Set module, tooth count, pressure angle, face width and bore — the generator computes a proper involute tooth profile, not a cosmetic approximation, so printed pairs actually mesh. Because the result is parametric CAD, hubs, keyways and lightening holes are one agent edit away.
The real generator runs in your browser: set the parameters, then download STEP or STL. Nothing to install, no sign-up.
The first open downloads the CAD engine (about 20 MB).
Each parameter below rebuilds real geometry on every change — this is parametric CAD, not a scaled mesh.
| Parameter | Default | Range | What it does |
|---|---|---|---|
| ModuleMODULE | 2 mm | 1 – 5 | Tooth size; mating gears must share it. |
| Number of teethTEETH | 20 | 8 – 120 | Pitch diameter = module × teeth. |
| Pressure anglePRESSURE_ANGLE | 20 ° | 20 / 25 | 20° standard; 25° for stubbier, stronger teeth. |
| Face widthFACE_WIDTH | 10 mm | 3 – 40 | Gear thickness along the axis. |
| Bore styleBORE_STYLE | circular | none / circular / hex | Center hole: round shaft or hex socket. |
| Bore sizeBORE_D | 8 mm | 2 – 30 | Shaft diameter, or hex across-flats. |
Every parameter can go in the page's link, so one link opens exactly the part you want. Example (Module 1.5, 40 teeth, 6 mm bore):https://www.forgent3d.com/en/generators/spur-gear-generator?MODULE=1.5&TEETH=40&BORE_D=6
Pitch diameter = module × teeth, outside diameter = module × (teeth + 2), root diameter = module × (teeth − 2.5). Each row opens the generator on that gear.
| Module | Teeth | Pitch Ø | Outside Ø | Root Ø | |
|---|---|---|---|---|---|
| 1 | 20 | 20 | 22 | 17.5 | Open → |
| 1 | 40 | 40 | 42 | 37.5 | Open → |
| 1.5 | 20 | 30 | 33 | 26.25 | Open → |
| 1.5 | 40 | 60 | 63 | 56.25 | Open → |
| 2 | 15 | 30 | 34 | 25 | Open → |
| 2 | 30 | 60 | 64 | 55 | Open → |
| 2.5 | 20 | 50 | 55 | 43.75 | Open → |
| 3 | 20 | 60 | 66 | 52.5 | Open → |
Two gears mesh at center distance = module × (teeth₁ + teeth₂) / 2: module 2 with 15 and 30 teeth gives 45 mm.
STEP AP214 in millimetres, exact B-rep — it opens directly in SolidWorks, Fusion, FreeCAD, Onshape or Inventor, and goes straight into a CNC quote form. STL for the slicer is one click too.
| This generator | Typical online STL generator | Vendor CAD library | |
|---|---|---|---|
| Any size within the range | Yes | Yes | Catalog sizes only |
| STEP with exact surfaces | Yes | Usually an STL mesh only | Yes |
| Changes the sliders don't cover | “AI edit” on the page | No | No |
| Account needed to download | No | Usually no | Often |
Every parameter is a link parameter; the link below opens the example part. ChatGPT, Claude or any assistant can write one like it from the parameter list (names, units, ranges) at: parameter list (JSON)
Example: https://www.forgent3d.com/en/generators/spur-gear-generator?MODULE=1.5&TEETH=40&BORE_D=6
Press “AI edit” in the generator and say what to change — a keyway, holes, a different shape. The AI edits the part's model.py and it rebuilds in your browser, with undo. A few edits a day are free without signing in; to keep the result or go further, copy it into your models and continue with the AI agent.
Edit with AI →For bigger changes, several rounds, or a part you want to keep: copy it into your models (free account). The Forgent3D AI agent reads the model.py, edits it, rebuilds it and checks the result itself.
Copy and continue with the AI agent →With a 0.4 mm nozzle, stay at module 1 or above; module 1.5–2 is the sweet spot for strong, quiet printed gears. Below module 1 the tooth flanks lose their involute shape to the nozzle radius.
Generate both with the same module and pressure angle, any tooth counts you like. Center distance = module × (teeth₁ + teeth₂) / 2. Add 0.1–0.2 mm to that distance for printed backlash.
PETG for general use, nylon for high wear. Print flat, 100% infill or at least 5 perimeters so the teeth are solid, 0.15 mm layers keep flanks smooth.
Put the numbers in the link: https://www.forgent3d.com/en/generators/spur-gear-generator?MODULE=2&TEETH=30 opens the generator on exactly that gear. Check it in 3D, then download STEP (or STL). It is free, needs no account, and the file opens directly in SolidWorks, Fusion, FreeCAD or Inventor.
Not with a slider — with a sentence. Press “AI edit” in the generator and say “add a 3 mm keyway, 1.4 mm deep”: the AI edits the gear’s own model.py (the keyway’s width and depth can become new parameters), the part rebuilds in your browser and exports as usual. A few edits a day are free without signing in.
Yes. Models you generate and the STL / STEP files you export are yours: print them, sell the prints, or use them in a product. No attribution to Forgent3D is required.
Already have your own .scad file? Convert OpenSCAD to STEP → · Preview it in the browser →
