Throwback Thursday with The Chain Train

Happy Throwback Thursday! This week we interviewed Christopher Song of The Chain Train. This team worked on developing a tool-less chain tensioner to improve TTI’s RYOBI One+ Chainsaws.

Q: Could you give us a brief description of your project for those who may not know about it?

A: TTI wanted us to redesign the toolless chainsaw tensioning mechanism on their Ryobi ONE+ chainsaw. There were complaints about the tool-less tensioner not providing a sufficient tensioning range and not having as much tensioning precision as the tooled tensioner variant. We needed to design a tensioning mechanism that tensions the chain more effectively than the current toolless chain tensioner, that could provide user feedback, and could be retrofitted to the current chainsaw body. Ideally, this tensioner should incorporate the reliability of the tooled tensioner, but incorporate the ergonomics of the current tool-less chain tensioner.


Q: Where did you first draw inspiration for the idea of the “Tool-less Chain Tensioner design,” for your Capstone Design Project?

A: A lot of our initial inspiration came from analyzing tensioning mechanisms from other chainsaws and other devices, such as automatic tensioners found in bikes and cars. One general theme we noticed was that most chainsaws tension their chains by moving the guide bar by rotating either a knob or a screw, which prompted the use of a scotch yoke mechanism.


Q: What was the design process like and how did you and your teammates come together to finish your project?

A: We first delegated specific roles for each of the team members that played to their own strengths. This helped to evenly distribute the workload throughout the whole semester. Our process was as follows: concept ideation, testing/data collection, hand calculations, FEA simulation, 3D print prototyping, metal prototyping. We first came up with a few design concepts to carry out the basic functions of a toolless chain tensioner and created models in CAD with various combinations of our ideas. After, we collected load force samples to determine the worst-case scenario stress loads that could be applied to our design. In addition to hand calculations we also used FEA simulations to validate our theoretical calculated stresses on the design parts. We then move to fit testing and prototyping with 3D printed parts which served as trials before final metal parts. Having each person assigned to a specific role or specialty knowledge area really helped our team and project flow smoothly.


Q: What were some of the problems that you faced along the way and how did you overcome those obstacles?

A: During the concept ideation and testing phase, several group members had to quarantine which prevented us from gathering and fit testing the 3D printed parts. This prompted us to shift all hands on work to only engineering analysis work and research. This caused minor interruptions in the timeline; however, we were still able to manufacture multiple prototype iterations despite this.

Another issue that set back our timeline was the HIVE messing up and delaying multiple prints. Our progress heavily depended on these delayed parts, so we reached out to other makerspaces like the invention studio an Aero makerspace to try to get the parts printed ASAP. We explained the situation to TTI, and they offered to help print parts for us. Luckily, with and help from TTI and other makerspaces, we were still able to make the fit-test prototypes we wanted. From this, we learned to reach out to multiple resources simultaneously, and it is wise to have duplicate prints (just incase one turns out poorly).



Q: How did it feel to present your project virtually?

A: With the first few people that showed up to our online table, we were a little bit flustered. It was hard to see when someone had joined the table huddle, so someone had to constantly monitor the head count. We also talked over one another answering follow up questions. After the first couple people, we sorted out how to approach the follow up questions by having one team member vocally saying “I’ll take this” or redirecting by saying “I think [team member] can answer this.


Q: How did it feel to work with TTI and how did they help you with the creation of your project?

A: The TTI engineers who worked with us were very kind, knowledgeable, and a great resource to our group. We are very thankful for the engineers at TTI who guided us through this project and offered insight/advice. During our concept ideation phase, TTI helped us understand what kind of materials were realistic for this project, what design concepts would be more feasible, or the codes and standards that were applicable. The team was very nice; they went as far as to print some 3D parts for us and ship them to us when the on campus resources were slow and queued up.


Q: What do you think made your team successful in creating your project?

A: Members of the chain train have had prior design experience from participating on SCC teams and past internships which allows us to have a diverse skillset. The diverse skillset allowed each member to excel at what they do best, while helping to cover other members’ weak spots. With six people on our team, we also had a lot of different ideas a different point of views. By having so many POVs, we were able to come up with many ideas and really analyze the pros and cons of each idea in depth. Also, we had a great advisor and a ton of help from the engineers at TTI.


Q: Do you have any advice for future teams?

A: Aim high and have checkpoints/a clear direction that the team is heading towards. This allows the team to finish a bulk of the before the deadline. For example, our team wanted a fully working developed design that was ready for production by the end of the semester. Although we could not achieve this goal, our timeline allowed us to finish a working prototype with a mix of metal and 3D printed parts. The design still needs improvement, but our work will help TTI fast track the next design for their next toolless chain tensioner.

When meeting with the sponsor, prepare a short weekly/ bi-weekly presentation for the engineers. This keeps meetings short and informative. During the meeting, assign a designated note taker to record any comments/ feedback from the sponsor.

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