Group 24 - Swingline Electric Stapler
The purpose of this page is to provide a detailed product analysis of the Personal Electric Stapler manufactured and designed by Swingline.
Our stapler converts electric power to mechanical energy using a motor, a system of gears and a circuit board. When a small sensor is depressed in the mouth of the stapler by the packet of papers, it sends a signal to the circuit board which engages the motor. The motor spins a series of gears and the end result is a successfully stapled packet of papers.
To better understand how this process worked we all disassembled the stapler. After seperating the main components we created a disassembly table and a parts list. And we also created a 3D CAD Drawing to help explain the motion of the moving parts.
Reassembly proved more difficult than the disassembly because we cut the wires connecting the motor to the circuit board. We had to splice these back together and find a place for them.
In the After Assembly section of this report you will our recommendations for improvements and our final conclusion.
The Swingline Personal Electric Stapler is a popular office appliance with a retail price of $39.95. It can staple up to 15 pages at one time, runs on both AC and battery power, and holds 210 staples.
Group 24 Members
- David Sheffield (Group Leader)
- Joe Marzello
- Nick Rhode
- Shawn Hammerton
- Mark Okraksinkski
The product that our group was assigned was an electric stapler made by Swingline. Before disassembling the product, our knowledge was very limited in how it works or the components inside. However, we can make several obvious assumptions from current knowledge of staplers. The purpose of an electric stapler is to staple pages together or to bind two pages or more pages together. This is useful because in a report several pages long, they can be kept organized chronologically and won’t be separated from each other. An electric stapler is more advanced than your regular stapler because instead of using your hand to push the staple in the page, it is automatically done for you. You slide your pages under the designated area, the stapler triggers, and activates a staple binding your pages.
Our knowledge was limited in how the stapler works, what components it may entail, and what different materials are used. We know that it uses electrical components such as wires and a switch board because it needs the electrical energy to transfer it into mechanical energy. This mechanical energy is the part that actually does the stapling. In order to accomplish this, it must have some mechanism to drive the staple into the paper. We also know that a small motor is used to power this mechanism and the motor is powered by our electrical energy. We can predict that the system may use gears to transfer motion, but we are not sure of the orientation or how many. The materials used in the production of the stapler are hard to predict because many materials would be feasible solutions. We do in fact know that plastic is used for the protective casing. The other materials that we assume are used in some components would be steel and magnets for the motor and other types of metal for smaller components that need to be strong such as screws.
When we received the product we tested it out and it did work. We plugged it into the wall using the electricity from the outlet and put batteries in the bottom of it. Both methods worked and let the stapler run flawlessly. It did emit a sound from all the movement that was going on underneath the protective casing. The sound was not like a normal stapler but more forceful and fast paced. You could hear some components moving around and then the louder sound of something drive the staple down.
The motor spins at a high rate of speed and through gear reduction it spins the large gear (2) causing the swing arm to pivot, therefore forcing the piece of metal down that pushes the staple into the paper. The video below will help.
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Disassembly Process Table
|Step #||Process||Tool(s)||Level of Difficulty|
|1||Remove the black feet revealing the four screws on the bottom plate||Hand||Easy|
|2||Unscrew those four screws||Hand and phillips head screwdirver||Easy|
|3||The shell base can now be seperated from the bottom plate||Hand||Easy|
|4||This exposes numerous wires, you can unhook the paper sensor and power jack. To do this just pull lightlty on them||Hand||Easy|
|5||The top protective case can now be removed from the shell base by pulling up, you may need to wiggle it.||Hand||Easy|
|6||You will notice that the top case cannot be fully seperated because it is attatched by wires. You can simply cut the three wires to completely free the piece.||Hand and wire cutters||Easy|
|7||Unscrew the eight screws and remove the washers that hold down the motor mount.||Hand and phillips head screwdriver||Easy|
|8||Unscrew the two screws (gearbox scews b) on the side of the gearbox that are holding the brace and gear a in place. The brace and gearbox a will easily come off.||Hand and phillips head screwdriver||Medium|
|9||The whole assembly of the gearbox and swingarm mount can be lifted from the shell base and taken out to free up some space||Hand||Easy|
|10||With the gearbox and swingarm out of the shell base you can further dissassble them. Unscrew the two screws (gearbox scews a) on the top edge that will seperate the motor mount into two halves||Hand and phillips head screwdriver||Easy|
|11||Slide the two external gears (a and b) off the drive shaft||Hand||Easy|
|12||The motor and swing arm lever/mount can now be freed from the motor mount||Hand||Easy|
|13||The swing mount gets further disassembled by detatching the swing are lever.||Hand||Easy|
|14||Remove the two slip washers on the outsdie of the swing arm mount||Hand||Medium|
|15||Slide the swing arm pivot bar and spacer ring out of the swing arm lever||Hand||Easy|
|16||Unscrew the screw that is fastening the swing arm head to the staple contact head mount and swing arm head.||Hand and phillips head screwdriver||Easy|
|17||Moving back into the shell base; The circuit board is resting in a grove and can now be removed by lifting up||Hand||Easy|
|18||Flip the shell base upside down, remove the spring loaded spring on top of the pin and the washer||Hand||Medium|
|19||Mount the strike plate onto the shell base with two screws (strike plate screws)||Hand and phillips head screwdriver||Easy|
|20||On the same end as the strike plate there is a screw holding the staple tray to the shell base; unscrew that||Hand and phillips head screwdriver||Easy|
|21||The whole staple tray can now be removed from the shell base by lifting it out of its groves||Hand||Easy|
|22||Unhook the large spring to the staple tray||Hand||Easy|
|23||Remove the small spring mounting pin which will free the small tray spring||Hand||Easy|
|24||Remove the mounting pin which will free the tray release switch and small tray spring||Hand||Easy|
|Part No.||Part Name and Function||# Of This Type||Material and Reason for Choice of Material||Reason for Part's Shape||Manufacturing Process|
|1||Gear A (transfer energy from gear B to gear C)||1||Nylon, because it reduces friction||The radius and the number/size of teeth were chosen for the proper gear ratio for energy transfer||Injection molding|
|2||Gear B (transfer energy from the motor to gear A)||1||Nylon, because it reduces friction||The radius and the number/size of teeth were chosen for the proper gear ratio for energy transfer||Injection molding|
|3||Gear C (transfer energy from gear A to the cam wheel)||2||Nylon, because it reduces friction||The radius and the number/size of teeth were chosen for the proper gear ratio for energy transfer||Injection molding|
|4||Gearbox Screw A. (holds together the right and left halves of the gear box mount)||2||1020-1040 steel. it provides adequate strength while maintaining low cost||Thread spacing and precision chosen because they don't need to withstand any degree of strong vibration. screw length is chosen because the screw needs to fit deep enough into the to hold the parts together.||Extrusion and Cold Forging|
|5||Gearbox Screw A. (hold the brace to the gearbox mount)||2||1020-1040 steel. it provides adequate strength while maintaining low cost||Thread spacing and precision chosen because they don't need to withstand any degree of strong vibration. screw length is chosen because the screw needs to fit through the brace and into the hole in the gear box mount.||Extrusion and Cold Forging|
|6||Brace (prevents gear A from slipping out of position)||1||Nylon. It allows the brace to secure the gear without causing too much friction.||The length of the brace needs to be wider than gear A so that its mounting doesn't interfere with the rotation of gear A. the hole in the center of the brace allows the gear shaft to fit and thus preventing excessive vibration.||Injection molded|
|7||Cam Wheel (creates a large turning radius to operate the swing arm lever.)||2||Nylon/ABS plastic. The right half of the Cam wheel is made of nylon because it is the part that originates the movement and therefore needs to cut down on friction. The left half of the Cam wheel is made of ABS plastics because all it has to do is attach itself to the right gearbox mount.||The large diameter of the wheel allows for precise control over the motion of the swing arm lever. The ribs in the material act as spokes to strengthen the wheel without adding unnecessary material.||Injection Molding|
|8||Electric Motor (converts electrical energy to mechanical energy, initiating the motion in the stapler)||1||Copper wire and leads (good electrical conductivity), ABS plastic rear(shock resistant, insulator), Steel drive shaft (sturdy material), Galvanized steel case (rust resistant).||The electric motor is made up of coiled copper wire that creates a magnetic field that is surrounded by 2 permanent magnets. The opposing magnetic fields cause the coiled wires and the drive shaft to spin. All of this is encased in a steel frame with a plastic base .||Extruded (wire, drive shaft), Injection molded (base), Formed (case, wire).|
|9||Gearbox sensor (tells the circuit when to stop the motor)||1||ABS plastic (cheap and strong enough to support the spring), steel(is flexible)||The lever on the end of the sensor allows for maximum sensitivity. A strong spring allows the timing returned to the circuit to be precise.||Injection molded (plastic), Extruded (steel)|
|10||Gearbox mount(right)(provides a place to mount gears A,B,and C, the right half of the cam wheel, and the brace)||1||ABS plastic (cheap and strong enough to hold things together)||The shape is designed to make all the gears fit together, to align with the Gearbox mount (left), and to fit on the shell bottom||Injection molded.|
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Assembly Process Table
|Step #||Process||Tool(s)||Level of Difficulty|
|1||Align the swing arm in between the left and right sides of the motor mount. The longer whole on the swing arm lever should be over the pin between the black wheel and the white wheel||Hand||Easy|
|2||Align right and left half sides of the motor mount with motor||Hand||Easy|
|3||Secured two halves of the gear box together with two screws on the top edge (gearbox screws a.)||Hand and phillips head screwdriver||Easy|
|4||Attach two external gears (a and b) to the outside of the motor mount. They easily slide onto drive shafts.||Hand||Easy|
|5||Mount brace over bigger gear a. Then secure it with two screws (gearbox screws b.)||Hand and phillips head screwdriver||Easy|
|6||Mount staple contact head onto the swing arm head||Hand||Easy|
|7||Mount staple contact head mounting bracket onto the swing arm head. Secure this in with a a screw (staple contact head mounting screw)||Hand and phillips head screwdriver||Easy|
|8||Align swing arm head with whole on the swing arm mount||Hand||Easy|
|9||Slide spacer ring into smaller whole on the swing arm lever then secure with swing arm pivot bar as a pin||Hand||Medium|
|10||Secure with the two slip washers on the outside of the swing arm mount||Hand||Medium|
|11||Attach large spring to the staple tray just by hooking it on||Hand||Easy|
|12||Align tray release switch and small tray spring, then secure by sliding the tray release mounting pin through the aligned holes||Hand||Easy|
|12||Tension and secure the small tray spring with the small spring mounting pin||Hand||Easy|
|13||Mount the strike plate on the shell base. Secure down with two screws (strike plate screws)||Hand and phillips head screwdriver||Easy|
|14||Place staple tray in the shell base. Make sure the larger pin on the staple tray falls into the groove in the shell base. Slide pin over to one side and put screw into whole so that the pin will not slide anywhere||Hand and phillips head screwdriver||Easy|
|15||Flip the shell base upside down, place spring on top of pin from the staple tray and secure with slip washer||Hand||Medium|
|16||Place circuit board into the grooves in the shell base. The circuit components should be facing the rear of the shell base.||Hand||Easy|
|17||Align the motor mount and swing arm mount with the screw holes on the shell base. Note that the tray has to be in the open position, to do this push the staple tray release switch forward.||Hand||Easy|
|18||Fasten this down to the shell base with eight washers and eight screws. The screws are tricky to reach with the screw driver, it will be easier if you remove the brace from the side of the motor mount. Just remember to reattach the brace after you finish screwing down all the screws||Hand and phillips head screwdriver||Medium|
|19||Connect the wires from the circuit board to the switch and motor. Use colors to match them up||Hand and wire cutters||Hard|
|20||Place top protective casing over the top of motor (make sure the circuit board and wholes are lined up and that the switch and button are lined up) and snap it into place||Hand||Easy|
|21||Secure the top plate to the shell base with two screws||Hand and phillips head screwdriver||Easy|
|22||Place electronic components on the underside of the shell base. Snap the paper sensor into slot on bottom side of shell base and attach power jack to bottom plate.||Hand||Easy|
|23||Snap the bottom plate to the shell base, fasten with four screws (make sure all wires are tucked in neatly)||Hand and phillips head screwdriver||Easy|
|24||Place black feet over the screws on the bottom plate to hide the screws||Hand||Easy|
|25||Snap battery protective casing to the bottom plate||Hand||Easy|
Disassembly of the Swingline Personal Electric Stapler was a relatively easy task only taking about 2 hours. All that was needed to disassemble was a small Philips head screw driver and a pair of wire cutters. Once the outside case was removed from the stapler, all of the inner workings could be seen inside. The stapler had many more moving parts and gears than initially anticipated. There were 5 gears used for gear reduction in between the motor and the swing arm that pushed the staples into the paper. There were only two difficulties during disassembly. The first was how to remove things that were attached with wires such as the motor, L.E.D., and the circuit board. We weren’t sure if we could cut the wires because we didn’t know if they had enough slack in them to splice back together during reassembly. We decided to cut the wires because we found a way to get enough slack in them to splice the wires back together. The second difficulty was removing the snap ring that held the spring under the staple tray. The first time it was removed it shot across the desk and was luckily found. On a scale of 1 to 10 with 10 being the hardest we would rate disassembly of the stapler as a 3.
Overall the stapler was very well designed and served its purpose very well. However, there were a few improvements we thought that Swingline could implement that would make the stapler even better. The first improvement is that the stapler could be made more compact. If the gear ratio and motor were changed slightly this would free up some space within the main compartment. The staple tray could also be made shorter. Doing both of these things in the stapler would take about an inch off of the overall length and a half an inch off of the width. A smaller stapler would take up less room on a desk, something everyone would like. The second improvement is giving the stapler a built in rechargeable Ni-Mh battery. This would make the stapler more portable and would eliminate a cord from an already crowded desk. A rechargeable feature would also save the user from needing to go out and purchasing the currently required two batteries. Making the stapler more convenient would help the stapler sell better, therefore, making Swingline more money.
An analysis in ergonomics, stress, and strength of the product and its components can be used to aid in the design and testing phases. An ergonomic analysis could be used to design a stapler that would better fit the space constraints of an office desk, to include a power cord long enough for the average user, and to design a staple tray that would allow easy reloading of staples. Stress and strength testing on the motor and gear box could be used to design the stapler that would be able to staple through a large amount of pages as well as ensure components stable enough so the product will still function even if dropped or struck. A basic engineering model that could be used would be a CAD drawing of the stapler and its components as well as an actual working model as the scale of the stapler is small enough to do so. For the stapler to function the components must fit together with very little error so it would be appropriate to use precise modeling.