Electric locomotive for Ikea Lillabo/Brio train (USB rechargeable)

thingiverse

There is now a newer version available on Thingiverse. This project was inspired by MilanGajic's electric locomotive design. I wanted this model to be compact enough to fit in the Lillabo tunnel while retaining a kid-friendly locomotive look, particularly with a cow plow at the front end. I still consider this work-in-progress, as you can see below. The advantages of this model are: - it functions properly - it just fits under the Lillabo tunnel - parts simply snap together and could also be held by 3mm bolts (either directly into the plastic or in heat-set inserts) However, there are still areas that need improvement: - wheel adhesion: this can only pull two to three cars and cannot even pull itself over the Lillabo bridge. Adding an elastic should likely solve this issue, but it would require slightly redesigning the wheels. - the electric circuit (which I copied from the original) is not optimal: the LED is in series with the motor. So whenever the wheels are blocked (for example because you just picked it up), the DC motor becomes a passing circuit, which shorts and kills the LED. To fix this, the LED should be in parallel with the motor, and in series with a 100/200 ohm resistance (for blue/yellow LEDs), which might need some extra space in the model. - the switch is a toggle hidden in the chimney, but this could be made even more elegant (and easier for kid's fingers) by making the whole chimney the switch — either rotary or as a latching push-button switch. I have not yet located the correct part for this on AliExpress, so if anyone identifies a good latching push-button (with ~ 7mm hole) or rotary switch, feel free to send me the link! Extra parts needed: - small toggle switch - T-shape DC motor - small lithium battery and micro-USB charging module - 12mm ring magnet and round-head 4mm bolt & nut - 2mm wide axle for the front wheel (needs to be sawed to 33mm width) - optionally, 3mm bolts and heat-set inserts.