Dynamo Project: Optimization

Skærmbillede 2015-04-10 kl. 11.06.02

Since creating the first designs, we have optimized our dynamo according to a set of criteria given in the project description. Most importantly, we have throughout our design proces kept the desired manufacturing technology (3d printing) in mind when designing the parts.

The set of criteria is as follows:

  • Size
  • Weight
  • Ergonomics
  • Print time
  • Strength and durability
  • Light and electricity

Size

Making the dynamo as small as possible was one of our main concerns during the design process. This is evident in the final design, in which almost all space within the dynamo is used, and as a result the amount of empty space is very small. We shortened the shafts as much as possible to make room for the electronics.

Side view showing the mechanical design including the gearing. The white space in the bottom left corner is for the electronic components.
Side view showing the mechanical design including the gearing. The white space in the bottom left corner is for the electronic components.

Weight

The dynamo is relatively heavy because of the ball bearings, but we want it to be stable and easy to use. Therefore we chose to use bearings. One positive side effect of the weight is that the final product feels solid and robust, and you would not expect it to fall apart when used or carried around.

Ergonomics

It is important for us to make the dynamo easy to use and we talked about making finger marks, but we didn’t select to do this because it would make the dynamo bigger. Size was more important to us, and the final oval shape of the dynamo actually isn’t uncomfortable to hold due to the small size.

Print time

It was very important for all of us that almost all (but a few) parts could be printed without the use of support material. One way to do this was to design some of the parts with very steep angles on some pieces

Steep angles allowed a print with no support
Steep angles allowed a print with no support

We printed most of the parts with a layer thickness of 0.14 mm and medium to solid infill. This gave us a total print time of 11 hours and 20 minutes, and a filament use of 35.99 meters, equal to 86 g.

Printing the parts
Printing the parts

Strength & durability

The weakness of the dynamo can be found where the DC-generator and wheel is glued together. This area gets twisted when the dynamo is working and the torque is big here. The same applies where the shaft is glued together using acetone. Apart from that, our design is very stable due to the roller bearings, thick gears and compact design.

Light & electricity

At first we only used the motor, gearing and a LED but as we learned more (an iterative process) about the electronics we improved the dynamo incorporating a capacitor and a joule thief. Furhtermore we changed the LED from a small red LED to a bigger white LED. Read more about this here.

– ES & MN

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