Welding for beginners: 7 tips for your first good welds

Almost everyone's first welds look the same: spatter, a rod stuck to the plate, slag trapped in the bead and a hole burned through the sheet. The good news is that most beginner mistakes have simple causes, fixed through settings, preparation and hand position. Below are 7 tips for stick welding (MMA/SMAW) with concrete numbers: which amperage to pick, how many rods to buy and how long the machine can run before it stops.

In short

To start: a 160–200 A MMA inverter and rutile rods of 2.5 and 3.2 mm.
Quick amperage rule: about 35–40 A per millimetre of rod diameter, then adjust by how the puddle flows.
Grind the metal bright for 20–25 mm on each side of the joint. Rust and paint cause porosity.
Arc length ≈ rod diameter. A long arc means spatter and porosity.
A 4 mm fillet weld over 10 m uses about 2.3 kg of rutile rods.

1. Pick a forgiving machine

For a workshop or home use, a 230 V MMA inverter is the simplest choice. Look for three features that help a lot at the start:

Hot start: briefly boosts the current at striking so the arc starts easily.
Arc force: pushes current up when the arc gets short so the rod does not go out.
Anti-stick: cuts the current when the rod sticks so you can free it before it glows red.

Then check the duty cycle. "160 A at 60%" means that in a 10-minute cycle the machine can hold the arc for 6 minutes at 160 A, then needs to cool. The current it can run continuously (100%) is estimated with I₁₀₀ = I₆₀ × √0.6:

Machine	Current at rated duty	Calculation	Current at 100% (approx.)
160 A inverter	160 A at 60%	160 × √0.6	124 A
200 A inverter	200 A at 35%	200 × √0.35	118 A

The takeaway: a 200 A machine with a low duty cycle is not necessarily "stronger" in continuous work than a 160 A machine with a high one. For a 3.2 mm rod at 100–120 A, either is enough. Also check your breaker: a 160–200 A inverter usually draws 16 A or more from the socket at full output.

2. Start with rutile rods and the right amperage

Rutile rods (on the box: E 42 0 RR 12 or AWS E6013) strike easily, have a calm arc and slag that peels off well. They are a good choice for gates, fences, shelving and repairs. Basic rods (E 42 4 B 42 H5 or E7018) give tougher welds for loaded structures, but must be oven-dried before use and need more skill. If you are not sure what a box label means, the consumable decoder explains every field.

Rod diameter	Material thickness (guide)	Rutile current (guide)
2.0 mm	1.5–3 mm	50–70 A
2.5 mm	2–5 mm	60–95 A
3.2 mm	4–8 mm	90–130 A
4.0 mm	6–12 mm	130–180 A

Values vary between manufacturers. Start in the middle of the range printed on the box and adjust.

How to read the setting from the result: if the rod sticks and the bead sits tall on top, the current is too low. If it spatters a lot, the rod glows red halfway or the edges are undercut, the current is too high. Keep rods dry: rods that have picked up moisture cause porosity even with the right setting.

3. Prepare the metal before you strike

Half of a good weld is done with the grinder. Remove rust, paint, oil and mill scale down to bright metal for 20–25 mm on each side of the joint. Dirty metal gives porosity and slag inclusions however steady your hand is.

Butt joints up to 3–4 mm: square edges with a 1.5–2 mm gap so the weld penetrates.
Above 5–6 mm: bevel the edges into a V (about 60° included) and leave a 1–2 mm root face.
Ground clamp: on clean metal, as close to the weld as possible. A poor ground makes the arc unstable.
Tack welds: short tacks at the ends and every 10–15 cm so the parts do not move as they heat up.

How accurately the parts are cut matters too. A gap that varies from 0 to 4 mm along the joint is very hard to weld evenly, even for an experienced welder. When parts arrive cut to the right length and angle, for example from a plan made in Steel Cut Pro, fitting and welding go much faster.

Do not weld galvanised or painted steel without removing the coating from the weld area and without good ventilation. Zinc fumes cause metal fume fever.

4. Strike the arc without sticking the rod

There are two methods. Scratching is like striking a match: drag the rod tip briefly across the work and lift it straight away to 2–3 mm. It is the easiest to learn. Tapping means touching the work briefly with the tip and lifting at once. It is more precise and useful in tight corners.

Once the arc is lit, keep the arc length about equal to the rod diameter: 2.5 mm for a 2.5 rod, 3 mm for a 3.2 rod. Too long an arc crackles, spatters and leaves porosity. Too short and the rod sticks. As the rod burns down, your hand has to move steadily closer, and that only comes with practice.

Practise on offcuts, not on the finished part. A 40×40×4 angle works well: thick enough not to burn through, and you can practise both fillet and butt welds on it.

5. Watch the puddle, not the arc

Through the mask, look at the molten puddle behind the arc, not at the arc light. It tells you everything:

Travel angle: tilt the rod 10–20° back towards where you came from (drag the bead). On a fillet weld hold it at about 45° between the two parts.
Speed: a good bead is 2–3 times as wide as the rod diameter. Narrow and tall means you are going too fast. Wide, with the puddle running ahead of the arc, means too slow.
Sound: a steady sizzle, like bacon in a pan, means a stable arc. Popping and interruptions mean the arc is too long.

On thin tube, for example 30×30×2, drop to a 2.0–2.5 mm rod at 55–75 A and weld in linked stitches if you keep burning through. Fence and gate tube is where beginners burn holes most often.

6. Work out the rods, then inspect every bead

Before buying, you can estimate consumption. Example: a fillet weld with throat a = 4 mm and a total length of 10 m:

Step	Calculation	Result
Cross-section (equal fillet)	a² = 4 × 4	16 mm²
With reinforcement (+10%)	16 × 1.10	17.6 mm²
Deposited metal per metre	17.6 cm³ × 7.85 g/cm³	138 g/m
Deposited metal over 10 m	138 × 10	1.38 kg
Rutile rods (~60% efficiency)	1.38 ÷ 0.60	≈ 2.3 kg

The 60% efficiency covers stub ends, spatter and the coating that turns into slag. With 3.2 × 350 mm rods that is about 65 rods. The consumables calculator does the same calculation for V, X, U and fillet joints, including arc time and cost.

After each bead, knock off the slag with a chipping hammer and wire brush and look closely at the weld:

Defect	What it looks like	Likely cause	What to change
Porosity	small holes on the surface	dirty metal, damp rods, long arc	clean, dry the rods, shorten the arc
Undercut	a groove along the bead edge	current too high, wrong angle	drop 10 A, point the rod at the affected wall
Lack of fusion	bead sitting on top, cold edges	low current, high speed	raise the current, slow down
Slag inclusion	black spots in the bead	slag from the previous pass not removed	clean well between passes
Heavy spatter	droplets stuck to the part	high current, long arc	lower the current, bring the rod closer

7. Protect yourself like a pro from day one

The welding arc emits ultraviolet radiation that burns eyes and skin within seconds. An auto-darkening helmet is the best first investment: you see the part through the lens before striking and keep both hands free. For MMA between 40 and 150 A a filter shade of DIN 10–11 is usually used, and DIN 11–12 above 150 A.

Dry leather gloves and cotton or flame-resistant clothing. Synthetic fabrics melt onto the skin.
Safety glasses under the helmet, for grinding and chipping slag.
Ventilation: keep clean air at your face, not your head in the fumes.
Fire: clear flammables within a few metres and check the area for at least 30 minutes after you finish.
Electrical: do not touch the rod and the work with wet hands and never weld standing in water.

Frequently asked questions

What amperage for a 2.5 mm rod?

Between 60 and 95 A, depending on the manufacturer and the thickness of the part. On 3 mm plate start at about 75 A.

Can I learn to weld on my own?

You can learn basic welding for repairs and your own projects by practising on offcuts. Structures that carry loads or people (stairs, railings, halls) must be welded or checked by a qualified welder.

Why does the rod stick to the work?

Most often the current is too low or the arc is held too short when striking. Raise the current by 5–10 A and lift the rod as soon as it lights.

Rutile or basic for a gate?

Rutile. Basic rods are for loaded structures and harder-to-weld steels where crack resistance matters. For thick sections or higher-carbon steels, also check the required preheat.

Table values are indicative, compiled from rod manufacturers' data sheets and workshop practice. Always follow the instructions for your machine and rods. Links to MatHaus are affiliate links: if you buy through them, e-utilio.ro may earn a commission at no extra cost to you. Details.