The machine my group disassembled was the sewing machine, used by millions of people around the world to convert raw materials into highly usable products.
Image 1: First step of removing the face cover, exposing the complex inner mechanism of the machine.
Image 2: Removed the base and corresponding screws.
We started by removing the plastic covering the needlepoint area of the machine; then using Philips-head and flat-head screwdrivers, we removed the steel screws holding together the plastic frame of the machine, which wrapped around the cast iron base. There were also associated steel hinges that had been used for easy removal / replacement of string in the machine.
We continued removing these plastic panels and pieces using the screwdrivers, and discovered some of the internal mechanics of the machine including the motor, arm shaft and bobbin holder.
Image 3: Sewing machine laid out on the side revealing the motor, arm shaft, and bobbin holder.
Image 4: Removed all plastic covering, leaving behind only the cast iron frame and inner workings including buttons, gears, and levers
After removing the plastic pieces, we realized the internal mechanics of the machine were largely dependent on a single rod supported by tension springs and a tunable knob for the string tension. There were other attachments using socket screws, such as the motor and two gears to help facilitate the movement of the thread.
Image 5: The meat of our dismantle process where we had to use a variety of screwdrivers, wrenches, and pliers to remove screws, washers, and retaining rings.
Image 6: The meat of our dismantle process where we had to use a variety of screwdrivers, wrenches, and pliers to remove screws, washers, and retaining rings.
We continued removing pieces from the cast iron frame by utilizing Allen wrenches to remove smaller socket screws attaching gears, buttons and other rods to the frame. We faced some difficulty in removing pieces attached by retaining rings, which had been compressed by hand to maintain a tensile force and hold some rods together. By using flathead screwdrivers and pliers, we were able to remove some of these rings.
Image 7: Sewing machine frame laid out including plastic frames, cast iron inner frame, flat bed attachment, motor, and spool with string.
Image 8: Assortment of inner parts of a sewing machine including but not limited to face cover, arm shaft, and needle plate.
Contrary to more recent machines (like MacBooks), the sewing machine was designed to be incredibly modular and easy to open up — it was not difficult to remove some components (like the motor, needle attachments or threads) that would commonly need to be replaced. On the other hand, the heavy oiling and difficulty of access to some socket screws made it clear that not all parts were intended to be easily replaced (especially the attachments held together with retaining rings). It’s likely that durable pieces like the cast iron frame could be preserved in the past while only replacing more feeble parts, but at this point, with the advent of consumerism, there is comparatively limited interest in actually fixing machines as opposed to just buying newer ones. Many of the plastic components can be recycled.
As expected, the cast iron frame and the motor made up over 50% of the overall weight of the machine (~2.4 kg), while other metal components, screws and the plastic frame / gears made up the rest. Iron is quite heavy, and it is most certainly the reason for past sewing machines’ sturdiness. This frame could be manufactured using sand molds and casting, with the use of cores to create spaces in the mold that allow for an accurate construction.
Overall, this lab was quite insightful and helped reveal how devices like sewing machines are manufactured. It was quite interesting to see the inside of a purely mechanical device with no PCB boards or other electronic components. The design considerations involved in making this machine modular help reflect how product users could replace broken parts without having to buy completely new machines.
Image 9: Cleaned workspace after appropriately disposing of parts.
