Table of Contents
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Phase 3: Detailed Re-Design
Cabinets BenchmarkingAfter the community meeting, it was decided the cabinet concept would be further pursued based on customer feedback. Several cabinet designs were created in order to see the pros and cons of each type of concept. The four types are shown below.
After discussing this benchmarking with the customer, it was decided that the "L" shaped cabinet would be pursued for both the kitchen and the hospitality room. The customer thought that it would be best to have the cabinet be a multi-use cabinet. The "L" concept provides this multi-use by doubling as a bench and extra storage unit. It can further be used as a platform for any services they have. The "live" benchmarking document can be found here.
CabinetsDesigns for the "L" shaped cabinet were produced using Autodesk Fusion 360. Below show the completed designs for this concept.
The interior of the frame and exterior shell are going to be constructed using wood. A cover over the wood would be applied in order to seal any openings to prevent bed bugs. The door is to be connected using a hinge mechanism with the door opening upwards for the bottom section. The bottom section of the cabinet will also double as a couch/resting area so that people can sit or lay down in this area. The seating height for this cabinet is slightly above the average seating height of 18 inches, with about 22 inches. This area could also be used for other needs such as a platform to stand on. The extra space on the end of the cabinet can be used as extra storage as well. This concept is used in both the kitchen and hospitality room, however the designs for both are slightly different as the space provided on the step for each are different. Images of the designs are shown below.
The assembly and component drawings for the hospitality room cabinets can be found here (PDF format). The top-level assembly for the hospitality room cabinet is drawing number P17431-0036 (four sheets total). All other drawings in this directory are component drawings for the hospitality room cabinet.
The assembly and component drawings for the dining room cabinet can be found here (also PDF format). The top-level assembly for the dining room cabinet is drawing number P17431-0053 (three sheets total). All other drawings in this directory are component drawings for the dining room cabinet.
Storage CartsThe cart concept that was approved by the customer is shown below. This concept has four casters, a 2x4 wooden base and steel L bars attachments on the top. The totes are to be placed on the cart six totes high and is meant to have the tote sit on the steel L bars. An image of the cart is shown below.
Image of the storage cart design. The design uses 1.5" steel "L" channel instead of the original 2" channel, because availability of the 2" channel is limited.
The assembly and component drawings for the storage carts can be found here (PDF).
Bill of Materials
CabinetsWith the designs for the cabinet being completed, the bill of the materials was created. As the design for the cabinet in the hospitality room and the kitchen room are different, the bill of materials has two separate lists for each cabinet. The cabinets required 9 unique parts. Some parts are used in both cabinets but are only placed under one list. The cost for the kitchen cabinet came out to be a total of $429.00. The cost for the hospitality room cabinet came out to be a total of $635.34. For both the kitchen and hospitality room cabinets, the highest cost was incurred from the plywood, being about 60% of the total cost. With the cost of both cabinets, it brings our overall expense for cabinets to be $1062.34. The bill of materials for the cabinets is shown below. The "live" Bill of Materials can be found here (note that the bill of materials for the cabinets is on the sheet named 'Cabinets').
Storage CartsA final bill of materials was completed for the cart. The cart only required 5 unique materials to be created, with a cart costing $58.10. With the building and testing completion of the first cart, the team had decided for the remaining carts to change two of casters to be only rigid casters in order to have better control of the cart. The first cart will remain with the four swivel casters as one cart is required to be pushed into the side of the closet. The total cost for all six carts to be build will be $310.07. The bill of materials for the carts is shown below. The "live" Bill of Materials can be found here (note: the bill of materials for the storage cart is on the sheet named 'Storage').
Total Project CostWith the Bill of Materials completed for both the cabinet and the cart, the total cost was calculated to be $1374.41. As our budget is $1500.00, we have very little extra expenses to have and would need to be careful that no mistakes are made during the build and test as purchasing new parts may be out of the scope of our budget. There are some costs that are not included into our bill of materials. These include some kind of cushion or cover for the seating area of the cabinet in the hospitality room. Another cost that is not included is the renovation of the closet (leveling the floor of the closet so that the carts can slide in and out.) If in dire need, the team can request for extra funds in order to complete the carts and cabinets.
FeasibilityFeasibility for the cabinet and the cart were completed to ensure that they can can fit within the constrained space and be able to support any required weight with at least a 1.5 safety factor. (This safety factor was by Professor Faraque)
Space feasibilityA high-level analysis of the floor space requirements of the cabinets was conducted. This rapid analysis showed us that cabinets could fit within the available space on the front step of the hospitality and dining rooms. It also yielded a quick estimate of how much of the windows would be blocked by the cabinets. It was determined that two vertical cabinets, one in each room and each holding ten mattresses, would each require approximately a 44" X 53" footprint. The cabinets are approximately 1/3 of the width of the windows in each room, which should still allow ample natural light into the rooms. The steps (at 48" and 55" wide) are wide enough to accommodate such cabinets. The full analysis can be found here.
Structural FeasibilityThe structural integrity of the cabinet was determined using a stress analysis for the parts of the cabinet, taking into consideration that people would be sitting on top of the structure. Estimating that a person will weigh 400 lbs, the plywood, vertical lumber, and horizontal lumber are able to safely hold a person with a safety factor of 4. The details of the analysis can be found here (Microsoft Word format).
Storage CartsSeveral aspects of the feasibility of the storage carts was analyzed, namely, the space usage of the carts and the volume of storage available to the guests, the weight capacity of the carts, and the ability of the carts to resist tipping.
Space feasibilityIn order to determine whether the cart will fit within the closet, a space utilization was completed. With all the limits of space within the closet, six carts stacked 6 high is able to fit in the closet with at least 1 inch of clearance for the walls and other carts without blocking the fridge vent at the top. This will a total of 36 boxes, allowing 2 boxes for 18 guests. The total amount of personal storage space for each guests is 4.52 cubic ft. The feasibility analysis can be found here (Microsoft Word format).
Weight feasibilityTo determine the weight capacity of the carts, a stress analysis was completed on the cart. Using an average weight of each tote to be 30 pounds, the cart is able hold the total weight of the totes of 180lbs with a safety factor of 2. The analysis document can be found here (Microsoft Word format).
Tipping feasibilityOne area of concern for the team was the possibility of the carts tipping when pushed. The carts have a very short wheelbase compared to the height of the stack of totes on top of them, which may make them prone to tipping. An elementary tipping analysis (based on concepts from dynamics) was conducted, and can be found here. This analysis assumed that the cart wheels are not free to roll, but must slide on the floor. Therefore, they experience friction that can be approximated as Coulombic. This is considered to be a worst-case scenario because the cart will be able to roll. If the casters initially perpendicular to the direction of the push, the resistance to motion should be slightly higher than if the push is in the direction that the casters are aligned, because the casters will have to rotate to align with the push. However, it is expected that this increased resistance will still be lower than the resistance of static Coulomb friction. The analysis found that the cart would slide, rather than tip, for coefficients of static friction less than 0.16. This is a very low value, as typical interfaces usually range between 0.3 and 0.6. Therefore, the results of this analysis are inconclusive and testing will be required to ascertain the cart's resistance to tipping.
Updated Test PlansAs the concept changed from the lift to the cabinets, some of the test plans were required to be updated. There was also an additional test added for the bed bug resistance engineering requirement. The test plans were updated to reflect the changes in the system concept. In particular, the change in the system concept necessitated the following changes:
- Remove all references to the platform lift system. Some plans instructed the tester to raise/lower the lifts at specific points in the test. Obviously, this is no longer possible.
- Remove the test for overhead clearance for mattress storage system, as the requirement addressed by this test is now obsolete.
- Remove the benchmark tests for time to locate a guest's belongings. Due to our increasingly cramped time constraints, the "time to locate a guest's belongings" benchmark test will no longer be run. This test was expected to be very time-consuming, as it required the unpacking and repacking of the closet multiple times.
- Rewrite the cart weight capacity test. The test was written under the impression that the carts would have shelves. Now that the carts have been greatly simplified to little more than a plate on wheels, this test needed to be rewritten.
- Add a test plan to evaluate the cart's safety with respect to tipping. As the carts have a very short wheelbase, they are expected to be prone to tipping. Therefore, a test is required to verify that the carts do not tip too easily.
- Created a new Bed Bug Resistance testing report for the newly added bed bug resistance engineering requirement. There is a chance that guests can bring bed bugs from the outside. As the cabinets will be in the hospitality room to be sat on, the there is a higher chance that the bed bugs can use the cabinet to live. This test is performed in the form of a checklist based on research of bed bug activity and prevention. The Bed Bug Resistance test plan is located here.
The updated test plans can be found in the Test Reports folder. Note that older versions of the test plans are located within the archives in that folder.