20 : 30 · 1 : 1.5
XL 20T & 30T, ¼" & ⅜" Bores, Inch Set Screws
Imperial down to the hardware: an XL belt, ¼" and ⅜" shafts, and #8-32 and #10-24 set screws in captured nuts.
Sample · Timing Pulley Generator
Miniature MXL timing pulleys with M2 set screws
Small and fine-pitched: 0.08" MXL teeth on 3 mm and 4 mm shafts, held by M2 set screws in hex-shaped tapped holes.
What's in this design
The drive
- MXL (0.080″ pitch) belt, 10 mm wide, 75 teeth (152.4 mm long)
- Centre distance 50.7 mm; ratio 20 : 30 (1 : 1.5)
- Set-screw holes are hex-shaped for the screw to tap, 82% of its diameter across flats
Pulley 1
- 20 teeth
- 3 mm round bore
- Hub Ø10 × 6 mm, two M2 set screws tapped into the plastic
- Printed flanges, 1.5 mm thick, reaching 3 mm past the teeth; both print in place
Pulley 2
- 30 teeth
- 4 mm round bore
- Hub Ø12 × 6 mm, two M2 set screws tapped into the plastic
In the free STL zip
Imperial-MXL-20T+flange.stl— pulley 1, 20 teethImperial-MXL-30T-P2.stl— pulley 2, 30 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 | 12.94 mm | 19.40 mm |
| Outside diameter | 12.43 mm | 18.90 mm |
| Root diameter | 11.05 mm | 17.52 mm |
| Groove depth | 0.69 mm | 0.69 mm |
| Pitch line differential | 0.25 mm | 0.25 mm |
| Belt width | 10.00 mm | 10.00 mm |
| Face width (belt + clearance) | 12.50 mm | 12.50 mm |
| Minimum face width | 10.70 mm | 12.50 mm |
| Flange outside diameter | 18.43 mm | — |
| Flange past the OD | 3.00 mm | — |
| Minimum flange height | 0.50 mm | — |
| Belt | 75 teeth · 152.40 mm | |
| Centre distance | 50.70 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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