Coin Sorter

Design Proposal

Best, Aleea Coin Sorter Challenge - Design Proposal

Design Layout

This is the final product of the design and the interior/exterior design of it.

Brainstorming Process

*My initial brainstorming concept and my final product ended up being completely different, as stated in the design proposal.

During this process, I took the time to research some already created designs, any useful information to know, such as the size of the coins and how it will be useful in order to make slots based off it, the FACs, and creating my own ideas on how I would end up carrying out this task.

The Subsystems

I spent most of my time making the hopper system and testing different types of slots for the coins. I did this all separately, and at the end combined all of the parts together.

Here is the initial design of the hopper:

I am cutting out the design of the hopper after measuring and recording the length and angle measurements used. Keep in mind, my design drastically changed as the project got closer to the end.

During this process, I also soldered the motor that will be used as a mechanical aspect of the design. After soldering, I tested the motor to make sure that it was working before I continued on.

The next step was the hardest: creating the slot system. I started by recording the diameter of each of the four coins- quarters, nickels, dimes, and pennies. Afterwards, I tried to free-cut squares and circles that the coins can fall into. I found this particularly hard because it was being hand cut and I was not accurate every time. It also was very time consuming. Here are data entrees from these dates:

The process took a long time and I was not getting the coins to fall through because the slots were inaccurate due to human flaw. Multiple times through this trial and error phase, I switched between circle and square slots. In this photo, it is clearly detectable that the circles were not going to work since I was drawing them without any precise measurement. Since I was experimenting with circles, I decided to switch my work to AutoCAD and RDWorks so that I could get the slots to come out as precise as possible.

I went into AutoCAD and drew out a 240 mm by 30 mm rectangle. Within it, I drew circles down the middle increasing from smallest to largest diameter and having 40 mm of space between each one. While drawing this design out, I realized that the space was too close for the coins with bigger radius. To fix this problem, I redrew the design and increased the distance between each slot. After being satisfied with my drawing, I transferred it to RD Works and used the laser to cut it. After some testing, I quickly learned that it would not work since the circles were down the middle and it was easy for the coins to slide past them. As a result, I attempted to try a rectangular pattern instead, while also using AutoCAD.

Attempt 1:

Using the same measurements as the circle design, I made the first slot system the same width and length. I then left 10 mm of space between the slot and the end so that when the coins role next to it, they will have support on one side, but not the other, making them fall only into their respective slots. An error I made when drawing out this design on AutoCAD was that instead of using the diameter of the coins, I used the radius. This ultimately made the slots too small.

Attempt 2:

I increased the length of the rectangular shape to be 280 mm and the width to be 40 mm. I then made each slot have the height of the diameter of the coins while still keeping the 10 mm of space on the bottom. I made the length of the slots about doubled of their radius so that more coins can fall at a time. The distance between teh coins remained to be 40 mm. When testing, this proved to be successful when it had a support wall next to it.

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Here is the AutoCAD design being cut out by the laser through the assistance of RD Works.

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This is me testing the slot system and its accuracy at different heights.

(At this point, I had limited resources so masking tape was my best friend.)

I then created a box structure in order to hold the different parts together. I made the length rectangle 320 mm by 200 mm and the width 180 mm by 200 mm. After this was created, I realized I needed to build a new hopper since the original one would not work with the box strucutre. I made it so that the coins will slowly tilt and eventaully fall into a narrowed path that leads to the slot system.

The coins are dropped in the middle, and slightly tilt towards one side so that it sets them up for the slot system. When they reach the steeper portion of the hopper, they fall into a little slip which allowed for only one coin at a time and enter the next system. The tape is excessive, fortunately though, the coins do not get stuck on it while they are in the hopper.

The last part of the construction phase was creating the collector system. I ended up putting dividers between each of the slots so that they keep coins separated. Then I cut out holes on the bottom-front where the coins would typically fall out so that they could be grabbed out of the machine.

Here is the final product of the design:

Testing

I initially tested the design in increasing increments. This allowed me to notice any errors in the design before the official tests. During the first test with one of each coins, I noticed that the transition between the hopper and the slot system was too big, making the coins not enter one at a time. After that test, I reconstructed that design and fixed it. Also, during the third test, I noticed that when more coins are accurate, there is a blockage of coins entering the slot system. This also allowed me to assess what the problem is and how to fix it. This problem did not affect accuracy, however it made the coins take longer to go through the system.

Test Results

These tests were testing if the machine will be accurate with four of each coins will be 100% accurate while under 30 seconds. As the data tables show below, the coins entered their slots with 100% accuracy and were able to go through the system in around 20 seconds.

The first data table shows accuracy only. The machine was 100% accurate all four trials.

The second data table tests time and accuracy. The machine was 100% accurate while staying under the time limit of 30 seconds. The average time seconds of all three trials was 19.43 seconds.

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In the video, time and accuracy was being tested. It is represented by the table under Trial 1.

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