In this Take Apart Lab, Morgan, Gabby, and I took apart the Bio-Rad Econo Recorder Model 1325, a flat-bed chart recorder for use in laboratory settings (Figure 1). This blog post will provide a high-level overview of the process and takeaways learned from this lab.
Figure 1: Assembled Bio-Rad Econo Recorder Model 1325
To begin taking apart the device, we first opened the battery compartment without tools since it was a simple snap joint made of plastic. Inside, we found a spare fuse (Figure 2). We understood this to mean that this device was intended to be repaired by the user instead of discarded in the case of a blown fuse. This is a considerate design feature since laboratory equipment is often quite expensive, so features that increase the lifespan of the product would greatly benefit the user.
Figure 2: Battery compartment with spare fuse
We then removed the screws holding together the outer plastic casing using a combination of Phillips and flathead screwdrivers. Since it was relatively easy to disassemble this part of the device and with common appliances, we deduced that the outer casing was designed to be disassembled. Our suspicions were confirmed once we saw the fuse, which was housed on a printed circuit board (PCB) (Figure 3). As such, this device was designed to be disassembled for repair purposes.
Figure 3: PCBs with the fuse indicated by the red arrow
The PCBs were custom-designed and then sent to a manufacturer for assembly. The components (resistors, capacitors, etc.), however, were likely off-the-shelf parts that were soldered on by the manufacturer.
We further disassembled the device by removing the top PCB off of the standoffs using a Phillips screwdriver (Figure 4). The presence of these plastic standoffs that were aligned with the PCBs led us to believe that the plastic outer casings were custom-made using injection molding. In order to have such precise compatibility with the custom-made PCBs, the casing and associated standoffs were likely custom-made as well. However, all of the screws that were required to fasten the PCB to the standoffs, outer casing, etc. were likely off-the-shelf parts.
Figure 4: Plastic standoff which separates the PCBs
Underneath the top PCB, we noted a metal box that had no screws or other fasteners to open it. After some difficulty attempting to brute force it open with pliers, we noticed a DC motor inside (shoutout MECH 488) (Figure 5). This metal box was designed to not be taken apart to prevent damage to the motor and/or its connections, as the motor is an integral part of the functionality of this device.
Figure 5: DC motor in a metal box
Lastly, we identified a pulley system that is used to control the location of the pen (Figure 6). This pulley system was assembled with another DC motor, two gears, and some string. The motor is an off-the-shelf part sourced from Maxon, and I hypothesize the gears and string are off-the-shelf parts as well.
Figure 6: Pulley system
An interesting takeaway from the disassembly of this device was that ~70% of the device’s weight stemmed from the outer casings. Since these were made of plastic, it is possible that these components could be recycled. Other components, such as the gears, motors, and screws, can be repurposed for other uses. Another interesting observation was that there were 37 screws used in the assembly of this device. The use of so many of these fasteners once again suggests that this device was intended to be disassembled and reassembled.
During this lab, I came to realize that complex designs can be manufactured using simple parts. For example, the system designed to move the pen on the chart paper was created with a simple gear system and string. Additionally, many of the different components were connected with screws and washers.
All in all, this lab was a valuable learning experience to understand how things are assembled and why they may have been created in a certain way. This was my first time taking apart a device (except for nearly all my pens in elementary school), and I gained a new perspective from this experience.
Worksheets:
Parts and Design Feature Analyses
Clean work station
