Spur Gear (module 2, 12 teeth)
A 20° involute spur gear: module 2, 12 teeth, 24.0mm pitch diameter, 28.0mm over the tips, 8mm face, 5mm bore. Cut to the ISO 53 basic rack proportions — 2mm addendum, 2.50mm dedendum, 4.50mm whole depth, 3.14mm of tooth on the pitch circle — so it meshes with every other module-2 gear here and with the module-2 rack. Centre distance to another of these is half the sum of the pitch diameters. The flanks are true involutes, struck from the base circle at 22.55mm, and the roots are filleted at 0.38×module so they are not a crack waiting to start. At 12 teeth this is below the 17-tooth limit where a rack-cut 20° gear starts undercutting its own roots; built from the involute directly it does not undercut, so the root is a little fuller than a hobbed pinion's — it will mesh the same, because that is what the involute is for. A gear is close to the perfect FDM part: constant cross-section, every face vertical, no support. PETG or nylon if it is driving anything; PLA is stiff and accurate but it creeps under a steady load and it is brittle at the tooth root.
from £1.20example, in PLA
Example pricing
A guide only — not a fixed quote. Final price depends on material, quantity, print orientation and printability.
| Material | 1 unit | 5 units | 10 units | 25 units |
|---|---|---|---|---|
| PLA | £1.20 | £5.02£1.00/unit | £9.08£0.91/unit | £20.32£0.81/unit |
| PETG | £1.26 | £5.30£1.06/unit | £9.59£0.96/unit | £21.46£0.86/unit |
| ABS / ASA | £1.42 | £5.94£1.19/unit | £10.75£1.08/unit | £24.06£0.96/unit |
Per-unit prices fall with quantity. Larger batches are cheaper still — ask for a bulk quote.