A learning center needs a proper station for sensory exposition for children that is able to accommodate 4 children at once with room for an adult to access each child.
The learning center’s current system involves 4 individual elevated bins with the sensory content with clamps to hold on the lids. While this is relatively functional, there is also an issue of the lids on these bins not being childproof. The center coordinators also asked for this station to have some form of entertainment when the sensory bins are locked and also for the station table to have some form of storage. The station will need to be mobile and have the ability to roll around but also remain in place when needed.
Table Top:
Storage Legs:
Wheels:
Bins:
Lids:
For our background research, we explored key components needed to design a safe and functional sensory station. We compared different caster options and their effects on mobility and stability with an emphasis on a locking mechanism. We also reviewed childproofing methods for the bin lids while weighing their durability and safety. To meet the learning center’s request for entertainment features, we examined sensory options for the lids so they could be detached and used independently from the table. These insights are what have guided our decision making while designing our safe, interactive, and modular sensory table for kids.
Design with 4 legs, wheels, and a large central storage section.
Design with 4 legs and storage built in to the legs
Design with 8 legs and drawers in between.
Our portable storage center is equipped with four stations, each housing a storage container that can hold sensory toys, materials, and other necessary items. The lids for each bin are busy boards with an assortment of different toys and activities such as finger painting, Lego building, sliding puzzles, and more. There are 8 different busy board designs in total, each with unique activities. The lids for each bin will contain a simple padlock locking system to ensure that the children cannot access the inside of the bins without supervision. The table is approximately 18-20 inches tall and is easily portable as the bottom of each table leg includes castor wheels with built-in locking systems to prevent it from sliding across the carpet. The central storage area will be used for instructor/guardian access and can house any additional items they need.
In the following calculations, we performed a static analysis of the table in four parts (A–D).
Part A:
We began by calculating the mass of the table. Using the given dimensions, we first determined its volume and then estimated the mass based on the density of Northern Red Oak—a common wood species in the U.S. According to ETT Fine Woods (https://ettfinewoods.com/species/red-oak/), the table’s estimated mass is approximately 216.9 lbs.
Part B:
Next, we used basic static principles to calculate the forces acting on the legs when the table is unloaded. The total downward force due to the table’s own weight was found to be approximately 1,750 lbf distributed across the legs.
Part C:
We then determined the maximum load required to cause structural failure of the legs. Using the maximum normal stress for Northern Red Oak from WoodBin’s strength table (https://woodbin.com/ref/wood-strength-table/), and assuming each leg has a radius of 1.5 inches, we calculated that each leg can withstand up to 47,783.6 lbf. This is far greater than the static load from Part B, indicating that the table can safely support significant additional weight without risk of leg failure.
Part D:
Finally, we analyzed the table’s stability to see whether it could tip over if a child sat or applied weight on its edge. Using a child weight chart (https://sprintmedical.in/blog/weight-and-growth-chart-for-kids), we found that for the table to tip, it would need to weigh less than 23 lbs. Since the table’s mass (216.9 lbs) is much greater than this, it would remain stable even if a child—or likely an adult—leaned or sat on the edge.
Materials Analysis
In this analysis, we will look at materials used for table design to determine their suitability based on mechanical performance, durability, and practicality. Northern Red Oak is a widely available hardwood commonly used for furniture and interior construction due to its strength, workability, and aesthetic qualities.
Part A
Northen Red Oak has well-documented mechanical and physical properties that make it an ideal material for furniture. The relevant data is summarized in the corresponding table.
These Values indicate that Northern Red Oak is highly stiff and can withstand significant compressive and bending stresses which make it well suited for applications such as table legs and tabletops.
Part B – Suitability for Table Design
Based on our static analysis, the maximum load experienced by each table leg is about 1,750 lbf, while the calculated failure load given by normal stress is 47,783.6 lbf. Considering both these values we end up with a safety factor which is approximately 27, which shows that Northern Red Oak is more than strong enough to withstand expected loads.
Additionally, Red Oak’s high modulus of elasticity means it will resist deformation under normal use which will prevent sagging at the center of gravity over the course of time. The moderate density also means that the table will remain stable but now excessively heavy for practical uses.
Part C – Comparisons with Alternative Materials
To test the Validity of our choice material we compared it with other common furniture materials such as Pine, Maple, and MDF (Medium Density Fiberboard) as seen in the corresponding table. Data was pulled from these sources: 1. https://www.wood-database.com/eastern-white-pine/ 2. https://www.wood-database.com/hard-maple/ 3. https://www.makeitfrom.com/material-properties/Medium-Density-Fiberboard-MDF
While Pine offers cost and weight advantages, it is significantly weaker. Maple provides similar strength, but it is more expensive and harder to machine. MDF, while inexpensive and stable, lacks the strength and appeal of solid wood. Therefore, Northern Red Oak proved the best balance of all the desirable properties.
Part D – Conclusion
Based on its mechanical performance, safety factor, and other advantages, Northern Red Oak is a good choice for table construction. It provides sufficient strength to handle loads well beyond expected use, resists deformation, and maintains an aesthetic appearance for the classroom.
For fabrication we began with machining the table top, cutting it to size and shape, then machining the holes needed to accommodate the bins, sensory boards, and center storage. We bounced between cutting and assembling, but for cohesion, the processes will be described separately. We cut all the rest of our wood for the busy boards, cross bracing, lattice support, and brackets to hold bins. Our first assembling step was the brackets, which we both glued and screwed into place, then the lattice support was attached, followed by the center storage bin being assembled and attached (almost everything was glued and screwed in). The process has yet to be finished, but the remaining steps are to attach the cross bracing to the legs, attach the legs, wet sand all surfaces, and seal everything with polyurethane. The last step will be attaching the various elements of the busy boards and the magnetic locks to childproof unauthorized access to the bins underneath.
To test our project we did various things as there were many elements to test. To ensure the table was sturdy and secure, one member sat on the tabletop near an edge to ensure it could hold weight, resist tipping, and resist any other type of failure. For the busy boards, as each element was attached, the element was tested for functionality and attempts at removal. Our table was also on retractable casters so we tested those for their ability to retract and extend and roll. Lastly, each busy board was affixed to a magnetic locking system that ensures busy boards cannot be removed without an adult, we had to test an make sure the locks fit in and were functional.
In summary, we built almost exactly what we imagined this table would look like with the only deviation from our selected designs was to add bracing to ensure the sturdiness of the table. A major part of our success and the satisfaction of the recipient was the quality of communication that each team member upheld and the communication of our client. We were given clear, reasonable, and well explained details upon which we could design and fabricate the table. To be quite honest, a significant part of the design was already done for us, provided in a packet of illustrations and notes. Our task was to make sure the design was structurally safe and possible to fabricate. The fabrication part of this project provided each member with a number of learning experiences, be it how to operate a tool in the shop, what elements need to be considered before assembling something, or how to fix a mistake. It was a rewarding process that ended in success and satisfaction for each member and our customer.
