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
L-pitch timing pulleys with keyed ½" and ¾" 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.
What's in this design
The drive
- L (⅜″ pitch) belt, 10 mm wide, 68 teeth (647.7 mm long)
- Centre distance 204.22 mm; ratio 20 : 30 (1 : 1.5)
Pulley 1
- 20 teeth
- ½″ (12.7 mm) bore with a ⅛″ (3.175 mm) keyway, 1.6 mm deep
- Hub Ø30 × 12 mm, one #10-24 set screw tapped into the plastic
Pulley 2
- 30 teeth
- ¾″ (19.05 mm) bore with a 3/16″ (4.7625 mm) keyway, 2.4 mm deep
- Hub Ø38 × 12.7 mm, one 1/4-20 set screw tapped into the plastic
- Metal-plate flanges, 1 mm sheet, flared at 15°
In the free STL zip
Imperial-L-20T.stl— pulley 1, 20 teethImperial-L-30T-P2+flange.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 | 60.64 mm | 90.96 mm |
| Outside diameter | 59.88 mm | 90.20 mm |
| Root diameter | 54.54 mm | 84.86 mm |
| Groove depth | 2.67 mm | 2.67 mm |
| Pitch line differential | 0.38 mm | 0.38 mm |
| Belt width | 10.00 mm | 10.00 mm |
| Face width (belt + clearance) | 14.30 mm | 14.30 mm |
| Minimum face width | 14.30 mm | 11.30 mm |
| Flange outside diameter | — | 96.20 mm |
| Flange past the OD | — | 3.00 mm |
| Minimum flange height | — | 1.50 mm |
| Belt | 68 teeth · 647.70 mm | |
| Centre distance | 204.22 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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