LN-25X Field Guide

The feeder

The suitcase, inside and out

Tap any part for a plain-English answer. Inside, hold Cold feed to watch the wire move. When you think you know them, hit Quiz me.

Drag the knobs or use the sliders. The test bead below updates as you turn.

Wire feed speed

Voltage

Your travel speed

SlowFast

Test beadDialed in

Cold

Hot

Teaching model: here the middle of both knobs is balanced. Real balance depends on your wire size and type, so go by the spool label or your WPS.

Trigger modes

2-step vs 4-step

There's no 3-step. The switch inside the door picks 2-step or 4-step. Pick a mode, then press and hold the trigger to see what the feeder does at each step.

Gas

Wire

Arc

Ready

Press and hold the trigger.

Remember it

Behind the door

Inside settings cheat sheet

Setting	What it does	Starting point / tip
Pressure arm	How hard the drive rolls squeeze the wire. It has a number scale.	Lincoln's manual: solid steel or stainless 4–6, cored (flux-core) 3–4. Cored wire is softer, so less squeeze.
Spindle brake	Drag on the spool.	Just enough that the spool stops when the wire stops. Like the drag on a reel.
2-step / 4-step switch	Trigger mode.	2-step for tacks and short welds. 4-step for long beads.
Cold feed / gas purge	Feeds wire or flows gas without turning on weld power.	Cold feed when loading wire. Purge when setting gas flow.
Run-in speed	How fast the wire creeps in before the arc lights.	Slower run-in gives softer starts.
Pre-flow / post-flow	Gas before the arc starts and after it stops.	Post-flow covers the hot crater so it doesn't get porous.
Burnback	Keeps the arc on a split second after the wire stops so the wire doesn't stick in the puddle.	Set too long, it melts the wire back into the tip. Getting a ball welded on the tip? Have whoever sets up the machine check this.
Thermal light	The drive motor got too hot. It shuts the drive off for up to about 30 seconds to cool.	If it keeps happening, look for drag: dirty liner, kinked cable, tension too high.
Trigger at power-up	If you're holding the trigger when the feeder powers up, it won't feed.	Let go of the trigger, then pull again.

Run-in, pre-flow, post-flow, and burnback are set through the setup menu on most units. Check your manual or your lead before changing them.

Know the names

The whole gun

Tap a part to see what it does and what goes wrong with it. The liner is the dashed line running inside the cable.

Zoomed in

Front of the gun

Inside the case

Feeder parts, spool to gun

Spool & spindleHolds the wire. The spindle brake keeps the spool from free-spinning when you let off the trigger. Retainer locks it on.

Inlet guideThe tube the wire enters before it reaches the drive rolls.

Drive rollsGrooved wheels that push the wire. Size is stamped on the roll. V-groove for solid, knurled for flux-core.

Pressure armTension knob that squeezes the rolls onto the wire. Too loose slips, too tight crushes.

Gun bushingWhere the gun plugs in. Push it all the way in and lock it, or wire and gas feed badly.

Cold feedFeeds wire with no power and no gas. Use it to load wire.

Gas purgeFlows gas with no wire so you can set flow and clear the line.

2-step / 4-step2-step: hold trigger to weld. 4-step: click on, click off.

LinerTube inside the gun cable that the wire rides through. Dirty or kinked liners cause stutter and burnback.

Angles & motion

Holding the gun

If there's slag, you dragFlux-core leaves slag, so drag it like stick. Solid wire with gas, push it.

Bacon, not popcornA good wire arc sizzles steady. Pops and crackles mean your settings are off.

Clip, then weldSnip the ball off the wire before every start.

Firm handshakeRoll tension: tight enough that it doesn't slip, not so tight it crushes.

Stick habits hold the arc too tight and drag everything. Set the process, then move the sliders to see how the angle and distance should look.

Travel angle

Nozzle-to-work distance

Cursive "e" motion

How to run it

Loops about the width of the bead, 1/4" or less.
Pause a split second on each toe so it wets in. The dots show where.
Move quicker through the middle so it doesn't pile up.
Keep the rhythm even. Consistent spacing matters more than loop size.

Work angle: about 45° into a fillet, 90° on a flat butt, slightly up toward the top plate on horizontal.

Practice without burning wire

Dial it in

Move the sliders and watch the bead lay down. Tap a mistake to see what it looks like, then hit Play to hear it.

Wire = heat. Volts = width.Wire speed sets your amps. Volts set how long and wide the arc is. Keep them balanced: when one goes up, the other usually follows.

What if...?

Tap a box. It sets the sliders below and tells you what you'd see, hear, and feel.

Wire speed

SlowFast

Voltage

LowHigh

Gun distance

CloseFar

Travel speed

SlowFast

This is a teaching model, not real numbers. Real settings come from the spool label, your WPS, or a test bead on scrap.

How much heat

Heat chart

Pick your metal thickness and wire size. It works out a starting amperage and wire speed, and shows the math so you can do it in your head next time.

Metal thickness (steel)

Wire size

Remember it

Do it in your head

One amp per thouEvery 0.001" of steel takes about 1 amp. 1/8" is 0.125", so about 125 amps.

.045 is one-for-oneWith .045 wire, wire speed in inches per minute is about the same number as your amps.

Skinny wire, fast feed.035 × 1.6, .030 × 2, .023 × 3.5. Thinner wire has to move faster to carry the same amps.

Floor, ceiling, middleDrop volts until the wire stubs. Raise them until the arc goes wild. Weld halfway between.

Fractions to thou

Thou = thousandths of an inch = your amps.

16 ga≈ .060"

14 ga≈ .075"

1/8".125"

3/16".188"

1/4".250"

3/8".375"

1/2".500"

Starting points for solid wire on steel, from Miller's MIG rules of thumb. Flux-core runs differently, so go by its spool label. Always run a test bead on scrap first.

Wire	Gun motion	Polarity	Stickout	Shielding
Solid (hardwire)	Push, 10–15°	DCEP	3/8"–1/2"	Gas, about 20–30 CFH. Screen it from wind.
Self-shielded flux-core	Drag, 10–15°	Usually DCEN. Check the spool label.	About 3/4"	From the flux. Better outside.

LN-25X Field Guide

The suitcase, inside and out

2-step vs 4-step

Inside settings cheat sheet

The whole gun

Front of the gun

Feeder parts, spool to gun

Load a spool, step by step

Holding the gun

Cursive "e" motion

How to run it

Dial it in

What if...?

Heat chart

Metal thickness (steel)

Wire size

Do it in your head

Fractions to thou

Troubleshoot

Pre-weld check