Would steel or aluminium be better?

While I’m waiting on my parts order for building my main subsystem, I started thinking about whether or not I should make the subsystem out of steel or aluminium. I have a heavy-duty-gear drive-train made of steel, but each side only has one motor. In past experiences I’ve only used aluminium, but feel as though this should be sturdier. I’m estimating the subsystem will be about 8-15 pounds with steel as the ramp will be my plexiglass change-up ramp. Any suggestions?

You should almost certainly make it out of aluminum. An aluminum chassis can be made just as strong as a steel chassis if built and it will be much lighter. This will allow you to get a much higher drive speed, and to have your motors burn out less frequently, making practicing much easier. It will also make it easier to carry and handle, another plus.
Also, you should pretty much always have at least 4 motors on your drive. It sounds like you only have 2, there is no downside to adding them, robots this year really don’t need 4 motors for scoring.


Thank you! The drive-train only has two motors for higher torque, but if my team decides against higher torque we can easily change it.

Steel doesn’t make your robot much sturdier good build quality will. Steel will only increase the material strength and since vex is not BattleBots it is worth the extra weight for steel.
Also, it’s a bad idea to have a heavy drivetrain made of steel with only one motor on each side. Because of F=MA with more mass you need more force required to reach the same acceleration. Your drive motors may over heat as well.


Thank you for the tips! I will show my team this comment to see if it persuades them to not have as much torque in the drive train.

I don’t think you understand torque; give this a read:
Torque - Wikipedia.
Adding more motors will increase the overall power, which can either be converted through gear ratios into more torque and less speed or vice versa.
Do some reading on how torque and speed is inversely related.
But overall, you generally want to have as much speed and torque as possible in your drive, which is why it is better to have more motors.


Aluminum is suitable for almost any application in VRC. Sometimes you may need higher material strength (such as bars that directly manipulate/lift game elements and take the brunt of the force), but usually as long as you properly support a subsystem, aluminum will do just fine.


Aluminum for drive trains and the frame, while steel for more heavy duty jobs or for doing something that might cause the aluminum to fail (i.e. the metal near a flywheel)


While the argument could be made for using steel for heavier duty functions, Aluminum will still stand up to the challenge 9 times out of 10. With the addition of being easier to cut, lighter weight, and all around better, Aluminum should be your first choice when building.


That is not torque. Fewer motors does not give you more torque. a two motor drive base will easily get pushed around on the field. Consider 4 or 6 motor drive base.

Steel components will be suitable if aluminum is not available.

Lightweight aluminum is critical for lifting mechanisms or balancing ramps.
Spin-up does not have any of those type of game features, so steel should be sufficient until your aluminum arrives.

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Steel should be used for the parts that experience high amounts of torque and aluminum should be for most of the bot especially for lifts. This year you are probably not using lifts so it really does not matter what you build most of the bot out of but one thing you should be aware of is if your robot is too heavy then your drive motors have a higher chance of overheating. So you should build what ever you can with aluminum to cut as much weight as you can.