Configurable joint secondary axis - is it perpendicular to the first one?

Unity Engine
1

Is the secondary joint axis perpendicular/orthogonal to the main axis of configurable joint?

Common sense says it should be, but the documentation says nothing regarding that.

2

Yes.

3

Old answer look at the following one

There was a very old Unity3 video about the configurable joint done by “3D Buzz” where it explores every aspect of it. I’m still searching for it. It was super awesome, the best one and probably the only one. Unfortunately, he is gone (not with us). And his content is zipped too big. (another link: youtube video : ZF0XX0La4JM )
The original link was:

Buzz Physics - 13 - Configurable Joint - 3DBuzz
http://www.3dbuzz.com/training/view/unity-fundamentals/physics/13-configurable-joint

I found a 3DBuzz Archive: https://archive.org/details/3dbuzz-archive/developing-rigging-systems-part-02/002-blueprint-system/101-105-hinge-joint-theory.mp4
Probably scrolling the very long list there is 13 Configurable Joint

I’m still searching for that video because was so good.
Also, I remember also a UDK3 video with another name. But there is not that much as a video tutorial.

Anyway in it explains how to use each axis. The first one is the main one. The last one does not have all the capability of the first one. So is better not to touch the axis and use the default first and if you need it, the second one. I remember that I use to place a parent transform to rotate it and place it correctly instead of rotating the axis around. This was important to keep performance and characteristics. Also To make the configuration is the same as another joint. I presume is the hinge joint.

Related
Screenshot Configurable Joint movement
Explanation Configurable joints in-depth documentation / tutorial / for dummies
Guid The Complete Guide To Unity's Configurable Joints - WireWhiz

4

I find it!!!

BEST CONFIGURABLE JOINT VIDEO COURSE

Is number is 3DBuzz video number 5650. To understand this video you need first to look at video 5647 hinge joint.

Part 1) Hinge Joint Tutorial

Part 2) Configurable Joint Tutorial

The series starts at video 5638 and is about the default PhysX in Unity2 or 3 but is still an excellent beginner-intermediate free course for understanding the various properties.