NEMA 17 17HS4401S stepper motor with 350 mm integrated TR8×8 lead screw

NEMA 17 17HS4401S bipolar stepper motor with an integrated 350 mm TR8×8 trapezoidal lead screw. It is intended for direct linear motion in Z axes, actuators and DIY machines without a coupling between the motor and the lead screw.

The lead screw forms part of the motor shaft, simplifying the assembly and avoiding errors caused by a poorly centred coupling. Correct alignment is still essential: the motor, screw, nut and linear guide must share the same axis, and an integrated screw does not remove nut backlash.

Mechanical specifications

The stated length is the commercial nominal lead screw length, not a guaranteed usable travel. Available movement also depends on the nut position, brackets, end geometry and safety margins.

Choosing the cable and nut

• DuPont 4P or XH2.54: select the termination required by the controller or installation. A matching housing does not guarantee a matching pinout.
• Brass nut: a rigid metal option with good wear resistance. Suitable lubrication may be required and friction and noise depend on load and alignment.
• POM nut: provides low-friction contact and may run more quietly. It is not a universal upgrade; load, temperature, speed and maintenance must be considered.

Both nuts must be specifically TR8×8. T8×2 and T8×4 nuts may share the nominal 8 mm diameter but not the thread geometry or lead.

The reference drawing shows a Ø22 mm flange, an approximately Ø10.2 mm body, four Ø3.5 mm holes on a Ø16 mm bolt circle, a 3.5 mm flange thickness and a 10 mm body. Check the received nut before machining a close-tolerance housing.

Compatibility

Suitable for RepRap printers, Prusa i3-derived designs, small CNC machines, actuators and automation equipment when the machine is designed or adapted for a NEMA 17 motor with an integrated TR8×8 lead screw of this length. Before replacing a motor, verify:

• NEMA 17 mounting and space for an approximately 40 mm motor body.
• Lead screw length, required travel and clearance at both ends.
• TR8×8 specification: nominal Ø8 mm, 2 mm pitch, four starts and 8 mm lead.
• Nut geometry and mounting.
• Connector, coil order and driver capability.
• Firmware steps per millimetre, speed, acceleration and direction.

Do not treat it as a direct replacement for a specific Original Prusa model without checking the exact motor reference, length, connector and electrical characteristics. Creality Ender-3, CR-10 and other machines that use a conventional motor connected to a separate lead screw through a coupling require mechanical modifications.

Voron Trident: it uses three Z motors with integrated lead screws, but its commonly documented configuration uses T8×4 screws with 4 mm lead. This TR8×8 motor is not a direct replacement. It may only be used in a coordinated conversion where all three Z drives, nuts and firmware are changed together. Never mix T8×4 and T8×8 drives on the same Z axis. Voron 2.4 uses belt-driven Z reductions, so this motor does not match its original system.

Steps per millimetre

For a 1.8° motor and a TR8×8 lead screw, the theoretical calculation is: 200 steps per revolution × microsteps ÷ 8 mm per revolution.

Marlin, Klipper and RepRapFirmware configuration

Marlin

Configure Z in DEFAULT_AXIS_STEPS_PER_UNIT when compiling or with M92. Starting values are M92 Z400 at 1/16 or M92 Z800 at 1/32. Check the active value before moving the axis and use M500 only when EEPROM is enabled and the setting should be saved.

Klipper

For direct drive, use rotation_distance: 8, full_steps_per_rotation: 200 and set the driver's actual microsteps. Do not add a gear_ratio unless the machine includes an additional reduction.

RepRapFirmware

Set microstepping with M350 before setting steps per millimetre with M92. An example at 1/16 is M350 Z16 I1 followed by M92 Z400. If several motors form one Z axis, all of them must use equivalent mechanical transmission.

There is no universal driver-current value. It must be set from the electrical specification of the installed unit and the controller capability. Do not copy a value from another motor simply because it is also NEMA 17.

Installation and first test

1. Fully power off the machine before connecting or disconnecting the motor.
2. Use a multimeter to identify the two coil pairs. Wire colours and connector type do not guarantee the same order between manufacturers.
3. Position the motor, nut and guide without forcing the screw; tighten the assembly after alignment.
4. Configure TR8×8 lead, conservative Z speed and safe travel limits.
5. With the load protected, test a short movement and verify direction before homing.
6. Measure a known movement and only correct the configuration after confirming the mechanics and microstepping.

Never connect or disconnect the motor while the driver is powered, as this may damage the controller. Do not run the nut against the motor or the end of the lead screw.

Other lengths and replacement parts

• NEMA 17 17HS4401S motor with 300 mm TR8×8 lead screw.
• NEMA 17 17HS4401S motor with 310 mm TR8×8 lead screw.
• Separate TR8×8 lead screw with selectable length and nut, for motor-and-coupling assemblies.
• T8×8 flanged Brass nut.
• T8×8 flanged POM nut.

A separate lead screw is not automatically equivalent to this integrated assembly: it requires a motor with the correct shaft, a compatible coupling and proper alignment.

Package contents

• 1 NEMA 17 17HS4401S motor with integrated 350 mm TR8×8 lead screw.
• 1 m cable with the selected termination.
• 1 flanged TR8×8 Brass or POM nut according to the selected option.