GT2 20T & 30T, 5 mm D-Flat Stepper Pulley
The 3D-printer classic done properly: a D-flat that keys onto the motor shaft, a set screw that bites into a captured nut instead of the plastic, and a 30-tooth partner held by two heat-set inserts.
Timing pulleys today — sprockets and gears next. Set the numbers, let the app check them against the standard, and download a finished part: STL to print, STEP for your CAD, DXF or SVG to cut.
A general CAD package can draw anything, which is why a pulley takes an afternoon. Each of our tools makes one kind of part, with every option that part needs and nothing else.

GT2, HTD, T5, XL and 30+ more belt profiles. Hubs, set screws, spline and hex bores, spokes and flanges, as a single pulley or a two-pulley drive.
Learn more & open it →
Roller-chain sprockets for ANSI, ISO 606 and bicycle chains — single or multi-strand, with hubs, bores and spokes, as a two-sprocket drive.
See what it will do →
Involute spur, helical and herringbone gears by module or diametral pitch — single gears, pairs, internal rings and racks, checked against DIN 3960.
See what it will do →E-Box Designer — parametric 3D-printed enclosures for electronics: draw the box, place the boards, cut the holes, print it.
Pick the belt and tooth count, then the bore, hub, set screws, spokes and flanges. The 3D view updates as you type, in mm or inches.
The Dimensions panel compares your part with the published standard and says which one. One click on Auto-fix applies the settings that clear the warnings.
STEP at true size for your CAD, STL with print compensation for your printer, DXF and SVG with true arcs for the laser or waterjet.
Ready-made drives for the most-searched belts. Click one to open it in the generator, change what you need, and download — or take the sample STLs free.
The 3D-printer classic done properly: a D-flat that keys onto the motor shaft, a set screw that bites into a captured nut instead of the plastic, and a 30-tooth partner held by two heat-set inserts.
Ready for an FRC robot: the bore fits REV ½" rounded hex shaft, with SH-50 retaining-ring grooves on both faces and a splined washer under each ring so nothing walks along the shaft.
Built like a machined part: ISO 773 keyways sized to 12 mm and 20 mm shafts, M5 set screws to lock them, and flanges drawn as bent metal plates instead of printed rims.
Big printed pulleys don't need to be solid: five and six spokes on a thin centre web cut plastic and print time, while the toothed rim stays full width for the belt.
Tooth profiles, flange heights, keyways and retaining rings come from the published standards and the belt makers' own data — and the app tells you which.

No subscription and no seat licence. Buy a pack of tokens when you need them; every new account starts with 20 free tokens.
SVG and DXF with true lines and arcs, for laser, waterjet and CAD sketches.
STL with your print compensation applied, ready for the slicer.
STEP at true nominal size, for Fusion, SolidWorks, Onshape, FreeCAD and the rest.
No account needed to design. Open the generator and start typing.