This contraption was designed to feed solder wire down a (brake) cable – to automatically feed it to the user as they soldered. The powered winding of the wire was provided by a servo motor (with the locking pin removed), rolling between a bearing with elastic bands glued on (for friction). The model was made out of ABS Plastis Sheet to demonstrate a quick working prototype as part of the Design Modelling workshop in London (Jan 2013).
The final intent of this project is to CAD the device – to a reasonable level of accuracy so that it might be injection moulded (as a discussion/teaching example) – however I realistically expect people to 3D Print it and make their own! Let me know if you have any suggestions.
Check out the video of it working.
You might also be interested in how the switch works – as it actually used the wire and the outer metal windings of the brake cable to complete the circuit at the handle/switch end of the cable. This does mean that a first feed/priming switch is required for the first use. I have considered adding a ‘dpdt’ switch to reverse the motor (to wind it back in) – but this has not bothered users that much, so it would be a nice to have, but perhaps not essential.