Vex Axle Material Property Question

Does anybody have the material used or the stress/strain/sheer values handy for the vex axle? In writing some curriculum it would be great to have them for the section discussing the transmission of torque.

Any unit is fine.

Sigh. I asked this a few months ago and got nothing back about the properties. Got a discussion going but nothing about the exatc properties of the steel.

So I chose the weakest steel I could find and if it was better then yipee! Call it a factor of safety discussion at that point. “It can’t be any worse than this steel”

I think the steel axle is rolled and extruded into a square bar and is a realtively low grade steel with a zinc coating. I doubt it is treated or hardened given the realtively easy twisting ability seen in the field.

If anyone has some good lab equipment to help benchmark these parts that would be an awesome project for a college team to do and share with the community.

It seems to me that Vex axle material is essentially 1/8 square key stock. This means that it is possible that VEX could purchase it from a variety of wholesale sources, and that this year’s axles could be slightly different from last years’.

Here’s two slightly different key stocks, with slightly different material properties listed… but I’d follow the approach of going with a generic mild steel. For most applications you will likely be more concerned about the modulus of elasticity (how much it bends under a given load) rather than yield strength (whether it stays bent following a given load), and the modulus of elasticity is reasonably constant across a wide range of steel.


The vex material lists the Steel parts as Cold Rolled. IIRC, this adds some strength to it… but I’m not a mechanical engineer…