Gear Generator - spur, helical, herringbone gears and racks

About this generator

Real involute gears for 3D printing, from a 6-tooth pinion to a 200-tooth wheel. Pick the teeth and the module and the editor works out the pitch, outer and root diameters and the centre distance to the gear it meshes with. Backlash is built in as print clearance, so a pair turns freely straight off the plate.

Before you export anything, open the technical drawing: front and side views with every diameter, the bore and the hub dimensioned, plus a data table. Looking at it is free, so you can check the gear against your shaft and housing first and only take the file once it's right.

What it's good for

A replacement for a cracked gear in a toy, a kitchen mixer or a printer: count the teeth, measure the outer diameter and the module follows. Reductions for robots, RC models and kinetic sculptures, a rack and pinion for a sliding door or a camera slider, a herringbone pair that runs quiet and doesn't push sideways. The D or keyway bore takes a motor shaft and the set screw holds it.

What you can change

• Type - spur, helical, herringbone or a straight rack
• Teeth and module - 6 to 200 teeth, module 0.5 to 6 (1 for small toys, 2 to 3 for sturdy printed gears)
• Width - face width 1 to 80 mm
• Backlash - 0 to 0.6 mm of print clearance on every tooth
• Second gear on the same axis - its own teeth, width, type and module: a reduction stage in one part
• Bore - none, round, D, double D, hex, square or keyway, with the flat depth and keyway size
• Hub - diameter and length, with an M2, M3 or M4 set screw and a nut trap
• Lightening - 3 to 12 round holes or spokes, and the rim left under the teeth
• Rack - length up to 400 mm, body under the teeth, mounting holes
• Mating gear - the teeth of the gear it runs with, for the exact centre distance
• More options - pressure angle 14.5, 20 or 25°, helix angle and hand, profile shift, addendum and dedendum, root fillet, tooth tip chamfer
• Files - STL and 3MF to print; STEP for CAD (Fusion, SolidWorks, FreeCAD) on the Seller and Studio plans

The technical drawing

Drawn from the same outline as the 3D preview. For a gear: a front view with the pitch circle, outer and root diameters, bore and hub; a side view with the width of each stage, the hub, the bore and the set screw; and a table with module, teeth, pressure and helix angle, profile shift, pitch, outer, root and base diameters, tooth thickness, backlash and centre distance. For a rack: its outline with the holes, length, pitch and heights. Anyone can open it. On the Seller and Studio plans you can also download it as an SVG in real millimetres - it prints to scale and opens in CAD.

It warns you before it fails

A bore too big for the root circle, a hub too thin for its set screw or a D flat cut too deep would break the part, so the editor says "Will not build" under that field and gives the largest size that fits. Very large pairs show how long the build will take.

Printing

Print gears flat, face down, with 3 or more walls. The rack lies on its side with the tooth profile on the plate. PLA works for light loads, PETG or nylon for anything that runs a while.