T-Nut/Tee Nut
Tee nuts are off-the-shelf metal components that provide a way to add robust threads to a 3D printed part. Tee nuts are generally designed for use in wood and are intended to be hammered in from the opposite side of where the bolt or machine screw attaches.
A ¼-20 UNC tee nut is used to add threads to a project, typically for mounting purposes.
This is one of the most complicated parts to add to a model, with a long list of dimensions required to make a suitable mounting feature. They can come in 3-, 4-, and 6- toothed versions, so the mounting hole has 12 slots to accommodate any version.
Example Files
An example of the part dimensioned below is provided as an STL, a STEP, and a F3D file. Currently only the positive is provided, i.e. the part that was dimensioned, but there are plans to add a negative to allow the component to be imported into a design then added as a Boolean subtraction or addition, depending on if you are using the positive or negative.
Dimensions
The following are the list of dimensions used in the T-Nut mounting feature.
- Counterbore Radius: The radius of the counterbore that sinks the flat surface of the T-Nut that the teeth and threaded shaft come out of.
- Counterbore Depth: The depth of the counterbore that sinks the flat surface of the T-Nut that the teeth and threaded shaft come out of.
- Thread Radius: The radius of the hole through the part that the threaded section of the T-Nut goes through.
- Thread Depth: The depth of the hole through the part that the threaded section of the T-Nut goes through.
- Wall Thickness: The thickness of the outer wall of the T-Nut fixture.
- Chamfer Length: The length of chamfer used to start the hole for the threaded shaft.
- Tooth Spacing: The distance between the centerline of the fixture and the furthest point of the tooth hole.
- Tooth Width: The width of the hole used to capture the teeth of the T-Nut.
- Tooth Length: The length of the hole used to capture the teeth of the T-Nut.
- Tooth Depth: The depth of the hole used to capture the teeth of the T-Nut.
- Tooth Angle: The angle between the teeth sloths on the fixture. This number comes from dividing the number of teeth (12) by the number of degrees in a circle (360).
| Part Dimensions | |
|---|---|
| Counterbore Radius | 10 mm |
| Counterbore Depth | 1.6 mm |
| Thread Radius | 4 mm |
| Thread Depth | 8.4 mm |
| Wall Thickness | 1.6 mm |
| Chamfer Length | 1 mm |
| Tooth Spacing | 9.75 mm |
| Tooth Width | 0.75 mm |
| Tooth Length | 3 mm |
| Dimension 3 | 4.4 mm |
| Dimension 3 | 30 degrees |
Design Considerations
When designing parts that use this component, you need to keep in mind the following design considerations
- Overhanging Holes: Holes in unsupported overhanging material can print poorly and lead to parts not fitting. Refer to the Hydra Research Design Rules section on overhanging holes for how to design an overhanging hole that can print without support
- Horizontally Printed Holes: Holes in the wall of a print can sag when printed, while this isn’t an issue for the threaded part of the hole, this can cause the passthrough hole to not pass through wall. When designing a hole meant to print horizontally, use a circumscribed octagon instead to eliminate the steep overhangs at the top of the circle.
Purchasing
| T-Nuts can be found at these links: | |
|---|---|
| Amazon | Part Amazon Link |