This picture is from Amazon.com

The machine assigned to our group (Wen-Yi, Xinyin, and Yifan) for disassembly was an EPSON LX-300+ dot matrix printer. Dot matrix printers are primarily used for printing invoices, reports, shipping orders, and other documents that require multiple copies or long-term durability. They function similarly to traditional typewriters: needles in the printhead strike an ink ribbon, transferring ink onto paper to form text or graphics.

The machine we received was slightly different from the reference images we found online—it was missing the cover and ink ribbon. We speculated that these components were designed to be easily removable, allowing users to replace the ink ribbon or address paper jams with minimal effort. This could explain why these parts were absent when we received the machine.

We spent approximately two and a half hours disassembling our machine (1 hour in class and 1.5 hours on 1/26). The image below shows what our printer looked like before it was taken apart.

To begin the disassembly process, we first closely examined the machine. We started by removing parts that could be detached by hand, such as the paper guide and cable. Before proceeding with further disassembly, we observed the movement of the printhead in relation to the surrounding gear structure. (As the video below shows) This step helped us better understand how the printhead was driven when the printer was in operation.

Next, we attempted to disassemble the printhead and its cable, but we were unable to proceed further because the cable was connected to deeper structures.

We then removed the screws securing the outer plastic shell. Once the shell was detached, we uncovered a more complex internal structure. We continued to remove the screws to remove the next layer of metal board. At this stage, we effectively divided the printer into two main sections:
1. The upper part: contained metal board with paper rollers, carriage belt, etc.
2. The lower part: contained plastic bottom shell and metal board with motherboards(Printed Circuit Board, PCB).

We then worked together to disassemble the upper part, which contained numerous screws of varying sizes. Some screws were extremely tight, making them difficult to remove. To address this, we experimented with different screwdriver sizes to find the most suitable one. In this section we found many interesting structures:
a. Gears, paper feed shaft, and the paper rollers- Here, we observed a gear set and a snap-fit structure. We tried several ways to remove the gear, but finally we just forcibly broke the snap-fit structure.

 

 

b. Stepper motor- We inferred that this component converted electrical energy into rotational motion.

c. Mortise and tenon structures– We discovered that many parts in this section were assembled using mortise and tenon joints.

Disassembling the lower section was relatively straightforward, primarily involving the removal of screws and the cutting of wires. The only major challenge we encountered was figuring out how to remove a mushroom-shaped screw, which tightly fastened a circuit board, a metal sheet and the bottom plastic shell together. While trying to remove it, we accidentally broke the circuit board. To resolve this, we first used wire cutters to remove the remaining fragment of the broken circuit board. Then, we used pliers to unscrew the stubborn mushroom-shaped screw. Given the complexity of removing these screws, I believe our machine was not designed to be easily disassembled.

 

After completing the disassembly, we classified the parts by material, size, and function, and then weighed them, as shown in the following pictures.

Upon sorting all the parts, we discovered that certain components, like screws and gears, were off-the-shelf items. However, the majority of parts, such as plastic casings, circuit boards, and metal sheets, were custom-made for this printer. The primary materials used in this machine were plastic, comprising 32.82% of the total weight, and metal sheets, accounting for 35.64%. These materials appeared to be recyclable. Nevertheless, our research indicated that ink ribbons are more challenging to recycle and may pose greater environmental harm.

To be honest, my parents own a plastic injection molding factory in Taiwan, so I had some prior knowledge of mechanical assembly and industrial design before taking this class. However, through this take apart lab, conducting research and discussing with my teammates, I realized that the factors involved in designing and assembling a machine are far more complex than I had imagined. I’m grateful for this opportunity to gain a deeper understanding of the intricacies behind mechanical assembly.

Links to our worksheets:
1. https://docs.google.com/document/d/1xW_NBAGiISjaGeYfSQhi5sZKT-WAZVyx/edit?usp=sharing&ouid=111877443806684292768&rtpof=true&sd=true
2. https://docs.google.com/spreadsheets/d/1BgrgQNIN1bVUD63QjBHd1yaYML3DNNwtvXDR0A-zd6c/edit?usp=sharing

Pictures of our clean workplace after take apart lab:
1. 2.