Engineering seniors design portable toy tractor manufacturing machine to engage kids in making process

While Wisconsin farmers are out in their tractors preparing their fields, engineering students at UW-Stout have designed a portable manufacturing cell - a semi-automated assembly machine - to produce wooden toy tractors for area children.

The cross-disciplinary Taft Wooden Toy Assembly System group is made of five mechanical engineering and manufacturing engineering seniors: Owen Coon, of Appleton; Ben Gurka, of Beloit; Kierce Hemauer, of Menomonie; Ryan Kahl, of Menomonie; Aili Klein, of Lakeville, Minnesota; and Dominick Widi, of Stillwater, Minnesota.

The two-semester-long project concluded their Engineering Technology Capstone 2 course, under the guidance of Assistant Professor Kevin Dietsche. The manufacturing cell is 40 inches wide, 38 inches long and 36 inches tall. Its height makes it accessible to elementary children, as Dietsche plans to transport the machine to area schools to demonstrate the toy manufacturing process. He can also show the cell on campus tours and at industry conferences. The machine is fully enclosed with safety features, allowing Dietsche to pause assembly and talk about the process.

Constructed to be able to fit in the back of Dietsche's minivan, the two-part portable cell can be easily assembled and disassembled by one person, and its lightweight aluminum extrusion and plexiglass frame meets OSHA's standards for a two-person lift. It can produce 20 tractors in an hour, including the main body, front and back wheels, and two dowel axles.

On May 1, the group showcased their system to engineering and technology faculty, as well as retired faculty members John Schultz and Professor Emeritus Jerome Johnson and City of Menomonie representative Megan Hines, environmental program coordinator with the Urban Forestry Board.

They presented again on May 4 to faculty, peers, industry partners, family and community members as part of the Senior Design Experience, which blends the university's polytechnic tenets of applied learning and research, business and industry collaboration, and career-focused experiences.

The wooden toys, ducks and tractors are constructed from ash tree lumber provided by the City of Menomonie's Urban Forestry Board.

An interactive toy manufacturing experience for kids

Challenges for the Taft Wooden Toy Assembly System group began on day one, as they essentially needed to redesign the previous group's manufacturing cell from scratch. The previous design had broken and was not usable for testing.

However, this also gave them the opportunity to revamp the design in their own way. Their concept ideas in CAD included updating the sheet metal frame to a stronger aluminum extrusion and plexiglass frame. This was also a durability and safety consideration. The original sheet metal frame had sharp corners and was not as solid - features the group deemed unsafe, since the machine is meant to be accessible to children.

With Dietsche as their project sponsor, the group's lead capstone instructors were Assistant Professor Nathan Spike and Senior Lecturer Glenn Bushendorf, to whom they presented their initial research and design concept for critique. The group was aided by Instrumentation Coordinator-Instructor Paul Craig and Lecturer Brandon Dick for coding and controls and Lecturer Mike Miller with sensors.

"The build phase brings a spark to see the fully functional machine. Our overall design has changed a lot. It's two inches bigger and wider than our initial concept. The cell originally had seven doors, but after talking with Paul, we changed it to have one plated door on top. This cut down on the number of safety latches that we needed," Hemauer said. "The machine also has an emergency stop button, and if the door is opened during production, the machine will stop."

The wooden tractor components are fed by Dietsche through the top door into 3D-printed gravity-fed chutes. Then, like a mini-Henry Ford assembly line, five actuators - one for the body and one for each wheel - feed the components through the machine.

At first, the group designed the machine to be automated. "But we switched to have the dowels be manually inserted through the wheels, so kids can engage in the making process," Klein said. "We also included a human-machine interface (HMI) touch screen for kids to give them an industrial feel. The screen shows images to guide kids through the steps of making the tractor."

It was Hemauer's idea of a Pez dispenser that evolved into the bolt-action idea of the manual insertion of the dowels, similar to how a ball is launched in a pinball machine. The insertion of the dowels is a press-fit operation, with no glue involved.

In their research, the group found that the pull force of a 6- to 10-year-old child is 22 pounds. They made the pull factor of the wheels 60 pounds for added safety and durability, knowing children would try to remove the wheels. They also imagined children would attempt to sit on and ride the tractor, although it is only 6 inches long and 3 inches high. With extra-strong dowels, made of oak, and chamfered wheels for structural integrity, the tractor can support up to 200 pounds.

A controls box mounted on the front of the machine houses the circuit board. They also added a plaque commemorating the professorship project, as well as ash wood brackets to cover the metal brackets on the exterior casing, giving the machine a warmer appearance.

The group enjoyed the cross-disciplinary project and understands the importance of the experience as they prepare to graduate and enter the workforce. "Working across majors helps you see other people's point of view and their strengths," Gurka said. "We're building communication skills and the confidence to ask each other questions. It's being able to admit when you don't know something and being able to fall back on each other for knowledge."

A collaboration connecting people to people

The project concludes Dietsche's three-year G.A. Taft Manufacturing Engineering Endowed Professorship, in which various groups of students designed toys with first-graders, created AI rapid prototypes of toys with kindergartners and built a two-wheel toy assembly system to produce a wooden duck, including its body, wings, wheels and dowel axle.

The collaboration between the engineering and technology department and the city's Urban Forestry Board began nearly a decade ago with the support of a Wisconsin Department of Natural Resources grant. As the city's ash trees were dying and trees were being cut down, the grant funded the cutting, acquiring, milling, and kiln-drying of the ash wood. The repurposed wood was then used in student projects, creating benches for the City of Menomonie parks.

The projects were fostered under the guidance of Johnson and Nancy Schofield, a former UW-Stout professor and member of the Urban Forestry Board, who has since passed.

"Students wanted to see something that they built be used out in the city. Students became leaders and produced projects I never imagined possible," said Johnson, who was honored as Citizen of the Year by the Menomonie Urban Forestry Board in 2021.

Students produced more than 20 city benches from the repurposed ash wood between 2018 and 2021, when Johnson retired and Dietsche stepped in to take his place. "This project has impacted how I teach. It follows a high-impact practices model (HIPS), which reinforces the importance of partnerships and hands-on activities, creating a whole team of student leaders," Dietsche said.

"This project is something special. We're able to take something dead and dying and give back to the city, with an end goal of showing kids the engineering process - from mechanical and technical to packaging. The real key is connecting people to people," he added.

Dietsche plans to continue similar projects with the addition of artificial intelligence and circular design practices in the research and development, as well as construction and repair processes.

Graduates from UW-Stout's mechanical and manufacturing engineering programs reported 99.5% employment rate within six months of graduation and an average starting salary of more than $70,000, according to the latest university First Destination Report.

UW-Stout's Robert F. Cervenka School of Engineering is home to five ABET-accredited programs that also include computer and electrical engineering, engineering technology and plastics engineering, as well as a sixth bachelor's program in packaging. A master's in manufacturing engineering is available on campus or online.

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