DigiKey - Introduction to FreeCAD Part 9: Assembly Tutorial | DigiKey
FreeCAD has introduced a new assembly workbench in version 22, which simplifies the process of creating multi-part assemblies. Previously, users had to rely on third-party workbenches for such tasks. The new workbench, contributed by Onell, a company that develops tools for FreeCAD, is aimed at enterprise users but also benefits the broader FreeCAD community. Although the workbench lacks some advanced features, it is user-friendly and effective for testing mechanical designs. The video demonstrates how to use the workbench to create a scissor lift assembly, highlighting the importance of grounding parts and using joints like revolute and cylindrical joints to simulate movement. The tutorial also addresses common issues, such as ensuring parts are not incorrectly constrained, and provides a challenge to enhance understanding by setting limits on part movement using slider joints. This new feature is particularly useful for complex designs with multiple moving parts, offering a practical solution for testing and refining mechanical assemblies.
Key Points:
- FreeCAD's new assembly workbench allows for easier multi-part assemblies.
- Onell contributes to FreeCAD, enhancing its capabilities for enterprise users.
- The workbench is user-friendly, despite lacking some advanced features.
- Grounding parts and using joints are crucial for simulating movement.
- The workbench is ideal for complex designs with many moving parts.
Details:
1. 🆕 Introducing FreeCAD's Assembly Workbench
- FreeCAD previously lacked built-in multi-part assembly capabilities, necessitating reliance on third-party workbenches for tasks like creating a scissor lift demo.
- The introduction of the new Assembly Workbench directly addresses these limitations, providing native tools for more efficient and integrated assembly processes.
- Onell, a for-profit company, is spearheading the development of the Assembly Workbench and additional tools for FreeCAD, targeting enterprise users and enhancing the software's commercial appeal.
- The workbench aims to streamline product development cycles by offering robust assembly features directly within FreeCAD.
- This strategic enhancement positions FreeCAD as a more competitive option in CAD applications, especially for businesses looking for comprehensive, open-source solutions.
2. 🔗 Simplifying Design with Multi-Part Assemblies
- FreeCAD's new assembly workbench in version 22 and version 1.0 provides a practical tool for designers to create and test multi-part assemblies easily, despite lacking some advanced features.
- The simplicity of the workbench makes it accessible for users who need to focus on testing the functionality of their designs without overwhelming complexity.
- Contributions to FreeCAD's main versions, similar to Ubuntu Pro's contributions to the Linux kernel and Debian distribution, enhance the software's evolution and feature set.
- Using the new workbench can streamline the design process by allowing users to efficiently create and manipulate assemblies, which is crucial for iterative design and testing.
3. 🛠️ Creating Components for the Scissor Lift
- FreeCAD version 22 and later include the assembly workbench by default, featuring version 1.0 release candidate 1.
- Start by creating a new document and select the part design workbench to initiate a new body and sketch on the XY plane.
- For the base arm, use the oval tool and set the length to 100 mm and width to 7.5 mm, ensuring the design is fully constrained.
- Set the inner slot width to 3.5 mm, drawing a circle for the peg with a 3.5 mm diameter, and position the slot 8 mm from the peg hole.
- Pad the design to a thickness of 3 mm to complete the first base component, ensuring precision in measurement and constraint application.
4. 🧩 Assembling the Scissor Lift Structure
- The assembly process begins by creating a new body named 'armor1', which serves as the foundation for the structure.
- A subshape binder is utilized to incorporate reference materials, ensuring the design remains independent of the original base structure.
- Sketches are created on the XY plane using the subshape binder's geometry, allowing parts to remain detached from the original base.
- Dimensions for these sketches are carefully set to match the original design without direct attachment, preserving independence.
- A symmetrical slot is crafted with equalized dimensions to align with the original base's length and width.
- Holes are precisely created to accommodate pegs and a center pin, with dimensions mirroring the original design.
- The structure is padded to a uniform thickness of 3 mm, consistent with other components.
- Using the transform tool, components are moved independently of reference geometry, ensuring no direct attachment to original points.
- Additional arms are cloned and systematically renamed to maintain organization and design consistency.
- Pins are designed as proxies for screws, standardized to a 3 mm diameter and 9 mm length for compatibility with pre-designed holes.
- Final assembly involves positioning all pins and arms, completing the scissor lift structure while ensuring alignment and fit.
5. 🔍 Testing and Fine-Tuning the Assembly
5.1. Creating and Editing Assemblies
5.2. Using Joints for Movement
5.3. Adjusting Joints and Parts
5.4. Finalizing and Testing the Assembly
6. 🎯 Challenge: Enhancing Realism in Simulations
- The task involves modifying an assembly to ensure a pin stops at appropriate positions, addressing FreeCAD's lack of collision detection.
- Use a slider joint to define minimum and maximum movement limits for components, ensuring precise control over their range of motion.
- Slider joints do not work with cylindrical objects in a slot; therefore, create temporary bodies to hold the pin and interact with the slider joint effectively.
- For visual clarity and ease of assembly, make temporary bodies transparent during the simulation phase.
- In physical manufacturing, exclude temporary parts and replace them with standard N3 bolts for final assembly, ensuring the design's practicality.
7. 🔮 Future Directions: Advanced Simulation Techniques
- While full assembly simulations might not be necessary for simple designs, they are essential for complex machines with numerous moving parts to ensure efficiency and reliability.
- Sharing successful simulation outcomes on platforms such as Instagram or LinkedIn with specific hashtags and tagging relevant organizations can enhance visibility and professional networking.
- A demonstration is forthcoming on using finite element analysis (FEA) to simulate stress, heat, and vibration, highlighting the practical benefits of these advanced techniques for engineering designs.