Wade-L3K Greg's Wade-style extruder with 4.3:1 reduction — mechanical kit

The Wade-L3K is a geared direct extruder based on the Greg's Wade architecture and developed for Prusa i3 printers and RepRap projects. A NEMA 17 motor drives a 10-tooth pinion meshing with a 43-tooth gear, providing a nominal 4.3:1 reduction.

Filament is driven by an M8 hobbed bolt and pressed against it by a spring-loaded 608ZZ bearing. The body guides the filament close to the contact point, reducing its unsupported length. This is particularly useful when testing flexible filament, although actual performance depends on material hardness, hotend and calibration.

Important: the motor, hotend and X carriage are not part of the base kit. Photographs show assembled examples and optional components; supplied contents depend on the option selected.

How the Wade-L3K transmission works

• Motor pinion: 10 teeth.
• Hobbed-bolt gear: 43 teeth.
• Reduction: 43:10 or 4.3:1.
• Drive shaft: M8 hobbed bolt supported by two 608ZZ bearings.
• Pressure: a third 608ZZ bearing in a hinged idler, adjusted by two sprung screws.

The reduction multiplies available torque at the hobbed bolt and enables fine feed control. In exchange, the assembly is larger and heavier than a modern direct extruder, making it particularly suitable for classic RepRap and Prusa i3 rebuilds where open, repairable mechanics are valued.

Base kit contents

Printed parts

• 1 extruder body.
• 1 hotend retaining flange.
• 1 hinged idler.
• 1 43-tooth large gear.
• 1 10-tooth pinion.

Bearings and fasteners

• 3 × 608ZZ bearings.
• 1 × M8 hobbed bolt.
• 3 × M8 washers and 1 × M8 self-locking nut.
• 1 × M8 × 20 mm set screw for the idler bearing axle.
• 2 × M3 × 40 mm screws, 4 × M3 washers, 2 × M3 nuts and 2 springs for pressure adjustment.
• 3 × M3 × 25 mm screws and 3 × M3 nuts for assembly.
• 1 × M3 × 5 mm set screw and 1 × M3 nut for pinion retention.

Available options

• With X-axis carriage: adds the printed carriage, 4 × M4 × 25 mm screws and 4 × M4 nuts.
• Assembled: the included mechanical assembly is supplied assembled. It does not add a motor, hotend or electronics.

Check the option shown in the basket before completing your order. Printed-part colour may vary according to availability; green and black photographs are examples.

Not included

• NEMA 17 stepper motor and cable.
• Hotend, nozzle, heater and temperature sensor.
• Cooling fans or ducts.
• X carriage unless explicitly selected.
• Linear bearings, belts, pulleys, controller board and stepper driver.

Filament and hotend compatibility

The open Wade-L3K project provides different bodies and flanges for 1.75 and 3 mm filament. They are not one universal part. A diameter option is not identified in the current selector, so please ask us to confirm the required version before ordering when this is critical.

The flange is intended for hotends whose mounting geometry matches the seat in the body. An all-metal construction does not establish compatibility: diameter, groove, height, filament path and available space must all match. The supplied body must also correspond to the filament diameter in use.

3D-printer compatibility

The design originated for the Prusa i3 and RepRap family, but it is not a drop-in replacement for every variant. An adaptation requires checking:

• carriage mounting pattern;
• X-axis rod spacing and diameter;
• linear-bearing format and position;
• belt line, motor volume and possible collisions;
• final hotend height and usable Z travel.

The optional carriage belongs to this L3K implementation and is not universal for every Prusa i3, P3Steel or clone. Compare dimensions and mounting orientation before replacing an existing extruder.

Motor and mechanical adjustment

A NEMA 17 motor matching the pinion shaft, mounting pattern, available length and printer electronics is required. Our 17HS4401 NEMA 17 motor may be considered as a candidate, but shaft, wiring, current and clearance must be checked before installation.

1. Align the 10-tooth pinion with the large gear without applying a side load to the hobbed bolt.
2. Adjust motor distance for free meshing without excessive backlash or tight spots.
3. Tighten the M8 nut only enough to remove axial play while retaining smooth rotation.
4. Centre the hobbed section on the filament path.
5. Balance both springs: excessive pressure deforms filament and loads the motor; insufficient pressure causes slipping.

Marlin, Klipper and RepRapFirmware setup

There is no universal steps-per-millimetre value. In addition to the 43:10 reduction, the motor, effective microstepping and effective hobbed-bolt diameter all affect calibration. Calibrate with the hotend heated, at low speed and without slipping.

Marlin

Read the current value using M92 or M503. Request a known distance, measure actual feed and calculate:

new steps = current steps × requested distance ÷ actual distance

Apply with M92 E<value> and, when EEPROM is enabled, save with M500. Do not copy another Wade's value: effective hobbed-bolt diameters may differ.

Klipper

[extruder]
gear_ratio: 43:10
rotation_distance: <calibrated value>

An initial rotation_distance can be estimated from the effective hobbed-bolt circumference: effective diameter × π. Then correct it using:

new rotation_distance = previous value × actual distance ÷ requested distance

Do not multiply or divide by 4.3 again inside rotation_distance when gear_ratio: 43:10 is already declared.

RepRapFirmware

Configure effective microstepping with M350 where applicable and set extruder steps per millimetre using M92 E<steps_per_mm>. Store the final value in config.g. Motor current is selected for the installed NEMA 17 and driver, not from the L3K name.

After feed calibration, tune flow, retraction and Pressure Advance or Linear Advance for each material. The reduction is not a reason to use long retractions or aggressive speeds without testing.

This extruder is for you if

• You are repairing or building a classic Prusa i3 or RepRap.
• You want open, robust and maintainable mechanics using standard components.
• You need adjustable pressure and short guidance for testing flexible filaments.
• You can check dimensions and calibrate the extruder on your machine.

This extruder is not for you if

• You need a drop-in replacement for a modern printer without adapting the carriage.
• Your priority is minimum toolhead mass for very high acceleration.
• You cannot confirm filament diameter, hotend flange or motor fit.
• You need the motor and hotend included in a ready-to-connect assembly.

Open design

Wade-L3K is an open project with CAD and STL files published under the GPL v3 licence. See the original Wade-L3K GitHub repository to study the parts and adapt the installation.