Table of Contents
Team Vision for Detailed Design PhaseOur goal for this phase was to build and test our 3D printer using filament in order to test its function and power requirements.
We were able to confirm that the printer's built-in "Resume Print" function works as intended, and allows printing to resume after power failure. This function is important for meeting our customer requirement for the printer to "fail gracefully."
We also conducted power load testing and found that the printer draws much less power during heat up and printing than the rated max power requirement. This means the size of our power system can be much smaller which in turn will make the end result more compact, weight less, as well as cost less. We will be able to utilize many key electrical components that were donated to us by Mike Buffalin including a battery, MPPT controller, and inverter.
Also during this phase, we continued to work on other key subsystems of the project including the cart and enclosure design.
Prototyping, Engineering Analysis, SimulationThe energy demand chart below shows the average energy use of the 3D printer through out ten test prints. Measurements were taken on 30 second intervals.
Block Diagram for the Electronic System
List of Key Components for Electronic System
Drawings, Schematics, Flow Charts, SimulationsA rough model of the cart design was made in Solidworks. The printer and it's control box will be on the top of the cart, and will have an enclosure (not pictured) that will shield the components from wind and rain. It will also be necessary to enclose the laser while it is running for safety. The enclosure can also benefit 3D prints, especially if the material needs high temperatures to melt and adhere to the print bed and subsequent layers.
The bottom of the cart will house the electronics including the AC/DC power supply, switch, controller, battery, inverter, and fuses. Wiring will run up one of the legs of the cart into the AC outlet in the bottom of the top shelf; this is where the printer can be plugged in. A cover will be made to fit over the bottom shelf so the electronics can be sealed against water and protected. The benefits of keeping the electrical components on the bottom self rather than attaching them to the underside of the top shelf is that they will be much easier to access and it also prevents the cart from becoming top heavy which mitigates some risk of tipping.
Finally, the solar panels we have selected for this project are small enough in size that they can be stacked in the middle of the cart. They need to have some sort of spacer in order to protect against rubbing/scratching which would damage the modules. The panels would be tied down so they are secured. By stacking them in the middle of the cart rather than racking them on the sides, the overall footprint of the cart is reduced and the panels will be better protected.
To view the Solidworks CAD models, click here.
The live purchase records document is available here. The items purchased during this phase were PLA plastic pellets for printing, a converter cable for the inverter, painter's tape for the print bed, a solar panel for testing, extension cables for the printer connections, and an AC to DC power supply. We are on track with our purchase plan.
Test PlansNo changes have been made for the test plan since the preliminary design review. Please review the "plans for next phase" to see the expected test dates for each subsystem within the printer. The detailed test plan can be found here Test Plans
The following are the risks mitigated in the Detailed Design Phase
- Failure to successfully assemble printer: The printer has been successfully assembled
- Open source software utilized by the team fails: The team is utilizing the printer's software as is
The following are the risks identified in the Detailed Design Phase
- The final design might not fit in the elevators
- The system enclosure and weatherproofing measures might fail
- The cart wheels might get stuck during transportation
The fully updated risk management document can be downloaded here.