Mastering Screw Sizes In Fusion 360: A Comprehensive Guide

Fusion 360 is a powerful tool that allows users to easily add screw sizes to their designs. By using the Thread command under the Create menu, users can specify the type, size, class, and direction of the thread. This is particularly useful for creating threaded fasteners for screws, nuts, and bolts. The software also offers several preset thread types based on industry and global standards, ensuring that your designs are accurate and reliable. With Fusion 360, you can create realistic and working threads for your projects, which can be 3D printed, milled, or used in 2D manufacturing drawings.

Converting decal threads to 3D models

Fusion 360 is a powerful tool that enables users to create realistic and working threads for their projects. These threads can be easily converted from 2D decals to 3D models, making them suitable for 3D printing, milling, or manufacturing drawings. Here is a step-by-step guide on converting decal threads to 3D models in Fusion 360:

Step 1: Understanding Thread Types

Fusion 360 offers a variety of preset thread types, including ACME Screw Threads, ANSI Metric M Profile, ISO Metric Profile, and more. These thread types adhere to industry and global standards, ensuring that your threads are accurate and compatible with other components. When selecting a thread type, consider the specific requirements of your project.

Step 2: Creating the Thread

To create a thread in Fusion 360, start by selecting the "Thread" command from the "Create" menu. Choose the circular face where you want to apply the thread, specifying whether it is internal or external. Fusion 360 will then suggest the closest standard thread size based on your selection.

Step 3: Adjusting Thread Settings

You can further customize your thread by specifying the thread type, such as Pipe Threads, ACME Threads, or Metric Threads. Additionally, you can modify the thread size, thread length, and thread direction (right-hand or left-hand). These options provide flexibility in designing threads that meet your specific needs.

Step 4: Converting to 3D Modelled Threads

By default, Fusion 360 displays threads as decals to improve performance and reduce processing power. However, if you need 3D modelled threads for 3D printing or other purposes, you must convert them. To do this, go to the Document Settings in the Browser and change the Threads option from "Cosmetic" to "Modelled." This simple step will transform your decal threads into 3D models that can be used for various applications.

Step 5: Creating Clearance for 3D Printing

When preparing threads for 3D printing, it is crucial to consider clearance. Fusion 360 automatically adds a small clearance of 0.1mm, but this is often insufficient for 3D printing. To create additional clearance, use the Offset Face command. Select the top or bottom flank of the thread, activate the Offset Face command with the "Q" keyboard shortcut, and input your desired clearance value (typically between -0.15 and -0.2 for 3D printing). Repeat this process for the opposite flank and the mated part, such as a nut for a bolt.

By following these steps, you can effectively convert decal threads to 3D models in Fusion 360, unlocking the potential for 3D printing, milling, or manufacturing drawings. Remember to consider thread types, adjust settings accordingly, and create sufficient clearance for a successful 3D printing experience.

Creating custom threads

Fusion 360 has a thread feature that allows users to create realistic and working threads for their projects. These threads can be 3D printed, milled, or used in 2D manufacturing drawings.

To create a custom thread, start by creating a new component. This will allow you to create copies of the design for testing different clearances. Use the cylinder command to create a cylinder with the desired diameter and length for your thread.

Activate the thread command from the "Create" dropdown menu and select the face of the cylinder as the location for the threads. Fusion 360 will automatically detect the size of your cylinder and suggest the closest thread type. To create custom threads, you will need to define the thread size and pitch.

The "Size" option allows you to change the size of the thread. For example, if you switch the size from 16mm to 20mm, the designation will change from m16 to m20.

The "Designation" option lets you define the pitch of the thread, which is the distance from one crest to the next. For instance, if the designation is m16x2, the pitch is set to 2mm. You can adjust the pitch by changing the designation.

Additionally, you can use the Offset Face command to create additional clearance for your thread. Select the top or bottom flank of the thread and press "Q" to activate the Offset Face command. Enter the new clearance value, typically between -0.15 and -0.2 for 3D prints. Repeat these steps for the opposite flank and the mated part, such as a nut for a bolt.

By default, Fusion 360 threads are cosmetic, meaning they are simply decals wrapped around a cylinder. To make the threads 3D printable, check the "Modelled" checkbox at the top of the Thread dialog.

You can also change the thread direction between right-hand and left-hand. Right-hand threads are turned clockwise, while left-hand threads advance when turned counter-clockwise. Most screws use right-hand threads, unless the rotation of the object would gradually loosen with torque, such as bicycle pedals or gas line parts.

Thread milling strategies

Thread milling is a process that involves using a milling machine to cut threads into a workpiece, and there are several strategies you can employ to achieve this. Here are some thread milling strategies to consider when adding screw sizes in Fusion 360:

Selecting the Right Tool

Choose a suitable milling machine for the job. For example, the Bantam Tools Milling Machines do not support rigid tapping, but they can still be used for thread milling. Select a machine that aligns with your specific requirements.

Understanding Thread Pitch and Diameter

When programming a thread milling operation in Fusion 360, you need to know two critical values: the thread pitch and the pitch diameter offset. The thread pitch of a screw is readily available from the fastener you're using. However, calculating the pitch diameter offset is more complex. It involves finding the difference between the major diameter (D) and minor diameter (d) of the machine screw. The pitch diameter offset ensures precision in your threading operation.

Using a Pitch Diameter Offset Calculator

To simplify the process of calculating the pitch diameter offset, you can use a specialised calculator, such as the one created by John Saunders from NYC CNC. This calculator considers the geometry of your tool and provides an accurate pitch diameter offset value. Using this calculator saves time and ensures accuracy in your thread milling process.

Creating Threads in Autodesk Fusion

To create threads in Autodesk Fusion, follow these steps:

• Open the "Thread" command under the Create option in the toolbar.
• Select the face you want to thread, choosing between internal and external threads.
• Check the "Modelled" option to create physical threads instead of a visual representation.
• Customise your threads by adjusting the length, offset, thread type, size, designation, class, and direction.
• Remember to refer to video tutorials and support guides if you need further clarification during this process.

Adjusting Thread Fit

If you encounter issues with the thread pitch being too tight, you can adjust the offset number incrementally (in thousandths of an inch) until your threads fit perfectly. This fine-tuning process ensures that your screw threads smoothly without being too loose or too tight.

By following these thread milling strategies, you can effectively add screw sizes in Fusion 360 and achieve precise and functional threads for your projects.

Calculating pitch diameter offset

When designing screw threads in Fusion 360, it is important to understand the different diameters involved, including the pitch diameter. The pitch diameter is one of the essential dimensions of threaded fasteners, along with the major and minor diameters. The major diameter is the diameter determined by the thread tips, while the minor diameter is the diameter determined by the groove of the thread.

The pitch of a screw thread refers to the distance from the crest of one thread to the next, typically measured in millimetres. The pitch diameter is the distance between two opposite flanks or the centre line of the profile. In the case of 60-degree threads under ISO Metric Standards, the pitch diameter can be calculated using the following formula:

Basic pitch diameter formula:

`d2 = d - (3 × 3^0.5 × P/8)`

Where:

• `d2` is the basic pitch diameter
• `d` is the basic major diameter
• `P` is the thread pitch

For example, let's say we have an M30x2-6h bolt with a 30 mm basic major diameter and a 2 mm thread pitch. We can calculate the basic pitch diameter as follows:

`d2 = 30 mm - (3 × 3^0.5 × 2 mm/8) = 28.701 mm`

To find the maximum and minimum pitch diameter values, we need to consider the fundamental deviations and tolerances. These are the allowances applied to the threads to ensure proper fitting when threaded together. The formulas for external and internal thread pitch diameters are as follows:

External thread pitch diameter formulas:

`d2max = d2 + es`

`d2min = d2 + es - Td2`

Internal thread pitch diameter formulas:

`D2max = D2 + EI + TD2`

`D2min = D2 + EI`

Where:

• `d2max` and `d2min` are the maximum and minimum external thread pitch diameters, respectively
• `D2max` and `D2min` are the maximum and minimum internal thread pitch diameters, respectively
• `es` and `EI` are the fundamental deviations, upper and lower deviations, respectively
• `Td2` and `TD2` are the thread pitch diameter tolerances for external and internal threads, respectively

By applying these formulas, we can determine the specific pitch diameter offset required for a given screw thread design in Fusion 360, ensuring proper fitting and functionality.

Using the thread tool to model threads

To use the thread tool to model threads in Fusion 360, follow these steps:

Creating External Threads:

• Open the thread command under the "Create" option in the toolbar.
• Select the face you would like to thread.
• Check the "Modeled" option to create physical threads instead of a visual representation. This is crucial if you plan to 3D print the threads.
• (Optional) Customize your threads:

• Full length: Uncheck to customize the thread length and offset.
• Thread type: Choose from a range of preset thread types, including ACME Screw Threads, ISO Metric Profile, and more. Fusion will suggest a type based on your model.
• Size: Change the thread size to a different manufacturable option; the model will update accordingly.
• Designation: Define the pitch of the thread, which is the distance from one crest to the next.
• Class: Choose the tolerance class, which determines how tight or loose the fit is.
• Direction: Change the direction of threading from right to left-hand. Right-hand threads are turned clockwise, while left-hand threads advance when turned counter-clockwise.

(Optional) Check "Remember size" to apply these settings to future threads.

Creating Internal Threads:

There are two ways to create internal threads:

Option 1: Tapped Hole

• Create a hole using the "Hole" command or the "h" shortcut.
• Select a face to place the hole and position it using edges or sketch points.
• Select "Tapped" under "Hole Tap Type."
• (Optional) Customize your shape settings:

• Hole type: Choose between Simple, Counterbore, or Countersink.
• Hole tap type: Choose from Simple, Clearance, Tapped, or Taper Tapped.
• Thread offset: Set the distance you want the thread to cover.
• Drill point: Opt for a flat or angled drill point and adjust the dimensions.

Option 2: Add Threading to a Pre-Existing Hole

Follow the same steps as creating external threads, but select an interior face.

Frequently asked questions