Troubleshooting guide › Process troubleshooting › Welding carriage and automation problems

Welding carriage, oscillator and automation problems: uneven beads, wander, stops

A welding carriage does exactly what it is set up to do, for the whole seam. That is its strength and its weakness: a torch set 5 mm too high gives the same undercut for 6 metres. Most automation problems are set-up problems: torch position, speed, guide wheel, and the state of the plate. The electrical faults are few and easy to separate.

Seen with: Trackless fillet welding carriages, rail-guided trolleys, oscillators (weavers), pipe welding carriages, column-and-boom with MIG or SAW heads.

Reviewed by the Cruxweld technical team, October 2026. Settings are starting points to confirm on a test piece; acceptance is decided by the code or drawing the job is built to. Checks marked “call” are for our technical team.

Before you start: Switch off and isolate the machine before touching any cable, feeder or torch connection. Anything inside the cabinet is for our technical team, not the operator. Keep hands clear of the drive wheels and the oscillator arm while the carriage is powered.

Setting the torch correctly (the cause of most bead faults)

SettingTypical valueIf wrong you get
Torch angle between the plates (fillet)45 degrees, plus or minus 10Unequal legs; undercut on the vertical plate or overlap on the flat plate
Travel (lead) angle0-10 degrees dragToo much push: flat bead, spatter; too much drag: narrow, convex bead
Contact tip to work distance10-15 mm below 200 A, 15-20 mm at 200-350 A, 20-25 mm above 350 AToo long: porosity, cold bead; too short: burnback, nozzle spatter
Wire aimAt the root, 0-1 mm towards the flat plate for small legs; towards the vertical plate for legs over 8 mmLegs unequal; root not fused
Guide wheel / rollersBoth guide rollers touching the vertical plate, front one slightly behindCarriage drifts away from the seam
Oscillator (weave) for legs over 8 mmWidth 3-6 mm, 1-2 Hz, dwell 0.1-0.4 s each sideNo dwell: undercut at the edges; too wide: overlap and slag

Set the torch with the carriage on the job, run 100 mm, stop, and measure the legs with a fillet gauge. Adjust the X-Y slide, not the welding settings, until the legs are equal; then set the speed.

Speed and current for fillet leg size (1.2 mm wire, CO2)

PlateLegCurrentVoltageSpeedTip to work
6 mm4-5 mm270-300 A28-31 V60-70 cm/min13-18 mm
6 mm6 mm220-250 A25-27 V35-45 cm/min13-18 mm
8 mm5-7 mm270-300 A28-31 V55-60 cm/min13-18 mm
8 mm7-8 mm (with weave)260-300 A26-32 V25-35 cm/min15-20 mm
12 mm7-8 mm (with weave)260-300 A26-32 V25-35 cm/min15-20 mm
12 mm10 mm, 1.6 mm wire430-480 A38-42 V30-40 cm/min15-20 mm

Typical carriage settings for mild steel in the flat and horizontal position; confirm on a trial seam. A carriage runs steadily at speeds a hand welder cannot hold, which is where the metres-per-shift gain comes from.

Bead and seam faults

1Bead not uniform along the seam

Loose torch mount or guide wheel screws, spatter on the guide wheel or tyres, plate surface uneven or dirty, wire feed stuttering.

Fix: Tighten the mount and wheel screws; clean the wheels; grind scale and weld spatter off the travel path; service the feeder.

2Carriage wanders off the seam

Guide wheel not fixed, or set with the rollers not both touching; magnetic base weak on thin or non-magnetic plate; debris on the path.

Fix: Reset and lock the guide rollers; the carriage needs magnetic steel plate (holding force about 35 kg on a typical trackless carriage); clear the path before every run.

3Carriage stops mid-weld

Obstacle on the path (tack, spatter, clamp), deposit on the guide wheel, trigger cable pulled, over-temperature on the welding machine.

Fix: Clear the path; clean the wheel; support the cables; check the welding machine protection lamp.

4Porosity along the seam

Tip-to-work distance too long, gas nozzle full of spatter, draught along the seam, gas hose dragging and kinked.

Fix: Set 10-20 mm; clean the nozzle each run; screen the seam; support the hoses in a loop.

5Undercut on the vertical plate

Torch angled too far up, speed too high for the leg, current too high, no dwell on the weave.

Fix: Drop the torch angle a few degrees, slow down to the table, add dwell.

6Overlap on the flat plate

Torch aimed too low, speed too slow, voltage low.

Fix: Aim at the root; speed up; raise voltage one step.

7Crater at every stop, lump at every start

No crater fill or hot start on the welding machine; carriage stops before the arc.

Fix: Enable crater fill and hot start; set the carriage to stop the arc then travel on (most carriages have a stop-arc-then-move delay).

8Seam not straight (rail trolley)

Rail not parallel to the joint, rail joints misaligned, rail dirty.

Fix: Set the rail 75-100 mm from and parallel to the seam; clean rail joints; check with a straight edge.

Electrical and control faults

SymptomLikely causeWhat to do
Control box lamp offControl cable plug not seated, control fuse blown (usually 3 A), mains not onReseat the plug; replace the fuse once; if it blows again, call service
Carriage runs but no arcWelding-start relay cable not connected to the welding machine, trigger switch, slag on the wire endCheck the start cable to the machine remote socket; snip the wire end
Arc does not stop when stop is pressedWeld-off switch faulty, or the welding machine is in trigger-hold mode (4T / self-locking trigger), so it keeps the arc on after the carriage releases the triggerSet the welding machine trigger mode to 2T (hold-to-weld); replace the switch if it still does not stop. Never bypass a machine protection
Travel motor runs at one speed onlySpeed potentiometer faultyReplace the potentiometer
Travel motor does not run, lamp onMotor brushes worn, motor burnt, drive gear slippingCheck brushes; call service
X-Y slide stiffDry or dirty slideClean and add a drop of light oil
Wheel or motor hot (above 70 degrees C)Overload, drag, spatter in the bearingsStop and cool; find the drag

Oscillator (weaver) problems

  • Weave not centred on the joint: zero the oscillator with the arc off, over the root, before setting width.
  • Undercut at both edges: add dwell at each side (0.1-0.4 s) or reduce width.
  • Slag or cold lap in the middle: weave too wide for the current; reduce width or raise current.
  • Weave pattern ragged: speed too high for the frequency; a saw-tooth pattern at 1-2 Hz suits most fillets.
  • Oscillator stalls: arm fouling the plate or cables; mechanical binding.

Prevention checklist

  • Plate path cleaned of spatter, tacks ground flush, before every run.
  • Torch position checked with a fillet gauge after 100 mm on each new job.
  • Speed taken from the leg-size table, not guessed.
  • Guide wheel locked; both rollers touching.
  • Cables and hoses looped and supported, never dragging.
  • Crater fill and hot start on at the welding machine.
  • Guide wheel, tyres, tip and nozzle cleaned at every stop.

Questions we get asked

Will the carriage work on my MIG machine?

It needs a remote start input or a trigger connection, and a feeder that can sit near the carriage. Most industrial MIG machines qualify; our team checks the connection for your model before supply.

Why does the hand weld look better than the carriage weld?

Because the carriage was set up by eye and the hand welder adjusts continuously. Once the torch position and speed are set from a measured test, the carriage bead is more consistent than any hand weld and stays that way for the whole shift.

How much faster is it really?

A hand welder on a 6 mm fillet manages about 25-35 cm/min with breaks; the carriage holds 35-45 cm/min without them. The cost calculator shows metres per shift and rupees per metre for your own numbers; a trial on your job confirms them.

Fix it yourself: your Cruxweld machine

Lamps, fault codes and the checks an operator can do outside the cabinet, for the machines this page applies to.

Does the machine matter?

A carriage needs a welding machine with a remote start/stop or torch trigger input, enough duty cycle for continuous welding (the carriage never pauses), and for MIG a feeder close to the carriage so the torch cable is short. Our automation range is matched to our MIG and SAW machines for this reason. A trial on your own job, with your plate and leg size, confirms the result before you commit.

Still stuck?

Send a photo of the weld or cut, your machine model, consumable and plate thickness. Our technical team replies on WhatsApp with the likely causes and the next checks to make.

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