Roll Cage

[NoHachi]

If you are running in some kind of racing class: easy - just use whats prescibed.

If not: don't do a cage. You really shouldn't be driving a caged car anytime without a helmet on. Something about a melon and a metal baseballbat.

A poorly constructed (or welded - usually even more important) cage is usually more dangerous then no cage.. You are now sitting in the car with a random colllection of baseball bats, no fun in that.

That said..the design is actually quite simple.. usual rules:
1: Triangles provide stiffness.
2: Always have the tubes come together in a single point
3: Always use correct fillets/cuts to be able to do no.2 (difficult)
3: Never have a bar connect in the middle of another bar (see no.2)
4: Have a maximum of 3 bends in any tube
5: Use thick plates to help spread loads/introduce them into the chassis

In the end, its not the design that kills a cage, its the execution. Getting every connection and every weld perfect is difficult. Thats why its probably better left to people doing that kind of work every day.

Example of a poor cage during a crash:


That sure helped eh!