Jar Opener

The following design is my Mechanical Engineering junior design (ME 340) project. I was sorted into a group of three and given an 18V cordless drill. My team and I were assigned to dissect the drill and learn more about the gear train. Then, using our knowledge of the drill dissection, we were to take those gears and 18V battery and construct a semi-automatic jar opener for extreme users (i.e. users that only had use of one of their hands). After constructing an alpha and beta prototype, my team was expected to present a formal presentation to our fellow classmates and then vote upon which team's jar opener was the most efficient.

This class served as the first real Mechanical Engineering course that introduced the design process to me and how to apply it to various projects. On top of the project, we were expected to submit design reports based on our progress. Attached is the final design report of the project, clearly depicting the various steps to acquire customer needs, engineering specifications, necessary calculations, and instructions for complete manufacturing, as well as reflections on the specific design and how it performed.

Here are the steps that were followed during this design process:

1. Analyze: The team was given the data that rheumatoid arthritis is more prevalent than ever with elderly population, and opening jars has become an issue. The specifications required an extreme user to be able to use this jar opener; that means we had to keep in mind how to use our product with one hand. The trickier part was that it not only had to open jars but close them as well. A good starting point was dissecting the cordless drill we were given and analyze its internal workings. The drill had a specific gear train that allowed it to go in two directions (screw and unscrew). It also provided our group with an 18V battery, which would be our power source. After doing an external search, customer survey, and patent search, we felt , we analyzed what we were given and what we needed to do, so it was time to come up with designs.

2. Brainstorm: One method that was taught to use in our design methodology course was the "Post-It Method." It involves every group member getting Post-It notes and, no matter how obscure or ridiculous the idea, everyone would write each idea on a Post-It note. Then putting all the Post-It notes on the table, each member had five or so votes and would vote on five ideas they like best. The top three ideas that had the most votes would then get considered as a possibility to go forth with the design. The initial idea that was favored by the team was the "two-cone" idea. Essentially, the consumer would place their jar in between two cones that were covered in a thick rubber (which would aid in gripping the jar). When the user turned the device on, the cones would both spin in opposite directions, which the team calculated would provide each friction and torque so the lid of the jar can pop open. When the user wanted to put the lid back on, the user would turn a switch and the cones would spin in opposite directions, allowing for the lid to be fastened back on.

3. Develop: The first phase of the project was to construct an alpha prototype, just to demonstrate the concept of the team's design. Using the metal workshop at Penn State (called the Learning Factory), the team and I sawed, milled, turned, and constructed the alpha prototype.

4. Test: After many hours of work, my team and I completed the alpha prototype... But there was a problem - it did not work.

The jar would go in between the two cones and the cones would spin; however, the rubber on the cones did not support or grip the base of the jar enough, which meant the jar just spun as the two cones spun. What was my group going to do? There were two options: option A was to continue with this design and try to make it work for the beta prototype, or option B was to go back to the brainstorming phase and come up with a better concept that would work. If we went back, my group assumed that all our work would be for nothing; however, after evaluating the situation, it was decided that option B was the best option. Sure, we could have gone with option A and possibly had a working prototype, but what was the risk? Is taking an idea that does not work initially and trying to make it work a good option? What if the final product still did not work? Even though this was a classroom project, we were instructed to think like real engineers - in the real world, would you risk trying to rush a bad product out, or would you do the tough decision of spending even more hours to come up with a design that actually works? We laid out the options, and even though option A was the easier choice, as an engineer set out to make safe, quality, and functioning products, it was decided to go back to the brainstorming phase.

5. Brainstorm (Again): Was all the past work we did on the project for nothing? Initially that is what the group and I thought, but we realized it wasn't - the preliminary calculations could still be applied to this new design. What didn't work with the initial design? As mentioned before, the jar's base just was not gripped enough by the cones... So how do you fix this? We decided inside of a bottom cone, we would apply an oil wrench, as seen below in Figure 17.

Figure 17: Oil Wrench

The oil wrench was an ingenious concept - as the jar would spin, the oil wrench would also spin and have the arms close in on the jar. Once the arms clamped to the jar, the oil wrench would stop spinning and that would allow the top cone (which was continuously spinning) enough support and torque to pop off the lid. If the user wanted to put the lid back on, the jar would spin in the opposite direction. The oil wrench would release the jar and spin in the other direction, allowing the arms to, once again, slowly clamp to the bar of the jar. The top cone would still spin and be able to twist the lid back onto the jar. The concept was still basically the same as the first idea but with better implementation. At the last minute, the team and I decided to change the top cone into a claw; the claw was angled where any size jar could fit inside (small or big), and using the concept from the first idea, rubber was attacked to the claw to provide friction and grip. In the report, we mention the use of a cone on top instead of a claw, but due to our available resources, for the beta prototype it was more applicable to use a claw.

6. Develop (Again): The team and I went back to the Learning Factory to construct a beta prototype. Using the water jet cutter to make the claw and soldering wires together to connect the gear train and the battery (migrated from the alpha prototype), my group built a beta prototype. The next step of the process was crucial - would it work after this complete redesign?

7. Test (Again): The initial testing proved successful - the beta prototype was able to open and close various-sized jars.

5. Improve: Now that the design is working, what could be done to make it even better? There were a few changes from the professor's input that were implemented - the battery holder was not very aesthetically pleasing, so our group resigned the battery holder. Not only did the battery become 'invisible' to the user, but it became more secure/durable. A few other suggestions were with the alignment of the user handle with the project and some other minor tweaks.

Conclusion

This project was very important to me because it was the first time I applied my knowledge in Mechanical Engineering to make a working prototype. In previous classes, I have been doing either SolidWorks drawings or preliminary calculations; in ME 340, you not only do the preliminary planning, but you then implement those concepts and see if what you did works. In the case of my team, we used our knowledge to make an initial idea which proved unsuccessful. Thinking like a real world engineer, the best option (even though it was the most difficult) was to redo our design to make it work (instead of taking a failed idea and trying to make it work). With all our determination, we completed a successful beta prototype and improved it to the point where the class awarded our design, "Consumer's Choice." Our prototype worked the fastest at opening and closing jars and was the most aesthetically pleasing. So, even though taking a few steps took more hours of work, was it worth it? Was it able to produce a top quality and functioning prototype?

Absolutely.

If the team and I went ahead with our original idea, who knows if it would have worked at the end of the semester - and then what? What would we have done? This project taught me how to deal with failures - do you give up, or do you try to figure out the problem and start from there? As engineers, our top priority is making a safe and functioning prototype - and this design helped me realize that this design process helps assure a successful project.