P17551: Sandia Instrumented 3D Printer
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Subsystem Build & Test

Table of Contents

Team Vision for Subsystem Level Build & Test Phase

At this review, we will present our progress on our next set of data analysis, including plans for further testing and new test results confirming the improvements made by the enclosure.

The updated end-state document can be found here.

This demonstration will also include the following systems of our design project:

Auxiliary points of progression, with appropriate time tables, that will be discussed:

This subsystem demonstration will feature the subsystems operating separately from one another at minimum. This is meant to confirm their operation and functionality as well as open a guided dialogue on their predicted progress at the week 8 review.

The test bed/atmospheric sensor network is not yet integrated into the printer, but the mounting bracket for the sensors themselves will be demoed and replacing the components current housing, a breadboard will be discussed. The sensor network is able to write to an SD card but parts are waiting to be delivered to make the CSV file easy to read and time-stamped.

As with any design project, there will be some unknown problems that will appear. In the case of the 3 weeks between our team’s last review and week 5, 2 separate problems were uncovered. These problems came in the form of a server hack as well as calibration issues with the printer. Thankfully, both issues were remedied and noted in the updated problem tracking document.

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Test Results Summary

Impact Testing

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Tensile Testing

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Bill Of Material

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Risk and Problem Tracking

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Security

The addition of Octoprint allowed us to access the printer remotely from the internet, increasing the printer’s up-time and accessibility. While this was a boon for the team, this also opened us up to potential security concerns that were not realized, causing the printer to be accessed late one night remotely by an unauthorized individual. As a result, we were locked out of our Octoprint interface, the individual uploaded a custom print job, and he even messaged our message group! Fortunately, the printer was off at the time so nothing actually printed.

The team quickly realized that something was happening thanks to our message group being alerted about the unauthorized print. After which the team quickly addressed the issue by first going to the printer and making sure it wasn’t actually printing anything. Afterwards the Octoprint system was quickly disconnected from the printer to avoid further harm until the issues could be proper addressed in the morning.

The team met in the morning to discuss what happened and ways to minimalism the issues moving forward. After investigating potential causes for the security concern, we discovered we did not change the default login information for our Raspberry Pi, which was where our Octoprint server was located, and thus, where our Printer could be accessed from. We concluded that the Raspberry Pi was hacked and through that our Octoprint was also accessed. The individual then used our Octoprint system to send a message to our message group, which thankfully meant that they did not have access to our message group, protecting any important information we had posted there. We responded to these problems by first changing the default login information on our Raspberry Pi to something significantly more secure. Then we looked at the specific services that our Raspberry Pi required and removed the ones we did not need. Other security measures were taken into consideration; however we decided to not implement them as they would either injury our workflow or would be overkill for what our project needed to achieve.

We do have plans that will further improve our security concerns. Due to recent mount installations and calibration concerns, we do plan to move away from Octoprint or at least removing it from the internet. This decision was made due to the recent calibration issues we’ve had with print failures that results from using the extruder to remove the last print. Additionally, this way of removing the part isn’t feasible with the new thermal camera mount. With Octoprint removed from the internet, so is our printer, removing the security concern entirely.

Subsystem Development and Demos

Sensor Array

Revised Heat Bed Test Plan

Revised Heat Bed Test Plan

All test plans can be found here.

Sensor Readings

Sensor Readings

Cameras

Current view from the HD camera.

Current view from the HD camera.

Thermal image saturated on extruder.

Thermal image saturated on extruder.

Thermal image of Benchy when not saturated.

Thermal image of Benchy when not saturated.

LED Array

32x32 LED Matrix with a 4mm pitch

32x32 LED Matrix with a 4mm pitch

Matrix with a color variance

Matrix with a color variance

Matrix during the test program showing all colors

Matrix during the test program showing all colors

Matrix showing the color wheel

Matrix showing the color wheel

Firmware

Currently the progress for Marlin Firmware improvements is slightly behind what is expected. At this point in time, nothing is actually implemented in the firmware but several portions have been written. Methods for internal data collection from the on-board sensors have been identified and are ready for use. Additionally, a method for CSV log writing has been developed and ready for implementation in the main firmware. Code has also been developed that will allow a file to be written to the internal SD card.

While all these parts have been developed separately, they have yet to be tested as a single unit. Additional testing is also necessary to approve that each method works entirely as expected for ‘evil’ input. Once tested, this system also needs to be properly implemented into the firmware, followed by adding support for the external sensors we plan to add to the printer.

The original plan for this review was to have these functions implemented into the firmware (except for external sensor support), but a few things have kept this from being achieved. The biggest issue has been the high complexity of the Marlin Firmware and the poor documentation (or lack of in some cases) of the code in general. These issues have been the main reasons why there has been a lack of implementation into the Marlin Firmware. In order to offset some of the time lost, several things were written as stand-alone methods (as mentioned above) that will be ready for implementation once the proper location in the firmware is identified. Additionally, the location of implementation must be selected very careful to minimalize the risk of introducing potentially critical errors into the printer’s system.

The current plan is to have the CSV log writing and internal sensor logging fully tested and implemented into the Marlin Firmware by the next review (week 8). If this can be done within a quick and timely manner, the external sensors will also be added into this and presented at the next review, however this is a stretch goal and is more likely to happen at the following review (week 11).

Mounting Fixtures

Camera Mount

Camera Mount

Thermal Camera Mount

Thermal Camera Mount

Point Sensor Mount

Point Sensor Mount

Array Sensor Mount

Array Sensor Mount

DOE Update

As per the results of the first DOE test, and conversations with the customer, a second round of DOE testing was begun using six of the previous nine treatment levels (all three extruder temp levels and the two highest bed temp levels). In addition, this test is being performed with the use of the enclosure, mitigating variance in ambient temperature. In order to obtain more information on error variance, the number of repetitions was increased from three to five, for a total of thirty prints in this experiment.

Due to the two critical problems that occurred during Phase 2, there were significant losses of printer up-time. As a result of the time lost from the hack and calibration problems, the second round of DOE testing was not completed. At the time of this review, only 22 of the 30 test prints have been completed. Until the completion of the test, we will be unable to make assertions on error variance for each of the six treatment levels. Initial results, while not complete, appear to verify our hypotheses on the enclosure and high bed temperature. All successful prints have resulted in perfect or nearly perfect bed adhesion, and overall quality and consistency seem to have improved.

Plans for next phase

Gantt Chart

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Week 8 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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