Incorrect contact normal direction for thin colliders?

Hi guys, first time posting here. Am having some issues with thin colliders.

My sword has a thin stick-like collider (0.03, 0.02, 1), and my goal is to not let two swords pass through each other.

I am using the PID controller from this answer:, so the swords are moved by force and torque.

However, pass through still happens. Upon closer inspection, I noticed that sometimes the contact normal is pointing towards the other collider, instead of away from it (see: Small Collider - Incorrect Collision Normal Direction - YouTube), so perhaps the physics engine pushes in that direction and causes the thin colliders to pass through each other?

I tried scaling up the swords by a factor of 10 and decreasing the DefaultContactOffset from 1e-05 to 1e-08, but these doesn’t seem to help.

Am I doing something wrong? Or is this a Unity bug?

Any inputs are much appreciated!

When adding the “box collider” tag, I realized that I have never tried capsule collider before.

Turns out that capsule collider works so much better than box collider, so far no pass through has occurred in my testing.

Thank god I finally can proceed forward with my project :')