Table of Contents
Design 1 Summary
The Deckloo is constructed from plastic lumber boards made from 100% recycled HDPE. The design has thinner sections of HDPE which lay next to each other to form the top surface to stand on. This is supported by several thicker cross-member sections of HDPE under the top surface that run perpendicular to the top boards. The inspiration for the design was based on the standard design layout for most common household decks and patios. The design is slightly inset into the ground to provide stability and prevent movement while in use. Also, there is an additional piece of HDPE to cover the opening to the hole below while the device is not in use. The entire device weighs 17.4lbs when assembled and is designed to support 270lbs.
Design 1 Assembly
The Deckloo was made from 100% recycled HDPE plastic lumber. This material is often used as an alternative to pressure treated lumber and is excellent in outdoor applications. HDPE’s resistance to environmental stress cracking makes it ideal for outdoor structural use, satisfying ER S13. Because the Deckloo is made from 100% recycled material, it’s impact on the environment is greatly reduced, meeting ER S14. The structural support comes from seven rows of 1.5 inch by 1.5 inch runners that span the width of the Deckloo. Supports are spaced at 5.75 inches apart to ensure that the stress is distributed properly and that the deflection between the supports is not too high. The total deflection under the loading condition of 270lbs in a single location was found to be approximately 0.44 inches. This was validated during load testing when the maximum deflection was found to be 0.45 inches under a load of 572 lbs, distributed across two locations; fulfilling ER S2. The runners are attached to the top platform with standard deck screws. The top platform is made of 0.25 inch thick by 10.25 inch wide sheets cut in 36 inch lengths. The sheets are cut so that an 8 inch by 10.25 inch rectangular gap can be used as the squat hole. Leftover 0.25 inch sheet strips are used to cover the side gaps left by the runners, and a lid is fashioned from extra 0.25 inch sheet. The completed design weighs 17.4lbs, meeting ER S9 and ER S10 and can be seen above.
Design 1 DocumentsDesign 1 Drawing Package Rev 2
Design 1 Mold Rev 4
The final revision of the mold, shown below, was created using a 22 inch by 22 inch block of maple laminated wood. The mold was CNC machined at an outside company to form a single component. The mold featured the same rib structure that was used revision two. The base thickness for the rib features were increased to 0.80 inches. The increase in thickness was necessary to create a 0.125 inch clearance for the rebar. The overall height of the outer rib pieces was decreased to 1.0625 inches and the inner rib pieces height was reduced to 0.5625 inches. The reduction in height was to accommodate the switch over from using quarter inch HDPE to sixteenth inch plastic. The reduction in height was to maintain a half inch difference between inner and outer rib features. Two wood blocks were removed from the mold and replaced with eight additional rib features. The rib features were less complicated to machine and vacuum form, and provided improved strength and stability compared to wooden tabs. The four corner wood blocks were retained to provide features to support the cover. The additional rib features had a base thickness of 0.65 inches. Draft angles for outer tabs were increased to fifteen degrees. The increased draft angles allowed for improved removal of the mold from a formed base. All other draft angles were increased to seven degrees to improve mold extraction and to allow for standardized tooling for machining the mold.
Design 1 Mold Rev 4 DocumentsDesign 1 Mold Drawing Package Rev 4
The test for Engineering Requirement S2, load supported, used a custom set of loading fixtures to simulate a person standing on the bases and followed ASTM E455. For each base there was a fixture to simulate the ground during the test, and there was a second fixture that held standardized gym free-weights which had two posts underneath to simulate the feet of a person standing on the base. Gravity Load Test
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Test Set up
Test Fixture Documents
In order to improve processing times, assembly fixtures were created. The rebar support frames for the Vacloo required two fixtures, which required welding; therefore, they were made of steel. A 3/16 inch steel plate and 1/8 inch by 1.5 inch by 1.5 inch angle iron was used for the base and stops for each of the Vacloo assemblies. The stops were welded to the base plate. Process times are improved by clamping rebar to the stops and tack welding to avoid having to measure and square for each assembly produced.