Big printed pulleys don't need to be solid: five and six spokes on a thin centre web cut plastic and print time, while the toothed rim stays full width for the belt.
Using the CheapCAD Tools connector, design a two-pulley timing belt drive: GT2 belt (2 mm pitch), about 120 mm between centres, 8 mm bores, and on each pulley a hub 18 mm across and 7 mm tall with an M3 set screw. Lighten both with spokes on a thin web 4 mm tall, a 3 mm rim under the teeth and an 18 mm spoke hub: 5 spokes on pulley 1 (40 teeth) and 6 spokes on pulley 2 (60 teeth). Pulley 2 also gets printed flanges, with the top flange printed in place. Check the design, apply any Auto-fix it suggests, then export both pulleys as STL and give me the download link.
Paste it into Claude, ChatGPT or any AI app with the CheapCAD Tools connector, and it designs this drive with you, checks it and hands you the files. How to connect your AI.
GT-2M-40T.stl — pulley 1, 40 teethGT-2M-60T-P2+flange.stl — pulley 2, 60 teethFree STLs are CC BY 4.0, printed size without print compensation. Open the design to change anything, tune the fit for your printer, or download STEP, DXF, SVG and the belt.
| Pulley 1 | Pulley 2 | |
|---|---|---|
| Pitch diameter | 25.46 mm | 38.20 mm |
| Outside diameter | 24.96 mm | 37.69 mm |
| Outside diameter, as built | 24.98 mm | 37.71 mm |
| Root diameter | 23.43 mm | 36.16 mm |
| Groove depth | 0.76 mm | 0.76 mm |
| Pitch line differential | 0.25 mm | 0.25 mm |
| Belt width | 10.00 mm | 10.00 mm |
| Face width (belt + clearance) | 13.00 mm | 13.00 mm |
| Minimum face width | 13.00 mm | 11.00 mm |
| Flange outside diameter | — | 43.71 mm |
| Flange past the OD | — | 3.00 mm |
| Minimum flange height | — | 1.10 mm |
| Flange inward of the groove | — | 3.00 mm |
| Minimum flange overlap | — | 3.00 mm≈ |
| Belt | 171 teeth · 342.00 mm | |
| Centre distance | 120.83 mm | |
| Drive ratio | 40 : 60 · 1 : 1.5 | |
Read from the generator's Dimensions panel for this design, which opens with no warnings.
The 3D-printer classic done properly: a D-flat that keys onto the motor shaft, a set screw that bites into a captured nut instead of the plastic, and a 30-tooth partner held by two heat-set inserts.
Tuned for positioning rather than power: tight tooth clearance, no backlash allowance and 0.1 mm of print compensation, so the printed teeth hold the belt without slop.
Ready for an FRC robot: the bore fits REV ½" rounded hex shaft, with SH-50 retaining-ring grooves on both faces and a splined washer under each ring so nothing walks along the shaft.
Built like a machined part: ISO 773 keyways sized to 12 mm and 20 mm shafts, M5 set screws to lock them, and flanges drawn as bent metal plates instead of printed rims.