LDO Motor Selection Guide

LDO Motor: Collection List 

You cannot find suitable one? Contact us for special order/sample to suit your application/usage.

Stepper Motor Terminology:

Step Angle: The portion of a 360-degree rotation completed with each full step. Motors with 1.8 degrees per step require 200 steps for a full revolution, while motors with 0.9 degrees per step require 400 steps. Smaller step angles provide more precise motion. 

Voltage: The reference voltage needed to achieve maximum current with the specified resistance. This is generally not relevant when using chopping stepper drivers, as in most 3D printers. 

Current: The maximum recommended continuous (RMS) current per coil. 

Resistance: The rated resistance per coil. (For troubleshooting - You can measure resistant per pair to double check motor specification)

Inductance: The motor's resistance to changes in current. Higher inductance requires the stepper driver to work harder to change direction or speed. Lower inductance allows the motor to respond faster, enhancing acceleration and reducing EMF for higher maximum speeds. 

Holding Torque: The maximum torque the motor can exert while powered; higher values are preferable. 

Detent Torque: The torque present when the motor is not energised. 

# of leads: The number of wires needed to connect and operate the motor. 

Weight: Lighter motors are preferable if they are mounted on a moving axis. 

Winding Temp: The maximum temperature the motor windings can withstand before sustaining damage. 

Stepper selection recommendations:

XY Axis

For optimal motion control, a motor with a small step angle is recommended. However, users with 8-bit controllers might encounter limitations with step pulse generation on particularly fast machines and advanced geometries like delta or coreXY, leading to slower maximum speeds. If your machine's axes carry other motors, selecting lighter motors can help maintain high acceleration.

• Simple: 42STH48-1684AC
• High Resolution: 42STH60-2004MAC
• High Speed: 42STH48-2504 (AH/AC)
• High Speed/High Voltage: 42STH48-2804 (AH/AC)

Z Axis

Z-axis motors are usually stationary, so they don't need to be lightweight. Depending on your leadscrew's lead (rise per revolution), a motor with a larger step angle (1.8 degrees per step) may be sufficient. For example, a single-start 2mm pitch leadscrew driven by a 1.8-degree step motor pairs one step with 0.01mm of motion, ensuring excellent z-axis repeatability at any layer height.

Machines with a quad-start 2mm pitch leadscrew and a 1.8-degree step motor may require layer heights to be multiples of the step length (0.04mm/step). If commanded to a non-multiple layer height (e.g., 0.3mm), the motor may lock into a full step (0.28 or 0.32mm), causing inconsistent extrusion. Switching to a 0.9-degree step motor reduces the step length to 0.02mm, minimising these artifacts.

Consider the risk of back-driving and height loss when unpowered, especially on belt-lifted Z axes, which lack the mechanical advantage of leadscrews and may rely solely on motor output.

• Recommended: 42STH40-1684AC or LDO-42STH48-2004AC(VRN)

Extruder:

Extruder motors don't need to be the strongest on the machine. In direct-drive configurations, the head's mass is a crucial factor once sufficient torque is achieved.

• 42STH40-1004ASR or 42STH40-1004ASH: Provides more torque (4.8 kg-cm) but is larger (40mm long) and heavier (0.28 kg).
• 42STH25-1404MAC: Offers less torque (1.8 kg-cm) but is smaller (26mm long) and lighter (0.15 kg).

For direct-drive systems, the 1404MAC might be preferable to reduce the moving mass. For Bowden systems, the motor's mass isn't as critical, so the higher torque of the 1004ASR can be beneficial.

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