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    CAD for Robotics

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    Introduction to CAD for Robotics

    Before we can build physical robots, we need a digital blueprint. That’s where CAD (Computer-Aided Design) comes in. CAD helps us design and visualize mechanical parts, enclosures, and entire robot bodies before we create them in the real world.

    • What is CAD?

      CAD stands for Computer-Aided Design. It refers to software used to create precise drawings and 3D models of parts, systems, and structures. In robotics, CAD helps us design parts that fit together perfectly and function as intended.

      Why is CAD important in Robotics?

      • It allows you to visualize your robot before building it.
      • You can measure, modify, and share parts easily.
      • Essential for 3D printing and laser cutting workflows.
      • Helps in testing and improving your design through simulation.

      Examples of What You Can Design with CAD:

      • Sensor holders and mounts
      • Robot chassis
      • Gears and linkages
      • Battery compartments or protective enclosures

    • Popular CAD Tools for Beginners

       

      Tool Type Recommended For Platform
      TinkerCAD Web-based, drag-and-drop Absolute beginners, school students Browser (no install)
      Fusion 360 Advanced parametric design Intermediate to advanced users Windows, macOS
      FreeCAD Open-source CAD platform Tech-savvy learners Windows, macOS, Linux

       

      In this course, we will begin with TinkerCAD, a beginner-friendly, free web-based tool ideal for learning the basics of 3D design for robotics. You don’t need to install anything—just a browser and your imagination!

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    TinkerCAD

    Getting Started with TinkerCAD

    TinkerCAD is a free, browser-based 3D design tool by Autodesk. It is ideal for beginners who want to quickly create, modify, and visualize 3D parts. In this section, we will learn how to set up and use TinkerCAD to start designing basic robot components.

    • Step 1: Create a Free Account

      1. Go to tinkercad.com.
      2. Click on Join Now or Sign In.
      3. Create a free account using your email or Google login.

      Step 2: Understanding the Interface

      • Workplane: This is your design surface, similar to a virtual table.
      • Shapes Panel: Pre-made geometric shapes you can drag onto the workplane.
      • Navigation Tools: Orbit, zoom, and pan to move around your model in 3D space.
      • Inspector: Lets you adjust size, color, and settings for each shape.

      Step 3: Your First Design – A Simple Box

      1. Drag a Box shape from the right-side panel to the workplane.
      2. Use the white corner dots to resize it.
      3. Use the black arrows to lift it up or rotate it.
      4. Duplicate the box using Ctrl + D and try combining it with a cylinder or wedge.

      Step 4: Grouping and Aligning Shapes

      • Select multiple shapes using your mouse or Shift key.
      • Click Group (Ctrl + G) to combine them into one part.
      • Use the Align Tool to perfectly center or distribute shapes.

    • Tips for Beginner Designers

      • Keep your designs simple at first – work with basic shapes.
      • Label parts for easy reference.
      • Use colors to indicate different functions (e.g., sensor mounts in red, motor holders in blue).
      • Save your design frequently and use versions to track progress.

      Once you're familiar with the basics, you can start designing robot components like sensor brackets, chassis cutouts, or custom enclosures. In the next section, we'll move on to designing a basic sensor holder step-by-step.

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    A Simple Sensor Holder

    Activity – Design a Simple Sensor Holder

    In this activity, you will design a simple sensor holder in TinkerCAD. Sensor holders are essential parts of a robot as they secure components like ultrasonic sensors, IR sensors, or light detectors. This hands-on section will guide you through creating a basic yet practical holder for an ultrasonic sensor.

    • Step-by-Step Guide

      1. Measure Your Sensor
        For example, an HC-SR04 ultrasonic sensor typically has:
        • Mounting holes distance: ~41 mm
        • Hole diameter: ~3 mm
        • Overall sensor size: ~45 x 20 mm
      2. Create a Mounting Base
        Drag a box shape onto the workplane and set its dimensions to:
        • Width: 50 mm
        • Depth: 30 mm
        • Height: 5 mm
      3. Add Mounting Holes
        Use the cylinder tool to make two holes for the screws:
        • Diameter: 3 mm
        • Height: 6 mm
        • Position them 41 mm apart
        • Change them to 'Hole' and align with the base
      4. Design the Sensor Slot
        Use a box or combine multiple shapes to create a slot or cutout that matches the body of the sensor.
      5. Group the Design
        Select all parts and group them to finalize your sensor holder.

      Sample Dimensions Table

       

      Part Shape Dimensions (mm) Notes
      Base Plate Box 50 x 30 x 5 Main support for the sensor
      Mounting Hole Cylinder (Hole) 3 dia x 6 height Use 2, placed 41 mm apart
      Sensor Slot Custom (Box/Other) 45 x 10 x 15 Space for sensor body

      Tips

      • Use the “hole” feature in TinkerCAD for cutouts and screw spaces.
      • Group parts to avoid accidental movement.
      • Use the ruler tool to place holes accurately.

       

      This activity teaches you precision, alignment, and the importance of mechanical fit. In the next section, we will look at how 3D printing turns this design into a real-world part.

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    3D Printing for Robot Chassis

    Intro to 3D Printing for Robot Chassis

    3D printing allows us to transform digital designs into real, physical components—perfect for robotics where custom parts like chassis, brackets, or mounts are needed. In this section, we will focus on how to prepare and print a basic robot chassis using a 3D printer. Whether you're using an FDM printer at home or accessing one through a makerspace, understanding the process is essential.

    • Why Use 3D Printing for Chassis?

      • Custom fit for motors, sensors, and battery compartments
      • Lightweight and durable designs
      • Low cost for prototyping and experimentation
      • Fast turnaround for iterations and improvements

      Materials Commonly Used

      • PLA (Polylactic Acid): Easy to print, biodegradable, ideal for beginners
      • ABS (Acrylonitrile Butadiene Styrene): Tough and heat-resistant, but requires better temperature control
      • PETG (Polyethylene Terephthalate Glycol): Balance of strength and flexibility, good for stronger parts

    • Key Design Considerations for a Robot Chassis

      • Component Layout: Plan where motors, sensors, and battery packs will go
      • Mounting Holes: Include correct hole sizes and positions for screws or clips
      • Cable Management: Leave slots or tunnels to route wires neatly
      • Accessibility: Make openings for switches, ports, or SD card slots
      • Strength: Use ribs or thicker walls in high-stress areas like motor mounts

      Basic Printing Workflow

      1. Export your 3D design from TinkerCAD or Fusion 360 as an STL file
      2. Import the STL into a slicer software (like Cura or PrusaSlicer)
      3. Choose settings like:
        • Layer height (e.g., 0.2 mm)
        • Infill (e.g., 20% grid)
        • Supports if there are overhangs
      4. Generate G-code and send it to the printer (via SD card or USB)
      5. Start the print and monitor the first few layers to ensure adhesion

      Example Print Settings Table

       

      Setting Recommended Value Explanation
      Layer Height 0.2 mm Balance between detail and speed
      Infill Density 20% Lightweight yet sturdy
      Print Speed 50 mm/s Safe speed for PLA
      Nozzle Temperature 200°C For PLA filament
      Bed Temperature 60°C Helps with bed adhesion

       

    • Tips for a Successful Print

      • Always level the bed before printing
      • Use blue painter's tape or glue stick for better adhesion
      • Watch the first 2–3 layers to avoid shifting or warping
      • If printing in ABS, ensure good ventilation and use an enclosed printer

      3D printing enables you to iterate and customize your robot chassis designs with ease. As your skills grow, you can create increasingly complex and professional parts tailored to your robotics projects.

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    Support Material Principles

    Support Material Principles

    When designing parts for 3D printing, especially for robotics, you may encounter overhangs or complex geometries that cannot be printed in mid-air. This is where support materials come in. In this section, we’ll understand what support structures are, when they are needed, and how to optimize them for clean and successful prints.

    • What Are Support Materials?

      Support materials are temporary structures printed along with your main object. They provide physical support to overhanging parts that would otherwise sag or collapse during printing.

      When Are Supports Required?

      • Overhangs greater than 45°: Anything steeper generally needs support
      • Bridges: Flat horizontal parts between two points (limited span can be done without supports)
      • Floating Elements: Any parts of the model that are suspended mid-air

      Types of Support Structures

      • Grid: Strong and widely used, but harder to remove
      • Lines: Easier to remove but less supportive
      • Tree (Organic): Branch-like supports, useful for minimizing contact with the model

    • Best Practices for Using Supports

      • Design parts with as few overhangs as possible to minimize the need for support
      • Orient the model to reduce unsupported angles
      • Use support blockers in slicer software to exclude unnecessary areas
      • Enable ‘support interface’ layers for cleaner separation
      • Use soluble supports (e.g., PVA) with dual-extruder printers for easier removal

      Example Support Settings Table

       

      Setting Recommended Value Purpose
      Support Overhang Angle 45° Supports enabled beyond this angle
      Support Pattern Lines/Grid Choose based on ease of removal vs. strength
      Support Density 15% Balance of strength and material saving
      Z Distance 0.2 mm Gap between support and model for easy removal

      Removing Supports

      • Use pliers or flush cutters for larger supports
      • Sanding or filing can help smooth leftover marks
      • Use warm water to dissolve PVA supports if used
      • Be gentle—rushing support removal can break delicate parts

      Support materials are essential for printing complex shapes, but with good design practices and slicer settings, you can keep them minimal and manageable. Learning how to work with supports will allow you to design more creative and functional robotic parts.

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    Print Gear Mechanisms

    Activity – Print Gear Mechanisms

    In this hands-on section, you will explore how to design and 3D print simple gear mechanisms. Gears are essential for transmitting motion and torque in robotics. Understanding how they work will allow you to build more efficient and powerful robots.

    • What Are Gears?

      • Gears are rotating machine parts with teeth that mesh with other gear teeth to transmit torque.
      • They help change the direction, speed, or torque of motion.
      • Common gear types: spur, bevel, worm, and planetary gears.

      Why Print Gears?

      • Custom gears allow for precise fit and functionality in robotics projects.
      • 3D printing makes it easy to prototype and test gear systems before finalizing a design.

    • Designing Gears in TinkerCAD

      1. Open TinkerCAD and create a new design.
      2. Use the Shape Generators section and choose Gear.
      3. Adjust the gear properties like number of teeth, pitch diameter, and thickness.
      4. Duplicate gears and align them to create a simple transmission system (e.g., two gears rotating together).

      Tips for Better Gear Printing

      • Use fillets or chamfers on edges to prevent sharp corners.
      • Set a proper clearance between gears so they don’t fuse while printing.
      • Ensure the orientation on the print bed reduces the need for supports.
       

    • Printing and Testing

      1. Export the design as an STL file from TinkerCAD.
      2. Slice the file using Cura or your preferred slicer with appropriate layer height (e.g., 0.2mm) and infill (20%-40%).
      3. Print the gears and test them manually by mounting them on sticks or axles.
      4. Observe rotation smoothness and check for proper tooth meshing.

      What You’ll Learn

      • Basic gear mechanics and applications in robotics.
      • How to use TinkerCAD for mechanical design.
      • Key 3D printing considerations when making small mechanical parts.
      Note: Be patient during gear printing. Even small deviations can affect performance. Measure and refine your design as needed.
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    Cost and Material Considerations

    Cost and Material Considerations

    Understanding the cost and material usage of 3D printed parts is crucial for practical robotics. Whether building one robot or scaling to a classroom project, knowing how to estimate cost and choose the right material helps you stay efficient and budget-conscious.

    • Common 3D Printing Materials

      • PLA (Polylactic Acid): Most common and beginner-friendly, eco-friendly, low warping, ideal for most robot parts.
      • ABS (Acrylonitrile Butadiene Styrene): Stronger and more heat-resistant, but harder to print and prone to warping.
      • PETG (Polyethylene Terephthalate Glycol): Combines ease of printing with good strength and flexibility.

      Material Cost Overview

       

      Material Cost (per kg) Strength Print Difficulty
      PLA ₹800–₹1200 Moderate Easy
      ABS ₹1000–₹1500 High Challenging
      PETG ₹1200–₹1600 High Moderate

      Estimating Print Cost

      1. Most slicer software shows the estimated filament used (in grams).
      2. Example: A sensor holder uses 15 grams of PLA.
      3. If 1kg costs ₹1000, then:
        Cost = (15/1000) × ₹1000 = ₹15
      4. Include electricity and printer wear (approx. ₹2–₹5 per part).
       

    • Design Tips to Reduce Cost

      • Use minimal infill (10–20%) for non-load-bearing parts.
      • Optimize orientation to reduce support material.
      • Combine small parts into one print job to save time.

      Project Budget Planning

      When planning classroom or club robotics projects, create a simple cost sheet for each part and material. Account for:

      • Filament cost per part
      • Number of parts per robot
      • Reprint allowance for failed prints
      Note: Always balance quality and cost. A slightly more expensive material may save you reprint time and breakage in the long run.
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    Chassis and Mounts

    Design for Robotics – Chassis and Mounts

    When designing a robot, the chassis serves as the backbone. It holds everything together — motors, sensors, battery, and microcontroller. A well-thought-out chassis design can make a robot easier to assemble, more robust, and easier to maintain or modify.

    • 1. What Is a Robot Chassis?

      A chassis is the physical frame that houses and supports all mechanical and electronic components. In robotics, chassis design can vary widely depending on the type of robot — wheeled, tracked, walking, or aerial.

      2. Key Design Principles

      • Stability: Ensure the center of gravity is low and well-balanced.
      • Accessibility: Allow easy access to wiring and components for testing or repairs.
      • Strength: Reinforce areas that will carry motors or heavy loads.
      • Compactness: Avoid unnecessary bulk while keeping enough room for all components.

      3. Mounting Motors and Sensors

      Different components require different types of mounts:

      • Motors: Use motor brackets or integrate slots into the chassis. Ensure the axle and wheel have room to spin freely.
      • Sensors: Ultrasonic sensors typically go in front, line sensors below or near wheels, and IR sensors depending on behavior detection.
      • Batteries: Should be centrally placed to balance weight and minimize tilting.

      4. CAD Case Study – Recreating a Line-Following Robot Frame

      Let’s take an example of a 2-wheel line-following robot and design its chassis using TinkerCAD or Fusion 360.

      • Base: Rectangle plate (120mm x 80mm x 3mm)
      • Motor Mount Slots: On either side of the back to mount two BO motors
      • Sensor Slots: At the front, for 3 IR sensors placed about 2cm apart
      • Battery Holder: In the middle, with slots for cable routing
      • Microcontroller Space: On top layer or center space for Arduino Nano or Uno

      5. Exporting and Printing

      Once the design is complete:

      1. Group all shapes in CAD software.
      2. Export as STL file.
      3. Slice in Cura/PrusaSlicer with medium infill and layer height of 0.2mm.
      4. Estimated print time: 1.5–2 hours with PLA
      Note: Keep holes slightly larger than required to accommodate 3D printer tolerances. For screw-based assembly, plan hole diameters accordingly (e.g., 3.2mm for M3 screws).
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    Summary and Quiz

     

    You’ve now gained foundational knowledge in CAD and 3D printing tailored for robotics. From understanding CAD tools like TinkerCAD and Fusion 360 to designing simple mounts and full chassis, you’ve explored how digital design converts into tangible parts. You also learned about printer settings, slicing, support materials, and cost estimation. It’s time to test your learning and take the next step in turning ideas into reality through design. Let’s begin the quiz!