Miller Maxstar 350

Miller Maxstar 350 Overview

What the machine does

The Miller Maxstar 350 is a DC inverter TIG and Stick welding power source built for shops and applications that demand a smooth, precise arc — precision metal fabrication, tube mills, pipe and tube fabrication, tool and die work, exotic material fabrication and pressure vessel fabrication.

Unlike Miller’s engine-driven Bobcat line, the Maxstar 350 runs on shop power rather than a gas or diesel engine, and it carries no built-in generator function. It’s a precision inverter, not a jobsite power source.

Why buyers pick the Maxstar 350

One design choice defines the machine: it accepts any input voltage from 208 to 575 V, single- or three-phase, with no manual linking required, which Miller markets as an ideal solution for dirty or unreliable power. That flexibility lets one machine move between facilities and power setups without rewiring.

Compared with the earlier Maxstar generation, the 350 offers high-speed pulsing up to 5,000 pulses per second — a tenfold improvement — along with 50 amps more welding power and Auto-Line power management.

Models and packages

Miller sells the Maxstar 350 as a bare power source and in several packaged configurations. These include the standard Maxstar 350, a 380–575 VAC international version, a version with an automation interface, the Maxstar 350 TIGRunner, and the Maxstar 350 Complete with wireless remote foot control. It’s also offered as a TIGRunner package with the Coolmate 3.5 cooler, and as a package including that cooler with a Weldcraft water-cooled torch.

Miller Maxstar 350 Specifications

Warranty

The power source is warranted for 3 years, parts and labor.

Miller Maxstar 350 Features

• Blue Lightning high-frequency arc starter for non-contact arc initiation, giving more consistent arc starts than traditional HF starters.
• Hot Start adaptive control provides positive arc starts without sticking.
• Nine independent program memories maintain and save welding parameters.
• Auto-postflow adjusts postflow time automatically based on the amperage setting, protecting the tungsten without manual adjustment.
• A 120-volt auxiliary power receptacle powers a cooling system.
• Meter calibration lets the digital meters be calibrated for certification work.
• Fan-on-demand and sequence control round out the digital control set, along with last-procedure recall and Lift-Arc starting.

Miller Maxstar 350 Welding Output

TIG (GTAW and Pulsed TIG)

The machine is built as a precision DC TIG source. It provides an exceptionally smooth and precise arc suited to welding exotic materials, and its high-speed pulsing lets operators fine-tune puddle control on thin or heat-sensitive material.

Stick (SMAW)

Hot Start adaptive control gives clean, non-sticking Stick starts across the machine’s amperage range.

Air Carbon Arc Gouging

The Maxstar 350 gouges with carbons up to 1/4 inch, smaller than the 3/8-inch capacity of its larger sibling, the Maxstar 700.

Power Source and Portability

Auto-Line input power

Auto-Line is an internal inverter circuit that automatically links the power source to any primary input voltage from 190 to 625 volts, single- or three-phase, at 50 or 60 hertz, and adjusts for voltage spikes across that range. That range covers nearly any shop or industrial power drop without a technician manually rewiring the input.

Weight and footprint

At 135 lb (61 kg), the Maxstar 350 is light enough to hand-carry between stations, and Miller offers a four-wheel cart runner alongside TIGRunner packages for shops that move the machine regularly.

Miller Maxstar 350 Manual

Finding the right version

Miller publishes owner’s manuals free at millerwelds.com, indexed by serial number. Because the Maxstar 350 has gone through revisions since its introduction, check the rating plate on the unit before pulling a manual — wiring diagrams and control-panel layouts can differ between production runs.

Sections operators use most

The manual’s most-used sections cover control panel functions (memory recall, pulser settings, Hot Start adjustment), input power and Auto-Line operation, and troubleshooting for arc starting or output issues. Since the Maxstar 350 has no internal combustion engine, there’s no engine-service chapter to consult — maintenance is limited to the electrical and cooling systems.

Miller Maxstar 350 FAQs

What processes does the Maxstar 350 run?
TIG (GTAW), Pulsed TIG (GTAW-P), Stick (SMAW), and air carbon arc gouging up to 1/4 inch.

What’s the amperage range?
3 to 350 amps, with a rated output of 300 A at 32 V on a 60% duty cycle.

What input power does it need?
208 to 575 volts, single- or three-phase power, handled automatically by Auto-Line.

How much does it weigh?
135 lb (61 kg).

Does it have a generator?
No. Unlike Miller’s engine-driven Bobcat welder/generators, the Maxstar 350 is a shop-power inverter with no onboard generator.

What’s the warranty?
Three years, parts and labor, on the power source.

How does it compare to the Maxstar 700?
The 700 scales up to 600 A at 44 V on a 60% duty cycle and gouges up to 3/8-inch carbons, at roughly 198 lb (90 kg) versus the 350’s 135 lb — the 350 suits lighter, more portable precision work, while the 700 targets heavier fabrication.