Motorbike / bicycle helmet stand

This helmet stand serves as a resting place for your helmet on your work desk.

The file included should work with any helmet (a bicycle helmet is shown), although it was designed for a motorcycle helmet 210 mm wide.

Customizing

There are only two adjustable parameters:

• Width of the helmet in millimeters
• Height of the bottom of the "bowl" from the table

The design script assumes a cranial index of 0.83 (on the high side of average), and uses that to calculate the length of an ellipsoid based on the width provided. There are other "advanced" parameters that you can adjust if you run the script from OpenSCAD.

Print settings

• 0.3 mm layer height
• 2 perimeters
• 0 bottom layers (if you have good build plate adhesion). This saves some material.
• 20% cubic infill
• No supports needed

How I designed this

I designed this in response to a request on Reddit, because I was interested in the problem in OpenSCAD of beveling an edge that curves around in all three dimensions. Here, the edge arises from an ellipsoid subtracted from an extrusion of a 2D curve.

One way to solve this is to use the minkowski() sum operation in OpenSCAD using an octahedron as the shape to add all over, but this turned out to be painfully slow, and not feasible for an online customizer.

This design, on the other hand, generates the beveled curve quickly and efficiently. I solved the problem with mathematics. The top edge is is each point of the 2D curve projected upward until it intersects an ellipsoid. The inner bevel is the same 2D curve offset 3 mm inward, projected upward to another ellipsoid that's 3 mm smaller in its minor radius. It isn't perfect, but it's close enough, it looks good, and it's fast.

Category: Sport & Outdoors