Our final product is a triangular shaped dynamo with a handle in the one of the ends. The light comes out in the other end, when the handle is turned. All the mechanics and the motor, is placed inside of the shell. The shell consists of a top, which can be opened if there’s a need for getting inside of the house and do some changing of the components.
The first thing we did, was to pick the shape of the gears, and then we designed the rest of the dynamo from the shape of those gears.
We chose to make our house as simple as possible. Therefore, the house has a shape that fits the gears perfectly. The handle is placed in the one end of the house and is linked directly to the gears inside. The only thing we took into account was that the length and the width of the house had to be big enough to contain not only the gears, but also the motor, and the LED-board with the light, a condensator and a rectifier. Unfortunately the rectifier wasn’t dimensioned properly and therefore not usable.
We chose to give the house a length of 130 mm and the width of 65 mm. This is also a size, that fits different kinds of hands, big or small.
As earlier described, the shape of the house is also chosen from an ergonomic point of view, where we rated the triangle to be a suitable shape, when the edges are round.
We tried to minimize the print time as much as possible by making the house and the components very simple and robust by letting the surface of the parts be relatively thick. The overall print time for the our house and the small extra components was approximately 27 hours in total.
Strength and durability
It’s very important that the shell and the components have a robustness, that can hold the grip from a hand and the movement from the handle. Therefore we chose to let the shell have a thickness of 3 mm, in order for the shell not to break.
Troubleshooting linked to the printing
We quickly discovered how to improve different aspects of the printing session to avoid the print to fail:
– If the print doesn’t stick to the tape, try to sharpen it a bit more.
– Always keep an eye on the printing session at least the first 10 minutes – the plate might need some adjustments.
– Make sure that excess material from the nozzle is removed from the plate, and also from the nozzle itself.
What have we learned?
One big thing we learned is to be better to structure our time and the workproces. It was a little difficult for us to get on with the project because of queue in the FabLab.
We also learned, that the printing time for the various prints are way higher than expected, and we should therefore have been faster with the printing-session.
If we had even more time for the project, then we would do the following:
– Optimize even more on the house, so that it would fit all the components perfectly without any waste.
– Make the handle a bit bigger to make more room for the fingers when turning the handle.
– Better holding of the motor inside of the shell.
– It could be interesting to give the dynamo even more functions. The possibility of using the electronics to charge a smartphone or other USB device would not take much to realize. Implementing a 7805 or another similar component would allow charging of devices. Further testing of the dimensions of the capacitor would allow a better utilizaion of the energy available.