- Stock: 18
- Model: Dual-Gears-5mm-ID
Quality
Inox Basic
Precision Hardened Steel (Recommended)
Dual-drive gear set for a 1.75 mm filament extruder, comprising a primary gear for a 5 mm motor shaft and a secondary gear supported by two needle bearings. Both sides grip the filament and rotate in sync, improving force transfer and reducing slip compared with a single drive gear.
Its geometry is Bondtech-style and corresponds to the format used by certain Original Prusa i3 MK2.5 and MK3 extruders. This is a replacement gear set: dimensions, secondary-shaft housing and filament-path alignment must be checked before installation.
Features
- Dual drive: the filament is gripped from both sides.
- Designed for 1.75 mm filament.
- Primary gear for a 5 mm motor shaft.
- M3 grub screw secures the primary gear.
- Secondary gear with two needle bearings and a 3 mm shaft.
- Declared material: stainless steel.
No stainless-steel grade, hardening process or surface treatment is specified for this set. For frequent use with highly abrasive filament, consider the Trianglelab hardened nickel-plated steel gear set.
Primary gear dimensions
| Dimension | Nominal value | Purpose |
|---|---|---|
| Overall length | 14.0 mm | Check available axial space. |
| Body diameter | Ø8.0 mm | Cylindrical gear body. |
| External gear diameter | Ø9.5 mm | Synchronises with the secondary gear. |
| Maximum external gear width | 4.0 mm | Check axial alignment. |
| Motor-shaft bore | Ø5.0 mm | For a compatible motor shaft, preferably with a flat. |
| Grub-screw thread | M3 | Locks against the shaft flat. |
| Drawing chamfers | C0.2 | Dimensional-drawing reference. |
These dimensions apply to the primary gear shown in the drawing. Secondary-shaft length, exact bearing dimensions and general tolerances are not specified; compare every relevant part physically when using the set in a different design.
Compatibility
The set follows the dual-gear format used in the extruders of:
- Original Prusa i3 MK2.5 and MK2.5S.
- Original Prusa i3 MK3, MK3S and MK3S+.
Compatibility is conditional because this is a style-compatible replacement rather than an original printer-manufacturer part. Before replacing the existing set, check the Ø5 mm motor shaft, available length, Ø3 mm secondary-shaft housing, support for both bearings and filament-path position.
It is not a direct replacement for an original Prusa MK2/MK2S extruder, Prusa MINI/MINI+, MK4/MK4S, XL, CORE One or Nextruder systems. Do not assume compatibility with every BMG, Clockwork, Sherpa or other dual-drive extruder: integrated and reversed versions, different shafts and different bearing arrangements all exist.
Set contents
- 1 primary gear with grub screw.
- 1 hollow secondary gear.
- 2 needle bearings.
- 1 shaft, 3 mm in diameter.
- 2 M3 square nuts.
The square nuts are only used by housings or printed parts that include the appropriate pockets. Extruder housing, motor, mounting screws, springs, idler door and hotend components are not included.
Installation and alignment
- Switch off and unplug the printer. Unload filament and allow the hotend to cool before disassembling the extruder.
- Insert both bearings into the secondary gear and install the 3 mm shaft between the two supports in the idler door or lever.
- Fit the primary gear to the 5 mm motor shaft. The grub screw must tighten against the shaft flat.
- Insert a straight piece of filament and move the primary gear until its hobbed groove is centred on the inlet and hotend outlet path.
- Check that the external teeth mesh correctly and that the secondary gear rotates freely without rubbing or tight spots.
- Increase idler pressure gradually. Insufficient pressure allows slipping; excessive pressure deforms the filament and increases friction.
- Perform a filament-loading and extrusion test before fully closing the assembly.
Extruder calibration
Changing drive gears can slightly alter the effective drive diameter. Measure actual extrusion before compensating with slicer flow. The commonly quoted 415 steps/mm for many BMG extruders must not be copied: it includes the complete extruder's 3:1 reduction and is not defined by this gear pair alone.
- Marlin: calculate
new E-steps = previous value × commanded length / actual length. Apply it withM92 E...and save withM500when EEPROM is enabled. - Klipper: calculate
new rotation_distance = previous value × actual length / commanded length, updaterotation_distancein the[extruder]section and restart Klipper. - RepRapFirmware: use the same steps/mm formula as Marlin. Test with
M92 E...and write the final value intoconfig.g.
Calibrate with the hotend at a suitable temperature and free from clogs. Repeat the measurement after adjustment and finish with a flow test. No firmware setting can correct a loose grub screw, misaligned gears, seized bearings or incorrect idler tension.
Cleaning and maintenance
- Periodically remove filament debris from the hobbed grooves.
- If lubrication is needed, apply only a very small amount of compatible grease to the external synchronising teeth and bearings.
- Keep the teeth that contact the filament completely clean and dry.
- If the motor shaft rotates while the filament remains stationary, first check that the grub screw is secured against the flat.
- A periodic under-extrusion pattern may indicate debris, wear, eccentricity or irregular gear mesh.
This set is for you if
- You need to replace a dual-drive gear set with this geometry and a 5 mm motor shaft.
- You want to repair a compatible Prusa MK2.5 or MK3 extruder after checking its dimensions.
- You can align and recalibrate the extrusion system after installation.
This set is not for you if
- You need a complete, ready-to-install extruder.
- Your motor does not use a 5 mm shaft or the secondary gear has a different support arrangement.
- You need an integrated, reversed or revision-specific version for a BMG, Clockwork, Sherpa or Nextruder.
