P19462: Solar Powered 3D Printer
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Preliminary Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

During this preliminary design phase, our team identified the printer selection, power management system design and pellet extruder purchase/design as the most critical system components. The printer is the center of our design and we will base many detailed design choices on the printer specifications. The power management system is most important for delivering a working product to our customer; if the power fails, nothing about our product is useful. Finally, our solution for the pellet extruder requirement involved us purchasing a kit from a foreign vendor. We knew that if this was possible, it would take a long time to ship, and we wanted to start that process as soon as possible. If we found we were unable to buy the pellet extruder, we needed to know as soon as possible so that we could start prototyping and building our own, a process that would take a lot of time.
Design Focus

Design Focus

We set objectives for which are outlined in the image below. The objectives in green are things that we accomplished and the ones in black are things in progress.

Design Objectives

Design Objectives

The 3D printer was ordered along with a power meter so that we can determine the printer's energy demands. This will allow us to design a power system that is a good fit, and will cut costs that would accrue come from over-sizing batteries and solar panels.

Due to some challenges we faced with communicating with our overseas vendor, our team decided to go ahead and start doing some preliminary prototype work on the pellet extruder. We are still very optimistic that we will be able to acquire the kit, however, prototyping will also help to deepen our understanding of how the extruder works.

Feasibility: Prototyping, Analysis, Simulation

We benchmarked all of the printers against each other. This benchmarking didn’t take into account weighting, so we took the three best performers and considered them. They were the CR-10, CR-10S and the Pursa i3. From here the we looked at the most important requirements first. The cost of the Pursa i3 didn’t seem feasible in our budget. That left the CR-10 and the CR-10S. The main difference between the two is the ability to resume a print after losing power and a cost difference of $60. We discussed the implementation cost of adding the ability to resume a print after loss of power and came to the conclusion that it would cost more than the $60 price difference to implement the feature ourselves.

Main Criteria

Printers Considered

Printer Benchmarking

Printer Benchmarking

We benchmarked all of the printers against each other. This benchmarking didn’t take into account weighting, so we took the three best performers and considered them. They were the CR-10, CR-10S and the Pursa i3. From here the we looked at the most important requirements first. The cost of the Pursa i3 didn’t seem feasible in our budget. That left the CR-10 and the CR-10S. The main difference between the two is the ability to resume a print after losing power and a cost difference of $60. We discussed the implementation cost of adding the ability to resume a print after loss of power and came to the conclusion that it would cost more than the $60 price difference to implement the feature ourselves.

Drawings, Schematics, Flow Charts, Simulations

Electrical Diagrams

Below are 2 block diagrams for the power system.
Power System Block Diagram 1

Power System Block Diagram 1

Power System Block Diagram 2

Power System Block Diagram 2

A document outlining different power system sizing scenarios can be found here.

Mechanical Drawings

Below is a snapshot of the part drawing that was made for prototyping the pellet extruder throat bore. We wanted to test a method of machining the throat so that the bore had grooves. The grooves or "flutes" will help facilitate better pellet flow through the throat. For the full drawing, click here.
Extruder Throat Prototype Drawing

Extruder Throat Prototype Drawing

This drawing was used for reference when we went to the machine shop to cut the part. First we cut a 3in. section of square aluminum bar, then the array of 6 small diameter holes were drilled. These holes we drilled before the center bore to prevent the deflection of the drill bit that occurs when you try to cut into open space. After the smaller holes were drilled, the center bore was cut with minimal deflection. The end result is pictured below.

Machined Prototype

Machined Prototype

Bill of Material (BOM), Purchase Plan

Due to a recent scope change regarding our pellet extrusion subsystem, the bill of materials is incomplete. The purchase plan outlines when each component needs to be purchased. A completed BOM will be available before the end of the final detailed design phase. Upon completion of the energy testing of the 3D printer with a power meter (which was very recently purchased), the team will be able to determine the components needed for the energy subsystem.
Purchase Plan

Purchase Plan

Test Plans

Below is the test plan for the first two subsystems. The test plan outlines what test shall be performed as well as which engineering requirement each test references.
Test plans for Functional 3D Printer & Functional Energy System

Test plans for Functional 3D Printer & Functional Energy System

For the entire test plan please click here to open the entire spreadsheet.

Risk Assessment

Risks Identified in the Preliminary Detailed Design Phase

Risks Identified in the Preliminary Detailed Design Phase

Design Review Materials

Presentation

Preliminary Detailed Design Documents

Plans for next phase

Work Breakdown Structure and Gantt Chart for Detailed Design Phase

Work Breakdown Structure and Gantt Chart for Detailed Design Phase


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