Heavy-duty HTD 8M on splined shafts: straight-sided ISO 14 splines carry torque no set screw could, and the 36-tooth pulley is spoked around its spline hub.
Using the CheapCAD Tools connector, design a two-pulley timing belt drive: HTD 8M belt, about 250 mm between centres, with straight-sided ISO 14 splined bores. Pulley 1: 24 teeth, a 6 × 23 × 26 spline (6 mm spline width), a hub 40 mm across and 10 mm tall. Pulley 2: 36 teeth, a 6 × 28 × 32 spline (7 mm spline width), a hub 48 mm across and 10 mm tall, 6 spokes around a 48 mm spoke hub with a 4.1 mm rim under the teeth, and flanges drawn as metal plates reaching 4.2 mm past the teeth. 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.
HTD-8M-24T.stl — pulley 1, 24 teethHTD-8M-36T-P2+flange.stl — pulley 2, 36 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 | 61.12 mm | 91.67 mm |
| Outside diameter | 59.74 mm | 90.30 mm |
| Root diameter | 52.98 mm | 83.54 mm |
| Groove depth | 3.38 mm | 3.38 mm |
| Pitch line differential | 0.69 mm | 0.69 mm |
| Spline minor (the bore) | 23.01 mm | 28.01 mm |
| Spline major (its reach) | 26.04 mm | 32.05 mm |
| Sample shaft minor | 22.97 mm | 27.97 mm |
| Sample shaft major | 25.64 mm | 31.61 mm |
| Retaining ring | DIN 471 26 × 1.2, top face (McMaster 98541A128) | DIN 471 32 × 1.5, top face |
| Ring counterbore diameter | 35.50 mm | 43.00 mm |
| Ring counterbore depth | 1.30 mm | 1.60 mm |
| Belt width | 10.00 mm | 10.00 mm |
| Face width (belt + clearance) | 20.00 mm | 20.00 mm |
| Minimum face width | 20.00 mm | 12.00 mm |
| Flange outside diameter | — | 98.70 mm |
| Flange past the OD | — | 4.20 mm |
| Minimum flange height | — | 4.07 mm |
| Flange inward of the groove | — | 4.10 mm |
| Minimum flange overlap | — | 4.07 mm≈ |
| Belt | 93 teeth · 744.00 mm | |
| Centre distance | 251.54 mm | |
| Drive ratio | 24 : 36 · 1 : 1.5 | |
Read from the generator's Dimensions panel for this design, which opens with no warnings.
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.
Splined like a gearbox shaft: ISO 4156 involute splines in module 1, with a flat root at 30° on the small pulley and a fillet root at 37.5° on the large one.
Industrial scale: an HTD 14M drive for a 40 mm belt, keyed 35 mm and 50 mm bores, a spoked 36-tooth pulley over 160 mm across, and metal-plate flanges.