P17551: Sandia Instrumented 3D Printer
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Integrated System Build & Test

Table of Contents

Team Vision for Integrated System Build & Test Phase

Shared Vision Document

Shared Vision Document

Upkeep and Update Document

Upkeep and Update Document

Test Results Summary

DOE

The second round of DOE experimentation was completed with a larger sample size and one fewer level for bed adhesion. The summarized results are below:

DOE2 Results

DOE2 Results

Standard Deviation of Each Metric

Standard Deviation of Each Metric

The results strongly indicate the use of the low settings for bed and extruder temperatures, which we believe to be a result of the enclosure. A few print failures increased the error in some categories, but the 20070 print (the desired print, according to our data) had the lowest overall variance in addition to higher quality scores.

Bed Adhesion LM

Bed Adhesion LM

Layer Adhesion LM

Layer Adhesion LM

Warping LM

Warping LM

Stringing LM

Stringing LM

Linear models did not prove that the two factors were statistically linked to quality change in most cases, due to the low number of replications, but did detect the impact in the most significant cases.

Inputs & Source

Sensor Network

Array Sensor Projection

Array Sensor Projection

Array Sensor Location

Array Sensor Location

Matlab Script

Matlab Script

Block Schematic

Block Schematic

PCB Schematic

PCB Schematic

LED Matrix

Program for color wheel

Program for color wheel

Color wheel on our board

Color wheel on our board

Program for different shapes

Program for different shapes

Shapes example on a 16x32 board

Shapes example on a 16x32 board

Program for text messages

Program for text messages

Outputs & Destination

Sensor Network

LED Matrix

Thermal Camera

Part Testing

Impact Testing

An impact specimen was printed solid and tested and the impact energy was close to 2N. This is much too small to be able to generate any valid conclusions due to changing print properties when the error is 1N. Therefore, going forward we are going to concentrate all of our energy on the Tensile DOE test as well as geometric accuracy testing.

Tensile Testing

Only three tensile specimens were printed since the previous review due to numerous print failures. The specimens printed are all highly warped and more tuning needs to be done to the print properties and/or the printer to create more acceptable specimens.

Geometric Accuracy Testing

Initially it was thought that the 3D scanner that we have access to had 100 micron accuracy it has become evident that it only has 1mm accuracy. This will not be accurate enough to show any inconsistencies between the benchy specimens. Going forward we are going to use what has been learned from the qualitative DOE testing to start printing the NIST parts. These parts will be measured using calipers and a CMM pending access to it. For the remainder of this project we will only be printing NIST parts and Tensile specimens to perform DOE testing. The technical drawings for the NIST specimen are shown below.
NIST Drawing Part 1

NIST Drawing Part 1

NIST Drawing Part 2

NIST Drawing Part 2

Firmware

Status

Currently the firmware development is behind schedule. The plan for this review was to have the internal sensor data accessible and printed to a csv file on the SD card. At this point, the data is accessible within the system and is formatted to write to a csv file, however writing to system’s SD card is proving to be challenging. Additionally, the data collection was setup to allow for expansion and additional data to be added before writing out to the csv file. The plan for the next phase is to be able to write the collected data to the SD card and integrate the internal and external data in the system.

Important Methods

Modified Firmware Important Methods

Modified Firmware Important Methods

Issues

The biggest issue currently is the inability for the 3D printer to perform more than two file operations at one given moment. Currently while the printer is printing anything, it must be performing file operations to read the print data as it comes in, instead of storing all of it within the program. While this is great for performance and stability, it does create the inability to log csv data as we acquire it from the internal sensors. Since the firmware is not written in an object-oriented manner with little documentation available, this problem is more difficult than just adding another ‘sdfile’ object. Additional methods and modifications are being written into how the firmware handles sd cards in order to add this new functionality into the system.

Another issue that has been showing up is the ‘Watchdog’ for the firmware will occasionally cause the firmware to enter a kill state. Normally, this is the intended function of the Watchdog as its job is to guard against system hang-ups and cleanly terminate printer functionality if the system does hang-up. This is achieved by having the watchdog expect a ‘heartbeat’ message within a timeout period of the last heartbeat. Currently, the modified firmware will occasionally trigger the watchdog by not sending a heartbeat within the timeout window. The cause of this is currently being investigated using timers to time critical execution components of the firmware.

Other issues have popped up, but they have been minor and easily solvable in nature. Initially, the lack of a ‘main’ entry point into the code was an issue, but this was resolved by reading both the documentation for the Arduino and the Marlin firmware and discovering that they use a ‘setup & loop’ paradigm where the setup is the entry point, and loop is constantly looped. Other issues have been of a syntactical nature, such as having issues with how the marlin system works with character pointers for string construction, how the system accesses its internal data, how the system manages SD cards, how the system manages its memory and data members, and function calls.

Bill of Materials

Bill of Materials

Bill of Materials

Risk and Problem Tracking

Risk Management Document

Risk Management Document

Problem Tracking Document

Problem Tracking Document

Plans for next phase

Gantt Chart

Gantt Chart

Gantt Chart

Week 11 Shared Vision

The shared vision for the Week 8 review will include updates bulding upon the topics discussed today.

Three Week Plans


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