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Michael Rechtin’s 3D-printable planetary gearbox increases reduction by stacking stages: each stage is reported as a nominal 4:1, so two stages yield 16:1 and three yield 64:1. “Unlimited reduction” is a headline, not an engineering guarantee: each additional stage adds hardware and practical limits, and the cited coverage does not establish a maximum stage count or a safe load rating.
How stacking changes the gear ratio
A planetary gearbox uses gears arranged around a central sun gear, with planet gears carried within a ring gear. In this design, the stages are modular: adding another stage compounds the reduction rather than adding four to the previous ratio.
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| Number of stages | Reported nominal reduction |
|---|---|
| 1 | 4:1 |
| 2 | 16:1 |
| 3 | 64:1 |
These examples are reported by Hackster News. The ratio is useful for understanding the design, but it does not tell you the gearbox’s efficiency, output speed under load, or usable torque.
What the design is—and is not
The project is a modular gearbox intended for a brushless DC motor. Hackaday describes its context as a low-cost, 5010-size, 360 KV sensorless brushless motor. That description does not establish that every motor with those broad specifications will fit; shaft and mounting dimensions still need to match the actual design.
#1 Best Overall
- Kit features snap or screw together construction and color molded parts to eliminate needing paint or glue
- Target Gender: Boys
- The main country of manufacture: Japan
- high quality material
- size 4.2 x 7.2 x 1.5 inches
The parts are mostly printable, but the assembly also needs non-printed hardware such as bearings and screws. Hackster reports that the plastic parts are not suited to extreme forces. The design is therefore better treated as a maker project than as a proven gearbox for demanding construction equipment or other high-load work.
Limits to consider before adding stages
- More stages mean more assembly. The sources describe stages as addable or removable, but do not establish a universally workable maximum number.
- Load capacity is not rated. No safe continuous torque, efficiency curve, backlash figure, or service-life result is established in the cited coverage.
- Noise is a reported concern. Hackaday describes the design as noisy and comments on its straight-cut teeth, high pressure angle, and loose clearances. These are observations about this project, not a blanket assessment of planetary gearboxes.
- Lubrication is mentioned, not validated as a lifespan test. Hackster says white lithium grease helped lubricate the teeth and reduce wear, but reports no controlled durability study.
How to evaluate a build for your application
- Inspect the original design files. Confirm the motor shaft and mounting dimensions, bearing and fastener requirements, and the geometry needed for the stage count you plan to print.
- Check the motor and controller together. Verify that the motor is compatible with your ESC and intended operating conditions; the coverage does not provide a universal component specification.
- Match the ratio to the job. Consider the required output speed and torque, the gearbox’s size and noise, and whether printed plastic is suitable for the forces involved.
- Verify files and licensing before use. A GitHub repository points to Thingiverse item 5437152, attributes the model to Michael_Rechtin, and reports a Creative Commons Attribution license. The original Thingiverse listing’s current files and terms should be checked directly before fabrication or redistribution.
What the reported torque figure means
Hackaday reports that the designer measured approximately 9.5 Nm through the gearbox, but the same article warns that the value may not be accurate: a sensorless motor may not produce smooth force at low speeds. Treat this as a qualified, project-specific measurement—not a rated torque, independently validated specification, or basis for sizing a safety-critical mechanism. Hackaday’s coverage provides the context for that caveat.
Rank #2
- Premium Durable Material & Solid Construction : Features high-strength steel clutch paired with premium 36T solid nylon planetary gears for long-lasting use; delivers great toughness, stable performance, wear resistance, and quiet operation for daily e-bike riding.
- Perfect Replacement Kit for Motor : Complete 36T nylon gear set with bearings and 88mm right turn clutch, ideal direct replacement Compatible With Bafang metal solid gears; solves issues like gear slipping, abnormal noise and motor failure efficiently.
- Wide Compatibility for 500W-750W E-Bike Motors : Compatible With 500W / 750W mid drive motor & hub motor, works perfectly as professional transmission spare parts for electric bicycle, e-bike conversion kits and planetary gearbox maintenance.
- Precision Dimension & Standard SpecsNylon gear size: 47.5mm outer diameter, 8mm inner diameter, 13.5mm thickness; 88mm clutch with 15mm inner diameter (GEAR CLUTCH - RIGHT/GEARCLUTCH-LEFT); strict size matching ensures easy installation and seamless assembly.
- Reliable Performance for E-Bike Repair & UpgradeThis 36 teeth nylon planetary gear clutch kit offers stable structure, high mechanical strength and long service life; must-have e-bike replacement parts Compatible With Bafang gear, hub motor and electric bike gear maintenance.
When this gearbox is a reasonable option
The design’s clear appeal is modularity: a maker can alter the reduction by adding or removing stages. It may be worth exploring where printable parts and experimental prototyping suit the application. For a working mechanism, compare it with alternatives on ratio, motor fit, envelope, noise, required speed and torque, fabrication effort, and evidence for efficiency and durability. The cited articles do not provide a controlled comparison with commercial gearboxes, so they cannot establish that this design is more efficient, durable, or economical.
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Quick Recap
Best Value
- Made of high-quality steel and equipped with 36T nylon gears, the structure is stable, impact resistant, and has good transmission performance
- Mainly used as a spare part for the intermediate drive motor gearbox of electric bicycles. the motor planetary clutch gear set is suitable for installation where the motor output shaft is on the right side
- Specially designed for 500W-750W motor, compatible with Bafang motor
- The kit includes 3 36T nylon gears with bearings and an 88mm gear holder, which can be used to replace the solid metal gears of the Bafang motor
- Please confirm the model and size before purchasing
Rank #4
- Made by Tamiya
Rank #3
- Premium Durable Material & Solid Construction : Features high-strength steel clutch paired with premium 36T solid nylon planetary gears for long-lasting use; delivers great toughness, stable performance, wear resistance, and quiet operation for daily e-bike riding.
- Perfect Replacement Kit for Motor : Complete 36T nylon gear set with bearings and 88mm right turn clutch, ideal direct replacement Compatible With Bafang metal solid gears; solves issues like gear slipping, abnormal noise and motor failure efficiently.
- Wide Compatibility for 500W-750W E-Bike Motors : Compatible With 500W / 750W mid drive motor & hub motor, works perfectly as professional transmission spare parts for electric bicycle, e-bike conversion kits and planetary gearbox maintenance.
- Precision Dimension & Standard SpecsNylon gear size: 47.5mm outer diameter, 8mm inner diameter, 13.5mm thickness; 88mm clutch with 15mm inner diameter (GEAR CLUTCH - RIGHT/GEARCLUTCH-LEFT); strict size matching ensures easy installation and seamless assembly.
- Reliable Performance for E-Bike Repair & UpgradeThis 36 teeth nylon planetary gear clutch kit offers stable structure, high mechanical strength and long service life; must-have e-bike replacement parts Compatible With Bafang gear, hub motor and electric bike gear maintenance.
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