how to 3d print gears to make a figure eight​

3D printing transformed the way that we design and manufacture functional mechanical components, as well as prototype. Maybe the most fascinating thing about 3D printing is that we are able to design and print complex parts like gears. Here we are going to walk you through 3D printing gears for creating a figure-eight mechanism. Regardless if you are a hobbyist or an engineer, it is imperative to know how to design and print gears to a variety of engineering and mechanical applications. Use this guide with step-by-step instructions to find out how to print and set up gears that work together to produce a figure-eight motion.

What is a Figure-Eight Gear Mechanism? :

A figure-eight mechanism is a fascinating design in which two gears move in a specific way to create a figure-eight path. This type of mechanism is commonly used in mechanical linkages and is used in numerous applications, from simple models for educational purposes to complex machinery. The principle behind this mechanism is that the gears mesh in a way that their combined motion provides a smooth, continuous figure-eight motion.

Benefits of 3D Printing Gears :

• Accuracy: 3D printing provides high accuracy in designing gears so that each tooth and part fits well into the other.
• Customization: You can customize the size, number of teeth, and shape of gears as per your needs.
• Faster Prototyping: 3D printing speeds up the process of prototyping, and it becomes easier to test and prototype gear designs.

Applications of Figure-Eight Gear Mechanisms :

• Robotics: Used in robot arms or mechanisms that must be very accurately moving.
• Mechanical Devices: Used in models, simulations, and mechanical toys.
• Educational Tools: Ideal to show the mechanics of gear systems and mechanical movement.

Step 1: Designing Your Gears for 3D Printing :

You won’t be able to start 3D printing until you design the gears. You’ll need to determine what kind of gears to use, design their teeth, and order the figure-eight arrangement.

Choosing the Right Gear Type :

There are different types of gears, and choosing the right one is essential in order to ensure proper operation. The two most common types of gears used in a figure-eight mechanism are:

• Spur Gears: They are the most basic and common type of gear. They consist of straight teeth parallel to the axis of rotation. Spur gears are well-suited to figure-eight designs as they are easy and straightforward to design.
• Helical Gears: Helical gears are toothed gears that are slanted rather than straight, so they are quieter and smoother-running. While harder to create, helical gears are a possibility if you need more torque or smoother operation.

Designing Gear Teeth :

When ensuring your gears mesh into one another smoothly, your teeth need to be designed with proper space and pitch. The two most important things to design into gear teeth are:

• Pitch: The space between the teeth. In 3D printing, a standard pitch value is 1.0mm, but it can change depending on the needs of your project.
• Pressure Angle: The angle of contact between the teeth. A standard pressure angle for most 3D printed gears is 20 degrees, but it may differ for different types of gears and applications.
• Tooth Profile: You’ll need to design a tooth profile that meshes well with another gear. The standard involute profile is commonly used.

Creating the Figure-Eight Motion :

The key to creating a figure-eight motion is positioning your gears correctly. You will have two gears that rotate opposite directions in an interlocking setup. To achieve the figure-eight, ensure your gears are positioned at the correct angles and distances from one another to allow for smooth, repeatable motion. Use a 3D modeling software like Tinkercad, Fusion 360, or SolidWorks to accurately position your gears.

• Gear Size: Start with one large gear and one small gear. The size of the gears will decide the speed and torque of the mechanism.
• Angle of Engagement: The gears need to engage at specific points along the figure-eight path in order to have continuous motion.

Software Tools for Gear Design :

Several free and paid tools are available for designing gears for 3D printing:

• Fusion 360: Offers a gear generator plugin that simplifies the process of creating various types of gears with custom parameters.
• Tinkercad: Simple, user-friendly tool for novices with basic design functionality, suitable for creating simple spur gears.
• FreeCAD: Open-source CAD software with extensive features that has an inbuilt gear module for designing different types of gears.

Step 2: Selecting Materials for 3D Printing Gears :

Picking the correct material for your gears is vital for making them durable and high-performing. Each material has its own set of properties, and the correct choice will be based on your particular requirements.

Common 3D Printing Materials for Gears :

• PLA (Polylactic Acid): Great for beginner 3D prints. PLA is simple to use but might not be strong enough for high-torque uses.
• ABS (Acrylonitrile Butadiene Styrene): More durable than PLA and heat-resistant, so a great choice for gears that will undergo wear and tear.
• PETG (Polyethylene Terephthalate Glycol): Durable and flexible, less brittle than PLA, and a good choice for gears.
• Nylon: Durable and flexible, so a good choice for gears that will undergo more load.

Material Properties to Consider :

• Strength and Durability: Gears need to withstand stress and friction, so choose a strong and durable material.
• Friction Resistance: Choose materials with low friction for smooth operation.
• Ease of Printing: Choose a material compatible with your 3D printer’s ability, especially if you are a beginner in 3D printing.

Step 3: 3D Printing the Gears :

Now that you’ve designed your gears and chosen the right material, it’s time to print them. The following are the steps to follow for a successful 3D printing process.

Setting Up Your 3D Printer :

• Printer Type: FDM (Fused Deposition Modeling) printers are usually the best option when printing gears, but SLA (Stereolithography) printers can be used for high detail, precise prints.
• Layer Height: Print with a layer height of 0.2mm for regular prints or 0.1mm for higher accuracy.
• Print Speed: Reduce the print speed for small gears for higher accuracy and quality.
• Infill Density: Print gears with a high infill density (50-75%) so that they are sturdy enough to hold movement.

Printing Tips :

• Support Structures: Depending on the design, you may need to use support structures to prevent warping or sagging during the print.
• Orientation: Print the gears flat on the print bed to prevent warping and to get a smooth finish.
• Post-Processing: You may need to clean up the gears after printing, removing support structures and sanding where necessary.

Step 4: Assembling the Figure-Eight Mechanism :

After printing your gears, it’s time to assemble them into the figure-eight mechanism. Here are some key points to keep in mind when assembling your gears:

Assembling the Gears :

• Aligning the Gears: Carefully align the gears to ensure that their teeth mesh correctly.
• Rotation and Testing: Test the gears by manually rotating them to check for smooth motion. Adjust their alignment if necessary.

Fine-Tuning :

• Adjusting Tension: If the gears are too loose or tight, move them to a position where they have proper tension.
• Lubrication: The use of a small quantity of lubricant reduces friction and improves the life of the gears.

Step 5: Troubleshooting and Optimizing Your Figure-Eight Mechanism :

Despite following these steps, some common problems tend to occur with 3D printed gears. Here are a few troubleshooting techniques:

Common Issues and Solutions :

• Gear Slipping: If your gears are slipping instead of meshing, either adjust their positioning or reprint them with precise measurements.
• Excessive Wear: In case of excessive wear on the gears, try using a stronger material such as ABS or nylon.
• Uneven Rotation: This might be due to misalignment. Re-check the alignment and make sure the gears are free from obstruction.

Conclusion :

A figure-eight mechanism with 3D printed gears is a delightful project where design and engineering efforts are combined. By completing the instructions in this guide, you will be able to create, print, and construct your gears into a fully functional figure-eight system. From beginner to experienced 3D printing enthusiast, this project offers practice in gear design, material selection, and 3D printing process that is priceless. Enjoy, and make sure to experiment with various gear configurations to see the infinite possibilities 3D printing offers.

FAQs : how to 3d print gears to make a figure eight​