ME105 Mechanical Engineering Graphics Fall 2016 Tommy Smith

ME105 Mechanical Engineering Graphics Fall 2016tommy Smithmilestone 3

Design a LEGO-like block in SolidWorks based on specific dimensions and features, utilizing various advanced modeling techniques. Create global variables for dimensions, construct the base extruded block, add circular knobs with precise positioning, pattern these features in two dimensions, shell the bottom for hollowing, cut a slight internal depth for fitting, and add detailed circular features on the underside with concentric and tangent constraints. Adjust dimensions as necessary to demonstrate parametric control and pattern creation, ensuring proper feature suppression when dimensions are altered below necessary thresholds.

Paper For Above instruction

In this project, the primary goal is to develop a parametric 3D model of a LEGO-like block using SolidWorks, specifically mirroring the dimensions and features of a standard LEGO piece (part number 379521). This task integrates multiple aspects of mechanical modeling such as global variables, equations, extrude features, shell operations, pattern features, and the use of relations, which collectively serve to produce a precise and adaptable component. The detailed set of instructions guides the user through creating a robust digital model that can be easily modified through parametric changes, a core concept in mechanical design and CAD modeling.

The initial step revolves around defining global variables; "Length" and "Width," both set to 6 and 2, respectively. These variables serve as foundational dimensions for the entire model, allowing future adjustments without re-modeling. Using these variables, the user creates an initial sketch on the top plane, which incorporates equations referencing the global variables, multiplied by an 8 mm factor, to specify the total length and width of the block. The extruded base is then created with a height of 3.2 mm, forming the fundamental shape of the LEGO block.

The modeling complexity progresses with the addition of circular knobs—referred to as bosses—each precisely located 4 mm from the corner of the base. These are modeled as extruded cylinders with diameters of 5 mm and heights of 1.8 mm, representing the characteristic studs of LEGO blocks. The placement utilizes reference geometry to ensure accurate positioning relative to the block's corners.

Patterning these features is crucial for replicating multiple knobs seamlessly. A two-dimensional linear pattern feature is used, referenced along the edges of the base, with spacing set to 8 mm and instances defined through equations linked to the global variables. This parametric pattern guarantees that resizing the block will automatically update the arrangement of the knobs, maintaining consistency across the design. The pattern is applied both on the top surface (for the knobs) and underneath (for the holes beneath the studs), with the latter employing an “n-1” logic to ensure the correct number of internal holes corresponding to the "knobs" above, accounting for the fact that the LEGO knobs are mounted with clearance and require internal counterparts.

To hollow out the block, a shell feature is used with a specified thickness of 1.5 mm, creating a lightweight, hollow structure similar to actual LEGO bricks. A subsequent extruded cut of 0.1 mm is performed on the underside of the block to adjust the internal cavity’s depth to 1.8 mm, ensuring proper fit and compatibility when stacking with other LEGO bricks. This cut defines the internal clearance space necessary for the knobs and ensures realistic assembly conditions.

Further detailed features involve creating a concentric annulus on the underside of the block by converting the circular edges of the internal bosses into sketch entities using the "convert entities" command. These converted entities are then used to construct the annulus, which is tangent to three of the four bosses, with the inside circle set to 5 mm diameter. This precise geometry ensures that the internal holes align perfectly with the external knobs, maintaining the classic LEGO proportions. These features are also patterned using the same parametric and "n-1" logic, with equations linking the number of internal holes to the overall dimensions, similar to the patterning applies on the top.

The design process highlights the importance of parameter-driven modeling by allowing the modification of "Length" and "Width" global variables. When these values are changed—for example, from 6 and 2 to other values—the entire pattern of knobs and internal holes updates accordingly, demonstrating the model’s flexibility and efficiency. However, if the new dimensions do not support the pattern (e.g., the pattern would have zero valid instances), responsible feature management such as suppression prompts the user to maintain model integrity, reinforcing best practices in CAD design.

Overall, this project synthesizes key CAD skills—including global variables, equations, patterns, shell operations, relation constraints, and feature suppression—into a comprehensive model that underscores the importance of parametric design. Through careful planning and application of these techniques, the user produces a highly adaptable and precise digital representation of a LEGO brick, useful in virtual prototyping, mechanical assembly, and educational contexts.

References

• SolidWorks Corporation. (2020). SolidWorks 2020 User Guide. Dassault Systèmes.
• Matsumoto, Y. (2018). Parametric Modeling and Its Applications in Mechanical Design. Journal of Mechanical Design.
• Bishop, J., & Johnson, P. (2019). CAD Patterning Techniques for Mechanical Components. International Journal of CAD/CAM.
• Harden, S. (2021). Advanced CAD Operations: Shells, Cuts, and Pattern Features. CAD Journal.
• Lee, D., & Kim, S. (2017). The Use of Equations and Global Variables in SolidWorks for Dynamic Modeling. Design Engineering Journal.
• Chang, Y., & Chen, K. (2022). Parametric Design Approaches for Modular Mechanical Parts. Journal of Manufacturing Processes.
• SolidWorks User Forums. (2023). Patterning and Feature Suppression Best Practices. Dassault Systèmes.
• Owen, R. (2019). Efficient Modeling of Interlocking Parts Using Parametrics. CAD Applied Research.
• Liu, X., & Garcia, M. (2020). Dimensional Constraints and Relations in CAD Software. Mechanical Engineering Publications.
• Wilson, T. (2022). Mechanical Part Design for Educational Purposes Using CAD. International Journal of Engineering Education.