39J1844-403 44 mm NEMA16 Stepper Motor - 0.29 N·m

The 39J1844-403 is a 44 mm NEMA16 Stepper Motor built in the 39 mm intermediate frame, rated 0.29 N·m at a low 0.3 A with a 5 mm shaft. It fills the gap between micro NEMA8/11 motors and the more common NEMA17, offering more torque than micro steppers while staying lighter and more compact than most NEMA17 variants.

An Intermediate Step Between Micro and Standard Frames

Designers choose NEMA16 when a NEMA17 is too bulky but a micro stepper lacks output. The 39 mm frame provides enough stack to produce 0.29 N·m while keeping the whole assembly light enough for gimbals, translation stages, and portable instruments. The 0.3 A current is among the lowest in its torque class, which keeps the thermal footprint small in enclosed housings.

Specification

• Frame: NEMA16 (39 mm)
• Body length: 44 mm
• Phase current: 0.3 A
• Holding torque: 0.29 N·m
• Shaft: 5 mm
• Type: 2-phase, open-loop

Laboratory and Optical Mechanisms

Optics-based instruments rely on precise, low-vibration stepping to position lenses and filters. The motor’s repeatable micro-steps support fine positioning where sub-millimeter travel and stability are required, such as autofocus stages, filter wheels, and sample translation. Precision automation equipment uses the same characteristics to move small carriages and probes along short rails.

Design Notes

The 5 mm shaft and standard NEMA16 pattern ease mounting and coupling in compact instrument designs. Because the motor draws only 0.3 A, it pairs well with low-power drivers and small supplies, and it can be run continuously in bench-top and handheld devices without significant heat build-up. For applications that need a middle-ground frame with quiet, precise open-loop control, the 39J1844-403 is a practical choice. For engineers weighing a frame size, the NEMA16 mounting preserves the small envelope while the 44 mm stack gives enough output for filter wheels, focus drives, and sample indexing without stepping up to a heavier NEMA17.