20 : 30 · 1 : 1.5
L 20T & 30T, ½" & ¾" Keyed Bores
The ⅜" L pitch for heavier inch-sized machines: ½" and ¾" bores with ⅛" and 3/16" keyways, and a 1/4-20 set screw on the larger hub.
Sample · Timing Pulley Generator
XL timing pulleys with inch bores and 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.
What's in this design
The drive
- XL (0.200″ pitch) belt, 10 mm wide, 73 teeth (370.84 mm long)
- Centre distance 121.65 mm; ratio 20 : 30 (1 : 1.5)
Pulley 1
- 20 teeth
- ¼″ (6.35 mm) round bore
- Hub Ø18 × 9 mm, two #8-32 set screws in captured nuts
- Printed flanges, 1.5 mm thick, reaching 3 mm past the teeth; the top flange prints separately
Pulley 2
- 30 teeth
- ⅜″ (9.525 mm) round bore
- Hub Ø22 × 10 mm, two #10-24 set screws in captured nuts
In the free STL zip
Imperial-XL-20T+flange.stl— pulley 1, 20 teethImperial-XL-30T-P2.stl— pulley 2, 30 teethImperialXL-20T-3DP-upper-flange.stl— pulley 1's top flange, printed on its own
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 | 32.34 mm | 48.51 mm |
| Outside diameter | 31.83 mm | 48.00 mm |
| Root diameter | 28.53 mm | 44.70 mm |
| Groove depth | 1.65 mm | 1.65 mm |
| Pitch line differential | 0.25 mm | 0.25 mm |
| Belt width | 10.00 mm | 10.00 mm |
| Face width (belt + clearance) | 12.90 mm | 12.90 mm |
| Minimum face width | 11.00 mm | 12.80 mm |
| Flange outside diameter | 37.83 mm | — |
| Flange past the OD | 3.00 mm | — |
| Minimum flange height | 1.00 mm | — |
| Belt | 73 teeth · 370.84 mm | |
| Centre distance | 121.65 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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