30 : 45 · 1 : 1.5
STD S3M 30T & 45T, Custom Tooth Fit
When the presets aren't quite right for your printer: tooth clearance and backlash dialled in by hand, on the round-toothed STD S-series profile.
Sample · Timing Pulley Generator
RPP 5M pulleys with an open three-spoke web
RPP's parabolic teeth around an open three-spoke web, with generous fillets at both ends of every spoke.
Build it with your AI
Using the CheapCAD Tools connector, design a two-pulley timing belt drive: RPP 5M belt, about 150 mm between centres, an M4 set screw in each hub. Pulley 1: 20 teeth, 8 mm bore, a hub 20 mm across and 8 mm tall. Pulley 2: 30 teeth, 10 mm bore, a hub 22 mm across and 8 mm tall, 3 spokes 6 mm wide around a 22 mm spoke hub with a 3 mm rim under the teeth, a 3 mm fillet where each spoke meets the rim and 4 mm at the hub, and printed flanges with the top flange printed in place on breakaway print supports. 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.
What's in this design
The drive
- RPP 5M belt, 10 mm wide, 86 teeth (430 mm long)
- Centre distance 152.29 mm; ratio 20 : 30 (1 : 1.5)
Pulley 1
- 20 teeth
- 8 mm round bore
- Hub Ø20 × 8 mm, two M4 set screws tapped into the plastic
Pulley 2
- 30 teeth
- 10 mm round bore
- Hub Ø22 × 8 mm, two M4 set screws tapped into the plastic
- 3 spokes, 6 mm wide, under a 3 mm deep rim, with 3 mm and 4 mm fillets
- Printed flanges, 1.5 mm thick, reaching 3 mm past the teeth; both print in place, the top one on breakaway supports for a 0.4 mm nozzle
In the free STL zip
RPP-5M-20T.stl— pulley 1, 20 teethRPP-5M-30T-P2+flange.stl— pulley 2, 30 teeth, without supportsRPP5M-30T-Assembly.stl— pulley 2 with both flanges and breakaway supports: print this one
Free 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.
Dimensions — 16 figures from the generator
| Pulley 1 | Pulley 2 | |
|---|---|---|
| Pitch diameter | 31.83 mm | 47.75 mm |
| Outside diameter | 30.69 mm | 46.61 mm |
| Root diameter | 26.57 mm | 42.49 mm |
| Groove depth | 2.06 mm | 2.06 mm |
| Pitch line differential | 0.57 mm | 0.57 mm |
| Belt width | 10.00 mm | 10.00 mm |
| Face width (belt + clearance) | 16.00 mm | 16.00 mm |
| Minimum face width | 16.00 mm | 12.00 mm |
| Flange outside diameter | — | 52.61 mm |
| Flange past the OD | — | 3.00 mm |
| Minimum flange height | — | 2.72 mm |
| Flange inward of the groove | — | 3.00 mm |
| Minimum flange overlap | — | 3.00 mm≈ |
| Belt | 86 teeth · 430.00 mm | |
| Centre distance | 152.29 mm | |
| Drive ratio | 20 : 30 · 1 : 1.5 | |
Read from the generator's Dimensions panel for this design, which opens with no warnings.
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