMAW with electrodes from 3/16 inch to 1/4 inch, the shade is 12. For SMAW with electrodes from 5/16 inch to 3/8 inch, the shade is 14. Gas cutting and oxy-fuel cutting sit higher still, with shade 12 for light gas cutting, shade 13 for heavy gas cutting, and shade 14 to 16 for oxy-fuel cutting depending on the work.

The practical buying advice: a shade 12 auto-darkening helmet covers the majority of home-shop work, from thin MIG on sheet metal to 1/8-inch stick. Do not go darker than you need, because an over-dark shade means you are fighting to see the puddle, and a welder who cannot see the weld will fight the settings instead of reading the chart. Side shields, a leather bib and sleeves, and flame-resistant clothing complete the picture. Cotton is a poor choice; synthetics melt, and that is a burn waiting to happen.

What the Fumes Actually Are

The NIOSH Pocket Guide entry for welding fumes lists welding fumes as a potential occupational carcinogen, identifies the lung as a cancer site, and names metal fume fever among the symptoms. Metal fume fever is the flu-like headache, chills and cough you get a few hours after a heavy session on galvanised or stainless steel. It is not the same as the long-term risk, but it is a good indicator that your extraction is not keeping up.

Manganese is the neurotoxin people underrate. NIOSH’s welding fumes and manganese guidance lists a recommended exposure limit of 1 mg/m³ as an 8-hour TWA and 3 mg/m³ as a short-term exposure limit, compared with OSHA’s permissible exposure limit of 5 mg/m³ as a ceiling. The gap matters: the OSHA ceiling permits short bursts far above the level NIOSH considers safe over a full shift. Chronic exposure above 1 mg/m³ is associated with manganism, a Parkinson-like neurological condition, and with neurobehavioral effects such as slowed reaction time and tremor. NIOSH also notes that confined space welding significantly increases exposure, because there is nowhere for the plume to go.

NIOSH’s 2022 welders’ anthrax bulletin adds a different hazard worth knowing: Bacillus cereus spores in the air can survive in a welding helmet’s inner surfaces and cause skin infections. Cleaning the helmet liner routinely is not fussiness.

Special Materials and Special Rules

Some work carries its own requirements, and all of them point the same way: get the fume out of your breathing zone.

• Galvanised (zinc) steel: zinc oxide fume causes metal fume fever within hours. Use local exhaust and, for heavy or prolonged work, respiratory protection.
• Lead and cadmium: both are severe toxic hazards requiring local exhaust and respiratory protection, plus hygiene discipline to keep dust off your clothes and out of the vehicle.
• Beryllium: OSHA treats beryllium as a serious carcinogen requiring controlled exposure and, in many cases, an air-supplied respirator.
• Stainless steel: hexavalent chromium fume is the concern, so a fume extractor matters more here, not less. See our alloy steel welding electrode selection and safety guide for the filler side of the same problem.
• Cleaning solvents: degreasing before welding means a solvent vapour plus an arc. Do not weld over solvent residues; clean first and let the vapours clear.

Heat, Confined Spaces and the Bottom Line

Welding in full PPE is heavy work in a radiant heat environment, and OSHA’s heat guidance applies: water, rest and shade, acclimatisation for new workers, and assessment using the WBGT heat index rather than temperature alone. A welder in flame-resistant clothing, leather gloves, a helmet and a respirator loses a lot of evaporative cooling. Schedule breaks like you would for a summer roof job.

Confined spaces add rules that are not optional. Cylinders and welding machines stay outside the space. An attendant with a preplanned rescue remains outside at all times. Oxygen is never used for ventilation, for any reason, ever. If you cannot meet those conditions, the job does not happen that day.

None of this appears on the chart taped inside the Harbor Freight box, which is precisely why it matters. If you want the fuller picture of fume control, PPE selection and shop setup, our aluminium MIG welding practical guide covers the process-specific safety details, and the guide to prepping aluminium for welding covers the cleaning step that keeps fume and contamination down at the same time.

Common Chart Mistakes and How to Fix the Weld They Cause

Here is the thing about chart mistakes: very few of them are the machine’s fault. A budget multi-process inverter does exactly what it was told. The bead fails because the number printed on the card and the number the joint actually needed were different, and the chart never tells you what to change next. Learn to read the symptom, name the mistake behind it, and you can fix most bad welds without buying a single thing.

These are the nine failure modes you will hit most often, the chart error that usually causes each one, and the correction that works.

Symptom	Chart mistake behind it	Correction
Orange spatter, rough popping bead	Arc voltage too high for the wire diameter, or wire feed speed too low for the amperage	Drop voltage 1 V at a time; raise wire feed speed until amperage matches the chart
Stubbing, wire arcing back into the gun	Wire feed speed too high for the voltage, or voltage too low for the feed speed	Raise voltage 1 V at a time, or slow the wire feed down
Undercut along the toe of the bead	Too much amperage for the position, or travel speed too fast	Drop amperage about 10 percent; use stringer beads vertical-up
Lack of fusion (bead sits on top and melts nothing)	Heat input too low for the thickness, dirty or mill-scale steel, bead off the joint, travel too fast	Grind to bright metal, aim the arc at the joint, slow down, add heat
Porosity, pits and pinholes	Gas flow too low or too high, blocked gas nozzle, drafts, contaminated wire or liner	Set flow to the spool label (about 20 to 25 cfh for MIG steel); check nozzle, hose and liner
Electrode sticks to the work in stick welding	Amperage too high for the rod diameter	Match amperage to the rod: 3/32-inch rod for 1/8-inch steel
Tungsten wanders, arc will not stay put in TIG	Amperage too high for the tungsten diameter, blunt or contaminated tungsten, wrong grind taper	Use the correct tungsten size, re-sharpen it, drop the amperage
Hot cracking in aluminium	Too much heat, oxide left on the joint, wrong filler metal	Lower amperage, use AC with about 2 percent balance, brush the joint clean
Flux core stubbing and wire arcing back	Wire feed speed too high for the voltage, or wrong polarity for self-shielded wire	Slow the feed, raise voltage, and check polarity on the machine chart

Spatter and Stubbing: Getting Voltage and Wire Feed to Agree

These two are mirror images of each other. Spatter means the arc is too long or the wire is moving too slowly for the amperage you set, so droplets form on the tip and spit. Stubbing means the wire is feeding faster than the arc can melt it, so it touches the puddle and arcs back into the gun. The corrective habits are equally opposite: spatter responds to less voltage or more wire feed, stubbing responds to more voltage or less wire feed.

Most budget charts hand you one number for wire feed speed and one for voltage and expect you to trust both. The missing variable is your machine. A110 V inverter rarely duplicates the 220 V settings, so if the chart was written for220 V and you are plugged into a 15 A outlet, you will chase spatter forever. Check the nameplate output curve for the voltage you actually have.

Undercut: The Vertical Problem

Undercut is a groove melted along the toe of the bead where the arc was pointing, and on a chart-driven setup it almost always comes down to too many amperes for the position. Flat and horizontal joints forgive extra heat. Vertical joints do not, because the arc is fighting gravity and the puddle is trying to run. Dropping amperage by roughly 10 percent and switching to stringer beads is the standard correction, and vertical-up rather than vertical-down gives you more time to control the puddle. The all-position rod guide covers which electrodes handle vertical work best.

Porosity: When the Shielding Gas Fails You

Porosity is a shielding problem before it is a settings problem. Gas flow that is too low lets the atmosphere reach the molten pool; flow that is too high can blow the shielding away and drag contamination in. A blocked or damaged gas nozzle does the same thing while looking perfectly fine, and a contaminated liner or dusty wire can put moisture and oil right into the arc. The chart gives you a flow rate, so set it from the spool label and then verify the actual cylinder pressure and regulator at the machine, not just the gauge on the bottle. Drafts do the same damage: work outside with any wind and the gas cover collapses, which is another argument for a process that does not depend on shielding gas when you are out in the yard.

Stick and TIG: Diameter Mismatches

Electrode sticking is an amperage-versus-diameter mismatch. Too much current for a thin rod and the puddle becomes a molten puddle, the tip floods and welds itself to the work. Match the rod to the material thickness and drop the amperage to the middle of the packaging range rather than the top of it.

Tungsten wandering looks like a machine fault and almost never is. It is the amperage exceeding what that tungsten diameter can carry, or a tungsten that has been blunted, contaminated with filler, or ground to the wrong taper. Fix the tungsten, not the machine: grind it on a dedicated wheel, use a taper matched to your process, and keep the amperage inside the tungsten’s rated range. More detail on the setup is in the aluminium MIG guide, which covers clean setups and machine behaviour in depth.

Aluminium: Heat Control and Clean Metal

Hot cracking in aluminium is a heat and cleanliness problem. Too much heat input opens the joint up while the filler is still hot, and any oxide left on the plate melts into the puddle and refuses to fuse. Drop the amperage, keep AC balance near 2 percent for MIG work, brush the joint and filler immediately before welding, and choose the right filler. Getting the joint truly clean takes more than a rag, and the aluminium prep guide covers the chemistry behind it. Aluminium oxide fume is a real respiratory hazard too, which is why fume control belongs in this conversation and not only in a safety manual.

Fix the Hardware Before You Fix the Settings

Before touching a single knob, rule out the hardware. A snag in the gun liner makes the wire feed erratically and looks exactly like a voltage problem. A worn contact tip causes stubbing. A dirty or loose ground clamp starves the arc of current and gives you a bead that fuses halfway. A bent wire straightener feeds the wire off-centre so it wanders. Check the liner, contact tip, ground clamp and straightener, and you will often find the “chart problem” was never a chart problem at all. If you are still stuck after that, the honest question is whether the machine or the technique is the limit, and the gear review and comparison guides on the site are written for exactly that decision.

Where the Chart Falls Short: Code Work, Marine and Harbor Projects

While the majority of people searching for a Harbor Freight welding chart are simply looking for amperage settings for their garage, the word “harbor” does hold a second meaning. In shipyards and ports, a welding chart is not a laminated card taped to a machine lid. These are controlled documents, with every single variable accounted for to ensure the safety of the people that rely on them.

Settings Charts Versus Code Compliance

Any weld that falls under structural, pressure-retaining, or safety-critical work requires a fully traceable process. This starts off with a Welding Procedure Specification (WPS), written specifically against a governing code. From there, welders must be qualified through performance tests to follow that exact procedure. On top of this, code work requires strict inspection and full consumable traceability. A consumer settings chart provides none of these requirements.

These jobs are held to some of the industry’s most strict standards. For structural steel, fabricators must abide by AWS D1.1/D1.1M:2025-AMD1. For aluminum structures, AWS D1.2/D1.2M:2026 is used, whilst bridges fall under AWS D1.5:2025. For stainless applications, AWS D1.6 is referenced, alongside the welding terminology outlined in AWS A3.0M/A3.0:2025. Pressure vessels and boilers take it a step further, utilizing ASME BPVC Section IX for all qualification purposes.

The Language of Welding Drawings

Walking into a shipyard, you’ll quickly find that the most important chart isn’t for amperage at all. It’s the welding symbol chart found on engineering drawings. Governed by AWS symbol standards, these symbols utilize the arrow, reference line, flag, and tail to specify joint type, weld size, length, position, and whether a weld is a field, shop, or all-around weld. This is an entirely separate skill set from dialing in your machine. To obtain these qualifications, AWS certification and education pathways are able to provide credentials such as the Certified Welding Inspector (CWI), Certified Welding Supervisor (CWS), Welder Performance Qualification (WPQ), and Welding Procedure Qualification (WPQ2). None of these can be obtained by reading a box-top settings chart.

Consumer Gear Simply Isn’t Up To The Task

With all of this said, the hardware itself is the largest hurdle. The vast majority of consumer inverters lack consistent arc control, preheat control, and the duty cycle needed for structural, pressure, or marine code work. Most importantly, they cannot produce the documented, repeatable, traceable results that a code inspector would require. With that being said, these machines are still phenomenal for garage and hobby work. For those looking to take on hull repairs themselves, however, projects of this caliber call for a completely different level of preparation, such as the ones covered within our guide for Aluminum Boat Welding: The Complete Guide for Strong Hull Joints.

Harbor-side work comes with its own set of added stressors as well. The combination of salt and moisture will aggressively drive corrosion, making proper filler selection and post-weld cleanup vital to the lifespan of a repair. Coated or galvanized steel also requires drastically different fume controls compared to bare mild steel. These jobs are also legally held to more than just the general welding standard. Shipyard employment falls under OSHA’s maritime standards (29 CFR Part 1915) in addition to 29 CFR 1910 Subpart Q.

Building Your Own Master Welding Chart (The Version You Will Actually Use)

The chart printed inside the box lid was written for an imaginary welder in an imaginary shop with imaginary material. The chart on your wall is different. It is built from your machine, your wire, your gas, your materials and your own hands, and it is the only one that reliably predicts what you will see when the arc strikes.

Building it takes an afternoon to set up and then ten minutes every time you try a new material or thickness. Here is how to do it properly.

Start With the Template

Give yourself one row per material and thickness combination, and these columns across the top:

Material & Thickness	Process	Consumable & Size	Amps	Volts	Wire Feed (ipm)	Gas & Flow	Polarity	Position	Notes
1/8″ mild steel	MIG	ER70S-6 .030″	90	16	250	75/25 @ 20 cfm	DCEP	flat	Bead slightly convex, minimal spatter
1/4″ mild steel	Stick	E7018 3/32″	120	–	–	–	DCEN	flat / horiz.	Short beads, chip slag between passes
1/4″ mild steel	MIG	ER70S-6 .035″	160	18	420	75/25 @ 25 cfm	DCEP	flat	Watch for undercut at high travel speed
16 ga. stainless	TIG	ER308L .035″	70	–	–	100% Ar @ 15 cfm	DCEN	flat	Use 2% thoriated tungsten, tungsten 1/16″

Leave a cell blank rather than guessing at it. A blank tells you honestly that you have not tested that combination yet, and it becomes a to-do item. The notes column matters more than most people expect, because it captures the tiny deviations that made the difference between a sound bead and a slag-crusted one.

Where to Source Baseline Data Responsibly

Work your way down this list, and stop trusting any number that does not come from one of these sources:

• The machine manual and nameplate output curve. Your amperage ceiling at your actual input voltage is the first constraint.
• The electrode can chart and the wire spool label. These are the gold standard for starting points because they match the consumable in your hands.
• Consumable manufacturer technical literature. The data sheets and welding guides from the rod and wire maker cover joint preparation, gas flow, wire feed ranges and often a suggested settings table for common thicknesses.
• AWS free resources. If you want to go past a wall chart, the AWS education and training programmes publish free welding material for welders who want real understanding rather than a lookup.

What you should not do is print off a stranger’s poster from a forum or a social post and weld from it. Those charts were built on someone else’s machine, wire and material. They are useful as a sanity check and dangerous as gospel.

Run Coupon Tests and Log Everything

Grab a piece of scrap in the same thickness as your real work and run single-pass fillet beads. Change one variable at a time. After each bead, record five things: material, thickness, position, the settings you used, and how the bead turned out.

Then take a phone photo of the bead and glue it next to the entry. Within a month you will have a visual reference that tells you more than a column of numbers ever could, because you can finally see what “slightly convex with almost no spatter” actually looks like on your machine.

Keep it simple: a spiral notebook or a phone note, with the chart itself in the same drawer or the same folder. Then tape the finished sheet to the wall next to the machine, where you will actually see it with the safety glasses already on.

Three Ways to Keep It Accessible

1. A laminated paper chart. Cheap, immune to grease and shop dust, and works with gloves on. Lamination takes a few minutes with a self-adhesive pouch.
2. A phone photo of the chart. Faster to update than a reprint, and it lives in your pocket when you are at a job site instead of in the shop.
3. The machine’s own material presets. Convenient, and worth understanding: on multi-process machines these adjust voltage and wire feed speed together as a matched pair. That is a sensible factory compromise, but it is still a generic baseline. Verify each preset against your own coupon results and write your corrections next to it.

Upgrade or Stretch: A Decision Guide

Upgrade	When It Genuinely Pays Off	Stretching the Budget Inverter
220V branch circuit	Biggest single performance change most home shops can make. More output, better heat control, fewer frustrating cold beads.	Verify the machine nameplate amperage and duty cycle at 110V before blaming the welder.
Higher duty cycle machine	You are doing production work, or long structural joints that would trip thermal protection.	Work in short passes and let the machine cool; ventilation is required either way.
Spool gun	The standard route to aluminium in a home shop. The push-pull feeder and liner manage soft, conductive wire that a regular feeder will kink. See our aluminium MIG welding guide.	Clean the liner, use the right contact tip and keep argon dry and flowing.
Pulse MIG	Thin-gauge stainless and aluminium where you need heat control without spatter.	Use smaller wire, lower travel speed and a thinner gas cup.
Fume extractor	Any shop where you weld stainless, galvanised or aluminium regularly, or weld indoors.	Open a garage door, position a fan to pull air away from your face, and wear the right respirator.

On the consumable side, buy reputable ER70S-6 wire and E7018 rods with legible date codes and mill certificates. That documentation is what makes your chart values repeatable months later, when you want to know whether the wire you used today is the same wire you used in March.

And if you are picking rods for vertical and overhead work in the meantime, our all-position rod guide covers the classifications worth keeping on your own chart.

Bottom Line: Use the Chart, Then Trust Your Own Notes

Here is the short version of everything above, in the order that matters when you are standing over a hot metal with a project on the line.

1. The chart in the box is a starting point, not a specification. It was written for a range of machines, inputs and conditions, so treat it as “try this first.” The Harbor Freight documentation and the consumable packaging are what you actually verify against, and the Harbor Freight product pages are where the downloadable manual and specifications live.
2. Your manual, nameplate and consumable packaging outrank any chart. The nameplate output curve tells you what your machine can really deliver at 110V versus 220V, the manual gives the duty cycle, and the rod box or wire spool label gives the amperage range, voltage and gas mix for the consumable in your hand.
3. Match the chart to your power source and your process mode. A solid-wire row from the chart does not apply when you are in flux-core mode, and a 220V number on a 110V circuit is a number your machine cannot reach. Read the label on the panel, not the sticker on the lid.
4. Correct for position, material and environment. Vertical-up usually wants about ten percent less amperage than flat work, stainless and aluminium have their own rows that are not interchangeable with carbon steel, and any breeze will spoil a gas-shielded bead.
5. Safety sits in front of the chart, every single time. Fume control, fire watch, eye protection and heat management are governed by OSHA’s welding standard, and no settings chart covers any of it. A clean bead is worthless in a space you should not have welded in.
6. Write down your own verified numbers. Run coupons on the same thickness and material you actually use, record what worked, and keep your own chart in the same place as the machine. In a year it will be worth more than anything printed on a poster.
7. Know what your machine is for. Garage and hobby fabrication is exactly what consumer inverters are built for. Code, structural, marine and pressure work needs a qualified procedure and a qualified welder, becauseAWS codes require documentation, not a good guess.

Want to keep going? Our welding guides library covers the rest of the ground, and a few pieces pair up naturally with this one. Read the duty cycle guide if you want to understand exactly how hard you can push your machine and why the 40 percent rating is the number that limits your cut sizes. If you are still choosing a process rather than mastering one, the MIG versus TIG comparison walks through heat input, control, filler options and where each process earns its keep. For fumes, PPE and shop practice, the welding safety and tips section is the reference to keep open on the bench, and if you have ever wondered how a diver welds a pipeline in the dark, the underwater welding explainer is a good look at welding in the most demanding environment there is. It makes the case for chart discipline and safety discipline in one breath, because underwater, a wrong amperage and a missing hood are the same kind of problem.

And if you are working with aluminium, the practical guides on aluminium MIG welding and aluminium flux core welding cover the cleaning and polarity details that carbon steel charts never mention.

Start with the chart. Cross-check it. Then write your own version and believe that one, because it came out of your machine, your material and your hands. There is no substitute for a bead you pulled apart to see what was really happening.

Below that, the FAQ block answers the eight questions that come up most often in shop conversations and in the comments: what amperage for 1/8-inch steel, stick versus MIG, flux core with or without gas, what to do about spatter, can a Harbor Freight welder handle stainless or aluminium, what polarity for 6011 and 7018, and why your beads keep undercutting. If your question is not in there, the answer is probably in your coupon notes.

More from Weld Gallery: browse our gear reviews and comparisons when the problem is the machine rather than the technique.

Frequently Asked Questions

Where do I find the welding chart for my Harbor Freight welder?

Look for a printed quick-start card or instruction insert in the box, then check the product page on harborfreight.com for the downloadable manual under the manual/specifications links. Because Harbor Freight sells several generations of multi-process machines, always match the chart to the exact model number on the nameplate. If the manual is missing, contact Harbor Freight customer service for the current version.

What amperage should I use for 1/8-inch steel with a 3/32-inch 7018 rod?

Start around 90 to 110 amps on DCEN, which matches the common rule of about 1 amp per .001 inch of material thickness. Fine-tune by watching bead shape: a flat, slightly rippled bead means add a few amps, while a rounded, blobby bead with undercut means back off. Always check the amperage range printed on the electrode can for the specific rod.

Why can my welder not reach the amperage on the chart when I plug it into 110V?

Most entry-level inverters output far fewer amps on 110V than on 220V, and the nameplate output curve will show both figures. The chart assumes the machine is running at its rated input. Run a 220V circuit with proper breaker size and wire gauge, and treat any chart value your machine cannot physically reach as unattainable rather than as a fault.

Is the chart on the box accurate for stainless steel or aluminium?

Usually not — most printed charts cover carbon steel with the common processes only. Stainless needs lower heat, matching filler such as ER308L and different amperage expectations, while aluminium needs AC with roughly 2% balance, a spool gun and the 2% amperage rule. Build separate rows for those materials from your own coupon tests.

Can I use a Harbor Freight welder for structural, marine or harbor work?

For code-governed, structural, pressure-retaining or marine work, no — those jobs need a written Welding Procedure Specification, qualified welders, inspection and consumable traceability under AWS D1.1, AWS D1.6 or ASME BPVC Section IX. Consumer inverters are excellent for garage, hobby and farm-shop fabrication where no code applies.

How do I read the voltage column on a MIG welding chart?

Arc voltage in MIG is set mainly by wire diameter: roughly 1 volt per .001 inch of wire diameter, so 0.035-inch wire usually runs 17–18 volts and 0.030-inch about 16 volts. Higher voltage widens the arc and flattens the bead, lower voltage narrows it and raises spatter. Adjust in one-volt steps while holding wire feed speed steady.

Why does my flux-core wire keep stubbing and arcing back?

Stubbing usually means the wire feed speed is too high for the voltage, or the gun is running in the wrong mode. Check that the machine is set to flux core rather than solid wire, confirm the polarity matches the flux core chart, and slow the wire feed speed down until the arc stabilises before adjusting voltage.

Is there a free Harbor Freight welding chart PDF I can download?

The manuals on the Harbor Freight product pages are the official free documents and usually include a settings chart for the machine. Beyond that, the best chart is the one you build yourself from the manual, the electrode can chart, the wire spool label and your own coupon tests — that is the version that matches your machine, your materials and your skill level.

How do I set the machine for vertical-up stick welding?

Drop the flat-position amperage by roughly 10 percent and use short stringer beads instead of weaving, so the puddle stays small. If you see undercut along the toes of the bead, you are still too hot for the position — reduce amps again in 5 to 10 amp steps before touching anything else.