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Craitor: Rugged 3D Printer,

Temperature Control Chamber

Team N2 Members: Eric Shnell, Juan Gutierrez,

Duo Xu, Myriam Lopez, Elvin Lin

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Our Project Sponsor

Startup company founded by UCSD undergraduates

Focus on development of rugged, portable, intelligent 3D printers

Alpha prototype of Craitor 3D printer in partnership with the US Marine Corps and NIWIC Pacific Federal Labs

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Eric

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Overview of Project

Environment control system for 3D printing chamber temperature of 70 ±⁤ 5℃

Model temperature loss under environmental conditions of -15 to 50℃

Develop insulation methodologies

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Eric

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Project Objectives

Design an insulated chamber that can:

Support operation for a rugged 3D printer
Maintain an internal temperature under extreme environmental conditions

Market research to

select insulation, heater, and thermistor
Find potential off the shelf heater solutions

Conduct energy analysis (closed-form solution)
Model and simulate conduction heat loss to compare with energy analysis
Optimize model

Increase efficiency by decreasing the heat dissipation

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Eric

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Societal Impact

The military works as its own economy with an independent market and systems

A rugged 3D printer with temperature controlled chamber provides the military:

Accessibility
Cost-effectiveness
Time efficiency
Reliability

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Juan

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Economic and Environmental Impact

Economic Impact

Cost-efficient parts that normally cost 10 to 100 times it’s shelf equivalent can be created in minutes for cents on the dollar
Parts are already programmed so can be duplicated many times over

Environmental Impact

The temperature control chamber allows for quality parts to be created under extreme conditions with low heat dissipation on the environment
The rugged 3D printer can be taken through very harsh terrains and print as soon as stationary

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Juan

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Risk Reduction Review

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Risk Reduction Overview

Research consumer grade solutions that may assist in the development of the heater block

Develop an analysis on feasibility constraints

Develop a prototype CAD and run an initial proof of concept thermal simulation to present as our risk reduction

Finalize the scope of the project with better understanding

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Myriam

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Closed Form Solution vs Ansys/Fusion

Aluminum chamber + most expensive insulation

Case exterior temperature:

3.61℃

Aluminum chamber

heat loss: 8.35e6 Watts

Insulation

heat loss: 271 Watts

Case exterior temperature:

-12.9℃

1.28% difference

Insulation

heat loss: 274 Watts

1.1% difference

Aluminum chamber

heat loss: 8.490e6 Watts

5.2% difference

Insulation

heat loss: 257 Watts

1.7% difference

CLOSED FORM

ANSYS

FUSION 360

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Myriam

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Proof-of-Concept Closed Form Solution

Closed-form Solution

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Myriam

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Proof-of-Concept Simulation: ANSYS

Predicted Heat Loss:

78.84 W/m^2 x 1.4824 m^2

= 116.87 Watts

Highest Temperature on Case:

Max temp = 42.74 ℃

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Myriam

Figure 1: Heat flux through insulation

Figure 2: Case shell Temp gradient

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Proof-of-Concept Simulation: Fusion 360

Predicted Heat Loss:

80 W/m^2 x 1.4824 m^2

= 118.6 Watts

Highest Temperature on Case:

Max temp = 43.4 ℃

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Elvin

Figure 3: Heat flux through insulation

Figure 5: Case shell Temp gradient

Figure 4: Cross section Temp gradient

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Closed Form Solution vs Ansys/Fusion

Aluminum chamber + insulation for testing (proof of concept)

CLOSED FORM

ANSYS

FUSION 360

Max Temperature:

44.58℃

Insulation

heat loss: 124.40 Watts

Max Temperature:

43.40℃

2.6% difference

Insulation

heat loss: 118.6 Watts

4.6% difference

Max Temperature:

42.74℃

4.1% difference

Insulation

heat loss: 116.87 Watts

6.1% difference

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Elvin

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Risk Areas and Testing

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Safety

Heater

Reaches a maximum temperature of 70℃
Built-in temperature limiter
No direct contact during operation

Insulation

Maximum operating temperature above 80℃
Non-flammable
Placed on all 6 sides

Electronics and Printer

Operating temperature above 70℃

Exterior Case

Exterior safe to touch at maximum operating temperature

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Elvin

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Insulation: Self-Adhesive Mats

Option 1: Heat Barrier Sheet

Thickness = 3/16 in

Max temp. 230 ℃

R-value = not rated

Total cost: $284.40

Option 3: Mineral Wool

Thickness: 1 in

Max temp. 650 ℃

R-value = 4

Total cost: $50.64

Option 2: Polyethylene Foam

Thickness: 3/4 in

Max temp. 99 ℃

R-value = 3

Total cost: $105.84

Option 4: SmartShield

Thickness: 2/17 in

Max temp. 80 ℃

R-value = 15

Total cost: $17.99

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0.02 Btu flow rate

0.27 Btu flow rate

Elvin

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Insulation Testing

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Eric

Radiation	Percent Temperature Difference (tape)
Polyethylene Foam	41%
Rigid Mineral Wool	71%
Heat Barrier	32%
Aluminum Foam	27%

Convection	Percent Temperature Difference (tape)
Polyethylene Foam	49%
Rigid Mineral Wool	62%
Heat Barrier	38%
Aluminum Foam	37%

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Design Decisions

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Relay Considerations

Solid-state ✔

No moving parts

Faster
Longer lifespan

Durable and insensitive to vibrations

High cost
Current leakage
Heats up and may require external cooling

Mechanical

Less expensive
Capable of switching any type of load

Physical switch

Moving parts tend to fail faster

noisy
Physically large

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Duo

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Relay Options

Requirements

AC control board
Throughput of 300 watt
GPIO/5v based switch
As small as possible
Passive cooling

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Duo

Our Choice: SSRK-240D20

$59.60
2 inputs
Integrated heat sink
111.5 x 82.3 x 22.5mm

H x W x L

-30 to 80 ℃ operating temperature range

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Purchased Components

Stego PTC Fan Heater-$154
Heat Barrier purchased- $56 (One wall)
Aluminum foam insulation - $19 (all walls)
Typical 100K Thermistor- FREE

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Juan

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List of Items to be Purchased/Machined

AC Relay-$59
Heater Bracket (Shown below)

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Juan

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Objectives

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Milestones For MAE 156B

Test material performance ✔

Completed by 16th April 2021

Integrate 3D printer into prototype (Work in Progress)

Completed by 28th April 2021

Test integrated system in lab environment

Completed by 5th May 2021

Optimization of heater and insulation based on alpha testing

Completed by 19th May 2021

Testing in field (or climate control chamber) of completed environmental control

Completed by 28th May 2021

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Duo

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Project Management for MAE 156B

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Duo

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Filament Storage Bonus Project

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Duo

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Unresolved Issues

None for now!

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Duo

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Questions?

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CAD of Design and Prototype Development

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Juan

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Control Board Choices	Raspberry Pi	Azteeg X5 GT	Raspberry Pi (Temperature) & Azteeg (Motor)
Programming Languages	C/C++	G-Code	C/C++ & G-Code
Board Communication	Not Required	Not Required	Required
Motor Control	Not Supported, could be realized, must program any motor motion	Firmware Support (Bug Free!)	Firmware support
Temperature (PID) Control	Simple programming, PID controller available in Arduino library	Could be realized using G-code, Optimization required	Simple Arduino Programming
Memories	The microcontroller may not have the space required to hold all the commands	SD card supported	SD card for motor control, enough storage for temperature control
Platform	Open-source	Open-source (Easy upgrades)	Open-source
Costs	$40.30	$110.00	$150.30

Azteeg X5 GT 32bit Motion Controller

Raspberry Pi

Duo