20 : 30 · 1 : 1.5
RPP 5M 20T & 30T, Three-Spoke Web
RPP's parabolic teeth around an open three-spoke web, with generous fillets at both ends of every spoke.
Sample · Timing Pulley Generator
S3M (STD) pulleys with a 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.
What's in this design
The drive
- STD S3M belt, 10 mm wide, 111 teeth (333 mm long)
- Centre distance 110.02 mm; ratio 30 : 45 (1 : 1.5)
Pulley 1
- 30 teeth
- 6 mm bore with a D-flat 0.5 mm deep
- Hub Ø18 × 7 mm, one M3 set screw tapped into the plastic
- Printed flanges, 1.5 mm thick, reaching 3 mm past the teeth; both print in place
- Tooth clearance 0.08 mm (custom); backlash 0.04 mm (custom)
Pulley 2
- 45 teeth
- 8 mm round bore
- Hub Ø20 × 7 mm, two M3 set screws tapped into the plastic
- Tooth clearance 0.08 mm (custom); backlash 0.04 mm (custom)
In the free STL zip
STD-3M-30T+flange.stl— pulley 1, 30 teethSTD-3M-45T-P2.stl— pulley 2, 45 teeth
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 — 14 figures from the generator
| Pulley 1 | Pulley 2 | |
|---|---|---|
| Pitch diameter | 28.65 mm | 42.97 mm |
| Outside diameter | 28.25 mm | 42.58 mm |
| Outside diameter, as built | 28.41 mm | 42.74 mm |
| Root diameter | 26.13 mm | 40.46 mm |
| Groove depth | 1.06 mm | 1.06 mm |
| Pitch line differential | 0.20 mm | 0.20 mm |
| Belt width | 10.00 mm | 10.00 mm |
| Face width (belt + clearance) | 10.50 mm | 10.50 mm |
| Flange outside diameter | 34.41 mm | — |
| Flange past the OD | 3.00 mm | — |
| Minimum flange height | 1.26 mm≈ | — |
| Belt | 111 teeth · 333.00 mm | |
| Centre distance | 110.02 mm | |
| Drive ratio | 30 : 45 · 1 : 1.5 | |
Read from the generator's Dimensions panel for this design, which opens with no warnings.
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