What is Step Motor Stack Length?

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What is Step Motor Stack Length?

In our post What Do NEMA Sizes Mean?, we examined the NEMA frame sizes in which step motors are made. Larger frame sizes produce more torque. But this is not a one dimensional process: within a given frame size, the motor length can vary and that also affects torque. Because step motors require expensive tooling in order to be produced economically, a fixed rotor length is chosen, as is the stator that surrounds it.

step motor diagram

In the next photo, a single stack rotor, with bearings, is shown.

step motor rotor

To produce longer, more powerful motors, multiple rotors and stators are “stacked up”. The NEMA 17 motors below incorporate one, two, three and four stacks.

NEMA 17 step motors

The chart below shows the holding torque (in Newton-meters) for motors of varying frame size and stack length. This allows engineers flexibility in matching a motor to an application. Sometimes there is available space for a longer motor and other times it is advantageous to use a shorter motor with a larger frame size. High quality step motors are available in many frame sizes and stack lengths and with other options like encoder feedback, IP65 harsh environment ratings and shielded cables.

Holding Torque (N-m)
Frame Size One stack Two stacks Three stacks Four stacks
NEMA 11 0.05 0.11 N/A N/A
NEMA 17 0.22 0.37 0.55 0.80
NEMA 23 0.54 1.12 1.90 2.50
NEMA 24 0.87 1.25 2.50 N/A
NEMA 34 2.80 6.00 8.90 11.96

Just for fun, we plotted the relationship of stack length and frame size on a 3D chart.

step motor torque

Cloudray stepper motor factory video

Cloudray Stepper Motor Series has set the standard for quality, reliability, and durability in stepping motors. The precision of our Torque Power motors is matched only by the dependability of their performance. All Torque Power motors are bi-directional and totally enclosed with permanently lubricated ball bearings for long-lasting, smooth operation.

laser printer stepper motor 2-Phase
High Torque, High Precision and Long life is Cloudray's core advantages
Low vibration,Low heating, No loss of step
Fast Response,Better Acceleration Performance
Thanks to a robust design they can be selected for the harshest environments. Precise, open-loop, speed and position control can be achieved with the application of full step, half step, or microstepping electronics.
laser printer stepper motor 2-Phase
Higher Resolution,Avoidance of Resonance Regions
Stepping angle is adjustable( rang in 18°±5%), 0.9 °stepper motor's stepping angle is smaller, fineness is higher and positioning is more accurate.Avoiding vibration,runs more smoothly and gets lower noise.
laser printer stepper motor 2-Phase
Sturdy structure, extremely long life
High quality materials including bearings and shaft made in Japan
Robust assembly, high speed range, and exceptional performance in even the harshest environments make Cloudray Stepper Motors the perfect solution for demanding positioning applications.
laser printer stepper motor 2-Phase
Short length and light weight allow them to be used in highly integrated systems
laser printer stepper motor 2-Phase


laser printer stepper motor 2-Phase
laser printer stepper motor 2-Phase
laser printer stepper motor 2-Phase
Stepper motor application
Cloudray stepper motor and Stepping Motor Driver are widely used in engraving machine, cutting plotter, textile machine, 3D printer, medical devices,stage lighting equipment, robot, CNC machine, music fountain and other industrial automatic equipment.
laser printer stepper motor 2-Phase
laser printer stepper motor 2-Phase
laser printer stepper motor 2-Phase

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