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BENJAMIN R. LEHRER
  • Engineering Projects
  • Skills
  • Extracurriculars
  • Course History
  • Resume
  • Contact
  • SPOT Technology
BAJA TRANSFER CASE + INBOARD BRAKING 2021
Shifter & Torque Limiter 2021
MARVIN 2018
Operation 2019
RFiClimb 2017
WOODEN SAILBOAT - IN PROGRESS
Pneumatic Road Tube 2020
Carbon fiber steering wheel 2020
Freshman Fall Design Project 2020
Wooden Car 2020
Electronic Saxophone 2016

Baja Transfer Case + Inboard Braking 2021

Johns Hopkins University - Baja SAE Team
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Objective: Design and manufacture a transfer case for a Baja SAE off-road racing vehicle featuring 4WD output and the team's first attempt at inboard braking.
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Knowledge and Skills Used:
  • AGMA Spur + Bevel Gear Design
  • Bearing Selection
  • Shaft Stress Analysis + Hand Calculations
  • SolidWorks CAD
  • Gasket Sealing Calculations + Design
  • Ansys Stress + Deflection FEA
  • CNC + Manual Mill & Lathe Machining
  • Braking System Design
  • Alloy Steel Heat Treatment
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Result: While it follows the same overall concept of the classic Baja gearbox, my transfer case stands out by implementing inboard braking and using both custom spur and spiral bevel gears. In this iteration, the ratio was changed from 7.1:1 to 7.5:1 to provide more torque to the ground and improve the vehicles hill climb performance. This decision was made while considering the top speed decrease, but determined to be the most effective course of action.

Additionally, the oil sealing solution was redesigned to include designated fill and drain holes and a cork gasket is used to seal together the clamshell sides of the case.  New in my design, as well, is alignment pins to ensure that the gears perform as designed with the maximum lifetime achievable.

Using a combination of hand calculations for stress, deflection, and fatigue, FEAs, KISSsoft gear analysis, and rethought gear-stage ratios, my transfer case as a whole is over 6 lbs lighter than the previous iteration, even with the addition of inboard braking.

My transfer case design will begin manufacturing shortly and will be used to power the 2021-2022 Blue Jay Racing car at competitions throughout the country.
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Shifter + Torque Limiter 2021

Johns Hopkins University - Baja SAE Team
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Objective: Design, analyze, and manufacture a mechanism to select between 2WD/4WD on a Baja SAE car while limiting the maximum load experienced by the drivetrain.
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Knowledge and Skills Used:
  • Shaft Stress Analysis + Hand Calculations
  • Torque Transfer Mechanisms
  • SolidWorks CAD
  • Ansys Stress + Deflection FEA
  • CNC + Manual Mill & Lathe Machining
  • Waterjet Metal Working
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Result: The previous shifter mechanism suffered from frequent reliability issues and was difficult to maintain. My version removes cantilevered shafts and utilizes a modified shifter mechanism to avoid binding in the muddy conditions found at competition.

By installing a torque limiter, using hand calculations considering maximum stresses and fatigue, and implementing FEA based optimization, I was able to lighten the dogs by over a pound.

​My design has been frozen and the manufacturing process has begun. I am excited to put my design to use on the upcoming Baja car.
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MARVIN 2018

World Maker Faire 2018
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Objective:
 Construct a wooden, robotic, 15-foot-tall, artificial intelligence driven Connect 4 game for play at the New York City World Maker Faire.
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Knowledge and Skills Used:
  • Large Scale Wood Manufacturing
  • Robotic Systems + Sensing
  • C++ Machine Learning + Algorithms
  • Arduino Microcontrollers + Code
  • Perl Based Apache Server
  • Processing Computer Graphics
  • Human-machine Interface + Control
  • Circuitry
  • Ubuntu Linux
  • Modular + Transportable Construction Design

​Result: MARVIN became the top hit at the World Maker Faire in NYC in 2018. It was featured in over a dozen separate publications about the faire and won Editors' Choice and Best in Class awards. It also hold the unofficial world record for the largest Connect-4 board.

​Reflection: For about a year, my friend Jonathan and I spent our weekends in the garage building MARVIN's components, and at the beginning of the summer we constructed him for the first time. Using a 4 foot pole, a human player places an 11 inch diameter colored game disk at the top of the column of their choosing. The disk placement is recorded by optical sensors that transmit its location to an Arduino.

​On September 22 and 23 MARVIN was displayed at the New York Hall of Science as part of the "Greatest Show (and Tell) on Earth". During setup, we encountered some fundamental issues related to our use of infrared sensors in the outdoors (they don't work). However, no problem is too large when you have access to the brainstorming power of hundreds of makers with great ideas. Together, we came up with a few creative hacks (thanks Mike from Hackaday) that fixed our problem. Once Marvin was up and running, he started winning: finishing the weekend with a winning percentage of 78% (better than any Major League Baseball season record in history). Kids and adults alike flocked from around the fair to come play him and although usually defeated, they walked away happy. Marvin became a huge crowd pleaser and received four Editors' Choice awards. 

Read More About This Project Here
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Selected Media Links:
  • Hackaday - Article
  • Hackaday - Interview
  • Popular Science - Article
  • ZDNet - Article
  • ​Make - Newsletter
  • Make - Interview
  • Makezine - Article
  • Makezine - Promotional Teaser
  • Makezine - Faire Coverage
  • Maker Faire - Facebook Promotional
  • Maker Faire - Twitter Promotional
  • IEEE - Twitter Coverage
  • IEEE - Twitter Coverage
  • EE Journal - Live Coverage
  • I Like To Make Stuff - Article Mention
  • Today In Space - Video Mention

Operation 2019

Philadelphia Maker Faire 2019
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​Objective:
​Create a supersized version of the Hasbro game "Operation," modernized with an electronic 3 axis CNC-style arm to give it a remote surgery twist.
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Knowledge and Skills Used:
  • Wood Manufacturing
  • Homemade 3-Dimensional Robotic Motion
  • Arduino Microcontrollers + Code
  • Human-machine Interface + Control
  • Circuitry

Result: The operation game was a big hit at the Philadelphia Maker Faire and was recruited to numerous other exhibitions. We were featured in many tech-oriented publications and used our platform to promote large scale at home engineering and design projects.

Read More About This Project Here
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Selected Media Links:​​
  • Hackaday - Article
  • Hackster.io - Blog Post
  • ​Arduino.cc - Article
  • Geeky Gadgets - Article​
  • Maker Faire - Pre-Faire Press
  • ​Microsiervos - Artículo en Español​​​

RFiClimb 2017

My partner, Jonathan Roach, and I are pleased to announce that we have licensed our technology to Climbalytics. A consumer version is now available!
World Maker Faire 2017​

​Objective:
Create the world's first RFID based rock climbing tracking system for production and implementation in rock gyms.
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Knowledge and Skills Used:
  • Intellectual Property Protection
  • Wood Manufacturing​
  • RFID Sensing
  • Arduino Microcontrollers + Code
  • Human-machine Interface + Control
  • Wearable Electronics
  • Circuitry
  • Modular + Transportable Construction Design

Result: At the 2017 World Maker Faire, RFiClimb received a "Best in Class" award and three Editors' Choice awards. Additionally, a further developed version of the product is now available for purchase commercially.

Read More About This Project Here
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Selected Media Links:​
  • Suburban Life - Article
  • Main Line Media News - Article
  • Friends' Central - Article​

Wooden Sailboat
​In Progress

Objective: Design and build a 12 foot wooden sailing dinghy to race on the Chesapeake Bay.
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Knowledge and Skills Used:
  • ​Wood Manufacturing
  • Hydrodynamics
  • Fiberglass Layup
  • SolidWorks CAD
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Result: From this project, I learned a significant amount about working with composite materials to create a light yet rigid and strong structure.

The boat is still an ongoing project, with the internal structure and hull finished. It is awaiting funding to complete the fiberglass layup of the hull and a final rigging install.

Pneumatic Road Tube Sensor 2020

Johns Hopkins University - Baja SAE Team
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​Objective:
 Create a self contained and portable device to measure the time that it takes for a vehicle to travel 100 feet.
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Knowledge and Skills Used:
  • ​Wood Manufacturing
  • Arduino Microcontrollers + Code
  • Basic Pneumatic Systems
  • Circuitry

Result: This project was a success and the device is now in use for testing and data acquisition of various JHU Baja SAE vehicles.

Carbon Fiber Steering Wheel 2020

Johns Hopkins University - Baja SAE Team
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​Objective:
 Design and layup a carbon fiber steering wheel for the Johns Hopkins Baja SAE car.
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Knowledge and Skills Used:
  • ​Carbon Fiber Layup Techniques + Manufacturing
  • SolidWorks CAD Design
  • Composite Layup Techniques

Result: The steering wheel was a success and is currently in operation on a JHU Baja SAE vehicle.

Freshman Fall Design Project 2020

Johns Hopkins University
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​Objective:
Design and build a device to catch a falling egg, transport the egg horizontally and vertically by a specified distance, then release the egg.
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Knowledge and Skills Used:
  • SolidWorks CAD Software
  • Wood Manufacturing
  • Engineering Design Process

Result: Device transported an egg as desired and was presented and defended in front of the mechanical engineering design class.

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Wooden Car 2020

​Objective: Design and manufacture a gasoline engine propelled wooden car to carry two people around campus.
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Knowledge and Skills Used:
  • Google SketchUp CAD Software
  • Wood Manufacturing
  • 4-Stroke Internal Combustion Engines
  • ​Basic Automobile Control Mechanisms
  • Low Budget Design

Result: The car drove well and was used to provide rides around campus for up to three people as part of a fundraising operation.

A few years later, after working on a the JHU Baja car, it is interesting to see both what we did well and where this wooden vehicle was lacking.

All in all, I am very happy with the result of this project given the budget, resources, and tools we had at our disposal.

Read More About This Project Here

Electronic Saxophone 2016

World Maker Faire 2016​

​Objective:
Design and manufacture an electronic saxophone with proper tone production and breath sensitivity.
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Knowledge and Skills Used:
  • Fiberglass Layup Techniques + Manufacturing
  • Arduino Microcontrollers + Code
  • Human-machine Interface + Control
  • Sound Processing + Production
  • Circuitry
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Result: The Electronic Saxophone won two Editors' Choice awards and a "Best in Class" award from the 2016 World Maker Faire in New York. According to PC Magazine, it was one of "The Coolest Projects at Maker Faire 2016."

Read More About This Project Here
Selected Media Links:​
  • PC Magazine - Article

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