HTA3D Direct Extruder for P3Steel, Flexible Filament, MK8 and V6 Hotend

A direct extruder designed by HTA3D for the HTA3D P3Steel and projects based on the classic Prusa i3 architecture. It combines an MK8 drive for 1.75 mm filament, a close-fitting filament guide and an all-metal V6 hotend. It is a simple, proven solution for maintaining a P3Steel or upgrading an older printer whose extruder leaves excessive unsupported space around the filament.

What this design provides

• Short, guided path: the PTFE tube supports the filament almost up to the drive gear, reducing the open space in which a flexible material can buckle.
• Simple MK8 drive: one stainless-steel hobbed gear pushes the filament against an adjustable 623ZZ idler bearing.
• All-metal V6 hotend: a familiar format with a 40 W heater and 3010 heatsink fan.
• P3Steel spare: keeps an HTA3D machine running without necessarily replacing the complete X carriage.
• Adaptable to older machines: it can be used on certain Prusa i3 Rework, Wilson and related printers —including some older Anet derivatives— when the carriage fits or is replaced with a suitable mount.

Technical specifications

Compatibility and installation

This is the extruder used by the HTA3D P3Steel. On another printer, the Prusa i3 name or the presence of smooth rods does not guarantee compatibility: check the four-screw carriage pattern, rod spacing and diameter, nozzle position, usable travel, cooling, endstops and motor clearance.

An older machine may need a printed or replacement X carriage, a different part-cooling duct, rewiring and firmware changes. Carrying the motor on the carriage improves the filament path but adds moving mass; review acceleration, speed and resonance compensation where applicable.

Extruder calibration

The listed values are starting points for the included 1.8° motor, not final calibration. Mark the filament, request a slow extrusion with the hotend at a suitable temperature, measure the actual movement and correct it. For steps/mm: new value = previous value × requested distance / actual distance.

Marlin

M92 E152
M500

The example is for 1/16 microstepping; the historical 1/32 starting value is 304 steps/mm. M500 only stores it when EEPROM is enabled.

Klipper

[extruder]
full_steps_per_rotation: 200
microsteps: 16
rotation_distance: 21.05

Then measure actual extrusion and use: new rotation_distance = previous × actual distance / requested distance. Do not add a gear_ratio; this extruder has no reduction gearing.

RepRapFirmware

Select the drive microstepping with M350 and configure its steps/mm with M92; 152 steps/mm at 1/16 is only a starting point. Adapt the drive number and exact command to the controller and firmware version.

Temperature sensor and safety

A generic 100K NTC Beta 3950 normally uses table 11 in Marlin, sensor_type: Generic 3950 in Klipper or a 100K/B3950 NTC configuration in RepRapFirmware. If the supplied sensor has a clearly identified different reference, that reference takes priority.

Historical documentation states a 300 °C assembly limit, constrained by the sensor. Never configure above the lowest-rated component. Before heating, confirm heater and fan voltage, a plausible ambient reading, continuous heatsink cooling and active thermal protection.

Using flexible filament

The close guide removes a common buckling point, but does not make every flexible filament effortless. Let the spool unwind freely, use moderate speed and flow, avoid excessive retraction and set enough idler pressure to grip without crushing the material. Hardness, moisture, temperature and actual filament diameter still matter.

Contents

• All-metal V6 hotend with 40 W heater, 100K NTC thermistor and 3010 fan.
• 40 mm NEMA 17 motor.
• Printed extruder parts.
• 1.75 mm MK8 hobbed gear and 623ZZ bearing.
• Mounting hardware: 4 M4×25; 1 M3×35 with spring and washers; 4 M3×30; 2 M3×25; 1 M3×16; 3 M3×12; 2 M3×8; 1 M3×10 stud; 4 M4 nuts and 1 M3 nut.

The X carriage, part-cooling fan and cable chain shown in some photographs are installation examples and are not considered included unless the selected option explicitly says otherwise.

Original or V2?

Choose this version when restoring a P3Steel or when you prefer a simple MK8 mechanism. For dual drive, integrated 3DTouch, filament sensor and part cooling, see the HTA3D V2 extruder for 3DSteel.

It is for you if

• You want to maintain or restore an HTA3D P3Steel.
• You need a direct, guided path for more reliable flexible-filament feeding.
• You can verify or adapt the carriage, wiring and firmware of a Prusa i3 derivative.

It is not for you if

• You need a universal drop-in replacement without measuring or firmware changes.
• You want dual drive, tactile levelling and a filament sensor already integrated.
• Your overriding priority is minimum X-axis mass through Bowden or a newer lightweight extruder.