This is a spool hub that uses very little material and locks into the spool with spring force. It can be easily modified in OpenSCAD. ( See below )

The design shows that even PLA can be used to create quite robust springs as long as they are long, relatively thin and printed with perimeters only.

I have exported the model in a view different diameters both for a 8mm axis as well as for 608 type bearings. The mm dimensions in the filenames are the uncompressed size of the hub. So select one that is a bit larger than your spool hole for good clamping.

This customizable ring clip is very useful in connection with the hub: Spring Clip

Slicing

Slice with enough perimeters to fill the root of the vane like displayed on the right. This creates a stronger part compared to having infill there like on the left

Customizing in OpenSCAD

To create your own version download the free OpenSCAD application that is available for Linux, macOS and Windows.

Download the “springy-hub.scad” file, open it, and if not already the case display the “Customizer” tab by selecting the entry in the "Window" menu.

All customizable parameters for this model are documented in the user interface.

Select “Render” and then export your generated model.

If you adapt the hub to your spool sizes make the diameter bigger than the maximum hole size you want it to fit. As a rule of thumb about 5% plus. This guarantees that the springs have enough tension to lock it in.

Happy Printing & Customizing