PARAMETRIC · 3D · STEP / STL / 3MF
Internal GearINTERNAL GEAR
Enter module, teeth, outer diameter and face width to preview an internal (ring) gear live and download STEP, STL or 3MF. Ideal for planetary gearboxes.
- ProfileInvolute
- Pressure angle14.5° / 20° / 25°
- OutputSTEP · STL · 3MF · DXF
LIVE · INTERNAL GEAR
m=1 · z=60
SCALE 1:1 · mm
Drag to rotate · scroll to zoom · right-drag to pan
CALCULATED · SPEC
AUTO-COMPUTED
D
60.00mm
Pitch diameter
Da
58.00mm
Tip (inner) diameter
Df
62.50mm
Root diameter
p
3.142mm
Circular pitch
t
4.75mm
Rim thickness
z₂max
48
Max. pinion teeth
HOW-TO
How to generate a internal gear STEP / STL file
- 1Enter module and tooth count.
- 2Set the outer (rim) diameter and face width.
- 3For 3D printing, add backlash.
- 4Download STEP, STL or 3MF — or send it to Orinovate.
What is an internal gear?
An internal (ring) gear has its teeth on the inside of a rim. It turns in the same direction as its pinion with a short centre distance, giving compact high-ratio drives — the heart of planetary gearboxes.
Specs at default parameters
| Parameter | Value | Range |
|---|---|---|
| Module (m) | 1 mm | 0.3–10 |
| Teeth (z) | 60 | 20–300 |
| Outer diameter | 72 mm | 10–1000 |
| Face width (b) | 8 mm | 0.5–100 |
| Pressure angle (α) | 20° (standard) | 20° (standard) / 14.5° / 25° |
| Backlash | 0 mm | 0–0.5 |
| Pitch diameter (D) | 60.00 mm | — |
| Tip (inner) diameter (Da) | 58.00 mm | — |
| Root diameter (Df) | 62.50 mm | — |
| Circular pitch (p) | 3.142 mm | — |
| Rim thickness (t) | 4.75 mm | — |
| Max. pinion teeth (z₂max) | 48 | — |
FAQ
Centre distance to the pinion?
a = m × (z_ring − z_pinion) / 2. A m1 60-tooth ring with a 20-tooth pinion gives a = 20 mm.
How do I choose planetary tooth counts?
Ring = sun + 2 × planet, and (sun + ring) ÷ number of planets must be an integer for equal spacing.
Why can't the pinion be too large?
A small tooth-count difference causes tip interference. Keep the difference ≥ 12 at 20°.
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Related articles
- Gear module explained: choosing a module for 3D printing and DIY2026-10-06
- The complete guide to 3D-printed gears: materials, tolerances and processes2026-10-06
- How to calculate gear ratio: single-stage, compound and planetary gear ratio formulas (with torque and speed)2026-10-07
- Planetary gearbox design: tooth count rules, gear ratio calculation and 3D printing tips (with valid tooth combinations)2026-10-07
Need a physical part?
Send the model straight to Orinovate's instant quote: FDM, SLA, SLS, MJF, metal printing and CNC, made in Hsinchu, Taiwan.
About STEP / STL / 3MF / DXF
- STEP (.step / .stp, AP214) keeps exact dimensions and surfaces for editing in Fusion 360, SolidWorks or FreeCAD.
- STL and 3MF are triangle meshes that import directly into Bambu Studio, PrusaSlicer or Cura.
- DXF is the top-view 2D outline, ready for laser cutting, waterjet or CNC routing.
- All models are in millimetres at true scale.