Alex Denniston Mechanical Engineering Portfolio April 2009
Companies and clients are demanding more from their development teams, and therefore it is becoming increasingly important for engineers to have the ability to solve a wide variety of problems. I believe a great engineer possesses not only the strong theoretical and analytical skills gained through formal training, but also a vast array of talents that can be used to inspire innovation, maximize productivity, and motivate success.
• Woodworking • Metalworking
When these three skill sets (Creative, Constructive, and Analytical) combine, they can propel both the individual and their team to success, while remaining both efficient and innovative. My varied background and skills make me a valuable member of any team. I bring fresh ideas grounded in solid engineering fundamentals making me an asset to all problem solving situations.
• Finishing
Constructive
Creative
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• Prototyping
Analytical
• Ideation
• FEA
• Fine Art
• FMEA
• Sketching
• DFMA
• Inspiration
• Analysis
take a look...
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Battery Charger
Essential Inc.
Charging station for a rechargeable battery used in a handheld device developed during co-op with Essential Inc. Load
Used as both a charging station and a storage container for the batteries when in transit. Battery must be securely held against the electrical contacts, but there must also be a means to easily release and eject it.
Charge & Lock
Developed a number of concepts for capture and release mechanisms, created CAD models and constructed a working prototype from an SLA model. Project required an ability to continually make forward progress despite its highly iterative nature as a result of constant review and interaction with the client and their development team.
Battery
1.5 in
3
Eject
3 in
CLIENT
SKETCH
CAD
PROTOTYPE
3.4 in
Fall 2008 The main area of focus was the capture and release mechanism.
Ma
Size
The ideation phase lead to a wide variety of solutions, each with their own advantages and disadvantages.
nu
fac
This phase ensured all the reasonable options were examined, and the best features were integrated into the final design. Critical characteristics were determined by the internal team as well as the client to ensure all concerns were met and each concept was evaluated appropriately.
Robustne
ss
Feel
Grip
tur
ab
ility
Cost Numb
er of P arts
This phase required an emphasis on creativity, however maintaining sensitivity to manufacturing issues, cost, etc. was necessary to ensure all the concepts were technically feasible.
Brainstorm concepts
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Battery Charger (continued)
Lock Insert battery into chamber. Spring loaded latches lock into small indentations.
Release Front button wedges latch apart, releasing the grip on the battery.
Eject Sprung ejection sled on top pushes battery out 20 mm to allow retrieval of battery.
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Essential Inc.
Fall 2008 A mechanical prototype was built using traditional SLA methods in combination with metallized SLA to better simulate the feel and performance of the eventual production parts. Prototype was brought to the client’s internal engineering team and their panel of experts to determine the effectiveness of the solution.
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Portable Test Stand
Altitude Inc.
Portable test stand allows user to precisely lower a current material identification device down onto a sample. Test stand provides a constant and repeatable force, as well as adjustment capabilities for the sample being identified. A variety of requirements made this project particularly challenging.
Material Identification Device
Sample
Device is pointed at a sample to determine it’s material composition. This device can be used to test possible hazardous substances (e.g. biological agents, explosives, etc.).
Design Challenges:
Constant force
No tools necessary
Harsh environments
No detachable parts
Simple to operate
A constant force must be applied to the material sample to ensure consistent and accurate results.
No tools should be necessary for adjustment or calibration of the test stand.
Device must operate in harsh environments (dust, particles, liquids) and must be able to survive submersion in bleach.
Device must have no detachable parts to ensure no items are left behind in the field, rendering the device useless.
Operation of the device must be simple and straightforward, and all tasks must be completed by a user wearing bulky gear and gloves.
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Fall 2007 Downward Force
Constant Force Spring
For proper operation, the device must be pressed down onto the sample.
Constant force springs are capable of applying a constant force along their entire travel range.
However, different amounts of force will alter the readings.
As it unrolls, the tension in the metal attempts to roll itself back up. This tension creates the uniform pulling force in the tangential direction.
Due to the varying size of sample (0 - 2”) a traditional compression spring would apply increasing levels of force with increased deflection. The use of a constant force spring to push the device ensures a constant 5 lbs is applied to the sample, regardless of size.
Handle always depressed to the same height regardless of sample size
2” sample height
1” sample height
0” sample height
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Portable Test Stand (continued) Through the use of two independent sliding systems, the operation is simplified as the user fully depresses the handle, regardless of the Activation sample size. This helps eliminate user error in the measurement process.
Simple quarter turn style attachment quickly locks the device to the test stand. A kinematic mount ensures the device is always locked into the exact same orientation, Locking and alignment eliminating the need for frequent calibration.
A linear slide system allows the device to translate vertically. The use of plain bearings (no moving parts) allows the test stand to operate in harsh environments without a Translation loss in functionality or shortening it’s lifespan.
X-Y table accommodate’s a flat or curved glass plate for the sample. Quick adjustments can be made with a simple push-pull lock that allows a sample Sample adjustment to be moved freely, then locked down for the measurement process.
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Altitude Inc.
Fall 2007 Once the concept was finalized with the client, a mechanical breadboard was constructed to serve as a proof of concept of the various mechanisms. Then a second model was created taking into account the desires of the industrial design team, as well as some of the functional requirements of the actual product (enclosure of components, manufacturability issues, etc.). Mechanical Breadboard
Second Iteration
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Air Hose Attachment
Essential Inc.
Method for supplying cold air to front of existing handheld medical product.
Design Challenges
Device must attach to product and must be capable of being quickly and easily moved or removed for calibration purposes. Existing product geometry could not be altered as the air hose would be an aftermarket option to a product already in production. Additionally, aspherical shape offered limited to no opportunities for registration Operation
User must be able to quickly and correctly attach and detach hose with one hand
Repeatability
Air flow must always be directed at the same spot
Shape
Limited opportunities to securely lock onto body of the product
Cold
Device must insulate the user from the intense cold
Cold air hose
Existing product
?
Brainstorm samples
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Attachment
Fall 2008 Attachment
SLA Model
FDM Model
Rear bracket utilizes existing screw recesses in product to lock position
Sliding pin locks two halves together and ensures firm clamp around product
SLA model to prove validity of attachment concept
Back of hose attaches to rear latch in a mortis and tenon style joint
Concept utilizes a three piece assembly: • Rear Latch • Rigid Tube • Front Latch
Ball detent locks tenon into rear latch
FDM model advanced previous concepts, retaining the attachment method while adding a spring loaded button to release clamp
Front support proved to be unnecessary for stability, so it was removed to simplify the final design
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Foot Bridge
Personal Project
Foot bridge designed and built for access to front patio. Allows for easy passage over occasionally flooded gully and establishes flow from the house to the patio. Includes visual elements characteristic of Asian gardens and architecture, while refraining from being overtly thematic. A simple design allowed the creation of this bridge to take place over a short period of time with limited tools and budget. Constructed from white pine, stained for weatherproofing.
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9 ft. 4 ft.
Summer 2006
Three 2 x 8s were joined together using glue and biscuit joints. After tracing the appropriate radius, a jigsaw was used to cut out the arches.
After screwing the deck onto the arches, the appropriate sized holes were cut to allow the main railing supports to protrude out.
The main railing supports were then screwed into the arches to serve as the attachment point for the main railing that would lay on top.
The top railing was bent over the main supports and finished with decorative caps. Lastly, the sub-railing supports and rail were attached.
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Floor Lamp Standing floor lamp designed to provide soft ambient light as well as functional shelving. Ultimately designed for use in an apartment setting where space is limited and multifunctional furniture is a must. Design allowed the lamp to look appropriate whether or not the shelves were utilized. Through the use of pocket screws, all fasteners are hidden from view, creating a clean and simple appearance. Constructed and wired so lamp shade could be removed for shipping or moving purposes.
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Personal Project
Winter 2007
Shelving system The lamp can provide simple illumination or act as an elegant piece of furniture for storing or displaying objects.
Pocket screws
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Bed Frame Custom bed frame to fit queen sized bed. Designed to be low cost, simply built, and easily broken down and reassembled numerous times. Disassembles into components capable of being transported in a small sedan. Allows for mattress to lay on top, without the need for a box spring. Drawer slides allow side panels to slide up and down, allowing for under-bed storage, while maintaining a clean platform bed look when the panels are down.
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Personal Project Brainstorm Sketches
Current Products
Fall 2007
Inexpensive Materials
Easily Disassembled
Portable
Storage Space
Design for Small Spaces
The frame breaks down into small, easy-to-manage pieces. This simplified the construction of the bed, as only four distinct parts had to be designed and then replicated. By breaking down into easy-to-manage linear pieces, this allows the entire queen sized frame to disassemble into parts capable of fitting into a small sedan (utilizing the pass through in the back seat). When moving residences, this quick and simple break down turned a sizeable bed frame into pieces easily stored in the leftover spaces in the moving truck. This also simplified the process of transferring the bed frame from the workshop where it was created, up the tight spiral staircase to the bedroom.
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Bed Frame (continued)
Personal Project
1 4
3 2 While the use of glue or wood screws would have simplified the initial construction, this design allows the frame to be broken down and reassembled as many times as desired, with no loss in the strength or integrity of the joints.
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Fall 2007
Cabinet drawer slides allow the side panels to glide up and out of the way to give easy access to the under bed storage area.
The support slats rest in slots, utilizing the weight of the mattress to hold them in place, eliminating the need for additional fasteners.
1
3
2
4
The use of threaded inserts (tee nuts) serves two purposes: it creates a robust way of connecting the two pieces, and prevents the need for access to the inside of the frame to tighten/loosen the bolts.
The cross supports rest on joist hangers and are attached to the legs using double ended screws (wood screw on one end and 1/420 machine screw threaded into a nut on the other side).
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Assorted Projects
Various
Equipment Wireless Audio
ike Fixed Gear B
Assisted in database development of audio equipment.
Custom built fixed gear bike.
Utilized master model techniques within CAD program.
ll Art Decorative Wa Decorative wall art made out of poplar. Use of biscuits ensured no visible fasteners. 21
2006 - 2009
odel D isplay Case M
Full scale model of a display case built from Foam-Cor. Heavy emphasis on dimensional accuracy as well as quality and appearance of model.
IDSA 2007 D erby Car
End Table
Entry into 2007 IDSA Derby Car Competition.
End table built from white pine, aluminum, and glass.
Machined brass chassis with painted SLA cover.
Designed so no fasteners were visible. 22
Thank you. Alex Denniston - alexdenniston@gmail.com 919.812.0424
practical skills Modeling Software: SolidWorks, Pro/Engineer, AutoCAD, 3D Studio Max Other Software: ANSYS, MATLAB, Adobe suite (Photoshop, Illustrator, InDesign), Microsoft Office Physical: Bridgeport, Metal Lathe, common metal and woodworking tools
work experience Essential Design - Boston, MA Design Engineering Co-op • Contributed to the design and development of a variety of consumer and industrial products • Helped design, build, and test functional and appearance prototypes and models • Generated 3D CAD for prototype and production parts and products • Participated in brainstorm sessions for concept generation and problem solving • Assisted industrial design team in ideation and image mapping Altitude Inc. - Somerville, MA Design Engineering Co-op • Assisted in all aspects of the product development cycle for various products • Addressed issues of manufacturability, user interaction and aesthetics within products • Prepared feasibility studies with emphases on component sourcing and research • Developed presentations and conducted phone conferences with clients • Conducted market and retail audits, interpreted and presented data Color Kinetics Incorporated - Boston, MA Mechanical Engineering Co-op • Performed various tasks to test and produce LED lighting fixtures • Helped design products and parts for mass production • Conducted thermal/mechanical tests, developed lab reports, and prepared presentations • Worked in machine shop to alter and design prototypes • Contacted outside vendors regarding manufacturing quotes and information
background & interests • Enhanced knowledge and abilities with most wood and metal working tools and procedures • Experience in fine woodworking, bicycle maintenance/assembly, and computer building • Assisted in installing car audio equipment, deck construction, and building rock climbing walls • Proficient in German language as well as participated in high school exchange program
education Northeastern University, Boston, MA BS Mechanical Engineering, Concentration in Art - May 2009 GPA: 3.69 Honors: Tau Beta Pi (Engineering Honor Society), University Honors Program, Dean’s Scholarship