The Gtech Cordless Lawnmower comes with a plastic safety key. If the key is misplaced, the mower will safely not work. A spare key became a 3D printing project.
I measured the dimensions of the key using a digital caliper and modelled it in Autodesk’s Fusion 360. I exported the model as an STL file and sliced it with Cura 4.4.1. The slicing settings for 1.75 mm PLA included a layer height of 0.2 mm, a line width of 0.4 mm, tree support and a print temperature of 210 °C. The model comprised verticals and hortizontals, so I tilted it by 45°, to minimise the support that would be required during printing.
In respect of fidelity, the key was modelled with a diameter of 40 mm and the finished 3D print had a corresponding diameter between 40 mm and 40.5 mm (slightly elliptical – 1.25% longer on one axis – rather than circular).
The print temperature may have been too high. The tip of the key was not sharp and softened as if melted. However, the printed key works with the mower as a spare.
