How to 3D Print Bearing

Hello Makers, welcome to my new instructable about printing and testing 3D printed Bearings. In this instructable, we will learn how we can design a printable bearing model without any extra assembly and print it. However, these bearings are for small toys and other 3D printed tools where the function of the bearing is not critical because they are made from PLA (Polylactic acid) which is a kind of plastic and they are obviously not strong as the metal bearings. So let’s get craken’

List of things that are used in this project.

1. PLA spool 1.75mm

2. 3D Printer (Ender 3)

3. CAD software (Inventor optional)

4. Slicer (Prusa Slicer optional)

Optional: as CAD files, STL and Gcode files are attached below.

Bearings have an important role in any mechanical machine, hence their design is cumbersome with many mathematical formulas and equations. So, I kinda cheat here because I am concerned about only one thing which is its functionality, and therefore, I skipped the calculation part ( in my defense, the strength of the 3D printed part is uncertain because of the variety of PLA producers, printing conditions, layer height, temperature, etc.).
Printing ball bearings in FDM printers seems impossible that is why our rolling elements are not ball but kind of grooved rollers with a clearance of 0.25mm on each side (0.5mm in total) as shown in the photo. This air gap is very important as this gap allows the bearing to rotate and we cannot give too small an air gap because then the material of the roller will stick with the bearing casing while printing. The bearing casting is also has a slot to hold the rollers in their position, and since we gave 0.5mm clearance there will be a small play in the bearing.

Another important factor is the number of rollers, if the number of rollers is less, then the bearing will fell apart and if it's more then they will stick together and the bearing won't move. The number of rollers in the bearing with the following dimensions seems good with 11 or 12 (I prefer 11).

The dimension of the bearing is as follows.

Inner diameter = 10 mm

Outer diameter = 30 mm

Number of roller = 11

The thickness of bearing casing = 5 mm

After Designing the next step is to upload the .gcode file into the printer. To do so, we first have to save the file in STL format and then slice it with any slicer. As there are no overhangs in the design we don't need any support structure and the width of the bearing is quite sufficient so we can also turn off the brims (as we don't need extra material for bed adhesion) and simply slice it. I have used Prusa Slicer with 20% of infill for this model and after slicing, we have to upload the gcode file into the 3D printer.

The bearing looks quite nice and more importantly, IT ROLLS. However, there is a play in Y-axis which we already knew. The main advantage of the printed bearing is customization (any dimension of Inner and outer diameter, but not too small) or we can design bearings with slots so that the shaft can easily fit inside.

For more information, you can check out this youtube video

The files are also attached below.