Embedded Files
This project is a continuation of my junior design project where we developed a device to help fishers set the drag on their reels. I was in a group with five total mechanical engineers, and I lead the mechanical design.
Problem Definition: The current method of setting drag on a fishing reel is inaccurate and usually requires two people.
Drag is the friction force on a fishing reel that controls the tension in the line. If the drag is set too high, the line will snap and the fisher will lose the fish and any tackle attached to the end of their line. If the drag is set too low, the fish will not tire and the fisher is not optimally utilizing the strength of their line.
Improvements from junior design project: Our goal is to develop a rod-mounted drag measuring device that does not rely on wall power.
🏆 Outstanding Innovation in Mechanical Engineering
🏆 Best ME Capstone Video
Our team was among 13 mechanical engineering capstone teams up for 4 awards (we received 2 of the 4).
Concept
CAD Render
Initial Prototype
Redesign Concept
CAD Render
Final Prototype
Operating Principle
We selected a three-roller system to measure line tension inspired by industrial cable tension measurement systems. The center roller is compliant and its displacement in relation to tension can be approximated analytically, but the physical system will need to be calibrated to improve accuracy.
Initial Design
CAD Sketch
Prior to any assembly modeling, I created a sketch laying out the full motion system as well as bolt patterns and the footprint of the device. This serves as the foundational sketch for the housing components and allows for easy dimensional changes.
Mechanism
Linear displacement of the main roller is amplified through the pinion/pulley system. The live tension indicator is adhered to the top side of the belt which displaces the maximum tension indicator. The maximum tension indicator is to be manually reset as needed.
Finite Element Analysis (FEA)
Lid
Loading: Reaction force for idler rollers with 15lb line tension
Maximum Stress: 11.13 MPa
Formlabs Standard Resin Yield Strength = 61 MPa
Safety Factor ≈ 5
Main Housing
Loading: Reaction force for main roller with 15lb line tension
Maximum Stress: 5.89 MPa
Formlabs Standard Resin Yield Strength = 61 MPa
Safety Factor ≈ 10
Yielding is the failure mode for our analysis because plastic deformation of the rollers will cause an unknown error in our line tension readings. The housing components will be prototyped using a Formlabs SLA printer, but they have been designed with injection molding in mind.
Initial Design Physical Prototyping
Initial design flaws and attempted solutions
Belt stretched more than anticipated → purchase a smaller belt
SLA 3D printed rack and pinion didn't mesh properly → implement an off-the-shelf rack and pinion
Pinion would deflect away from the rack → support pinion on both sides
Belt path has significantly more friction than anticipated → introduce bearings to all rotating components
This prototyping process resulted in us creating a device that worked but unreliably and it felt over-engineered. By this point, it was the beginning of spring quarter and we had 3 weeks until our functioning prototype was due so we looked towards other options for creating our device.
Redesign
The goal of the previous mechanism was to translate a small displacement into a larger displacement. Dial indicators already do this, so by incorporating a dial indicator into our design, we can create the features we planned for our original design with the precision of a mass-produced mechanism. This pivot also significantly reduces the anticipated cost of our device from $15 to $7.50.
Redesign Iterations
Proof of concept
Refined design with 20° viewing angle
Final device
Because we only had 3 weeks to create a functional prototype, we had 3 group members working on different concepts for the dial indicator prototype. I designed the fixed viewing angle model which we ended up using for the final device.
Feature Demo
Maximum tension indicator
Rod clamping mechanism
Testing
Calibration
To create the scale for our device, we used a hydraulic press with a load cell to pull fishing line mounted through the device. We noted the needle deflection at half-pound increments.
Break Test
The purpose of this device is to help fishers prevent line breakage, so we wanted to test that our device does not impact line strength. To do so, we ran 20 total trials breaking fishing line with and without our device and performed statistical analysis where we determined that our device has no significant impact on line strength.
Specifications
At the beginning of this project, we defined a set of minimum specifications for our device, and we hit all of the specs we tested.
Capstone Poster
New Venture Competition
In addition to capstone, our team also participated in the New Venture Competition (NVC) through UCSB. For this competition, we conducted market validation by interviewing over 30 fishers, formulated our business model, and quantified the market for our product. This experience was great for understanding product development beyond the engineering side.
NVC Poster
Google Sites
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