Floating / Dynamic Center Hub Cap V3 (parametric with OpenSCAD)

Last update: 2025-11-13

Version 3: 

• Added embedded M3 nut for attaching swing to top cap
• Simplified openscad code for easy customization
• Online customizer

Version 2:

• Changed top cap connector to use m3 screws
• Fixed clearance issues
• Improved printability of swing
• Added generic tester
• Improved flexibility of clips

Older releases: https://github.com/Bob-vdV/floating-hub-cap/releases 

Description

Floating center cap where the logo stays upright as the wheel turns. Successfully tested on the Autobahn at speeds up to 200 km/h. It uses common M4 screws as weights. While it is originally designed for a 65mm outer diameter center cap, the diameter can be changed easily using OpenSCAD. Customization instructions are given below. 

Customization / Generation

To generate your own size of floating hub caps, you can either use the online customizer or a local installation of OpenSCAD. Steps for both options are described in their own paragraph below.

Online Customizer

1. Go to https://bobvdv.nl/floating-hub-cap
2. Open the customizer menu with the ‘Customize’ button
3. In the customizer on the right, change the settings at the top under main parameters. The last image shows how to measure these parameters.
4. For each part in the dropdown menu selected part, render it (F6) and export it to STL (F7).
5. You can add your own logo by combining the plain top cap and your logo in your slicer. Alternatively, you can add a vinyl sticker to the plain cap. For logo alignment: The arrow on the back of the top cap points down. 

Local OpenSCAD installation

1. Download OpenSCAD nightly here: https://openscad.org/downloads.html#snapshots-windows
2. Download the OpenSCAD source files from Github:  https://github.com/Bob-vdV/floating-hub-cap (Code → Download ZIP)
3. In OpenSCAD, open centercap_main.scad. 
4. Make sure the customizer is enabled. You can enable it at Window → customizer in the toolbar.
5. Render a preview (F5) of the part to show customizer settings.
6. In the customizer on the right, change the settings at the top under main parameters. The last image shows how to measure these parameters.
7. For each part in the dropdown menu selected part, render it (F6) and export it to STL (F7).
8. You can add your own logo by combining the plain top cap and your logo in your slicer. Alternatively, you can add a vinyl sticker to the plain cap. For logo alignment: The arrow on the back of the top cap points down. 

Printing

Print with a heat- and UV-resistant material (PETG, ASA, …)

Standard settings are okay for most parts. Supports are only necessary for the top covers in specific orientations. For the base, make sure that you have good layer adhesion for the clips, as otherwise they might break.

Print one base, swing and top for each wheel. 

For the flat top cover, the logo can be printed in a different color using a filament change. For a good surface finish I recommend printing it with supports, the logo side up and using hilbert curves as top infill.

Assembling

For assembly of 4 floating hub caps you need:

• 4x 608 bearings (BONES REDS recommended for low friction)
• 20x M4 10mm screws
• 20x or 40x M4 nuts 
• 4x M3 14mm screws
• 4x M3 nuts

You can choose the number of nuts depending on the quality of the bearings and maximum speed, where higher speeds require more nuts (weight). Theoretical maximum speed calculation is described in the testing section below.

Assembly steps for one hub cap:

1. Check if the base fits your wheel
2. Insert the bearing into the base. This is a tight fit, so you might need to hammer it in. A sacrificial calibration cube can be used to hammer on to avoid damaging the bearing. 
3. For the swing, first add an M4 nut to each M4 screw if you want extra weight. Then insert a nut in each hole in the swing and add the screws.
4. Insert the swing into the bearing and make sure it can spin freely. 
5. Insert the M3 nut into the top cap and check if the holes align.
6. Align the swing with the arrow on the top cap and insert the top cap into the bearing. 
7. While holding the swing and top cap upside down, screw in the M3 screw through the shaft of the swing. 
8. Make sure everything can spin freely. 

Testing

The maximum speed can be determined with the hubcap tester and a drill. Film it with a slow-motion camera when it is stable to get the max rotations per second and use the following formula:

max_speed (km/h) = tire_diam (m) x π x 3.6 x rotations_per_sec

In my case with 40x nuts, 64cm tires and 40 rps this gives 290 km/h.

Using only 20x nuts it can rotate at 24 rps, which gives 170 km/h maximum. 

Share it!

I would love to see other people's results, so please post a make or create your own top cover design.

A like is also appreciated!