Carbon Fiber

[ChrisH]

Carbon fiber and graphite fiber are the same thing. Carbon fiber is on the exotic materials list so any composites using it would be illegal. This is a continuing disappointment to me because making airplanes out of carbon fiber is what I do for a living. I could get as much as I need to build robots for a decade by asking for some obsolete material.

But I also understand WHY they prohibit it. While carbon composites are very strong for their weight, when they to break they shatter. Leaving all kinds of splinters all over the place. No only that, but failure generally occurs without much visual warning. You see the object bending, but there is no yield to tell you to back off.

My co-workers and I regard graphite splinters and minor cuts to be an occupational hazard. If you are going to work with the stuff you just live with it. Cutting and drilling these composites without splintering requires special knowledge and special cutters or drills. These can be very expensive so there would be great temptation NOT to use the proper equipment.

Fiberglass on the other hand is much friendlier. While it too tends to fail suddenly, the remains are not as likely to stab you. While it is somewhat heavier than carbon, it is still lighter than steel and has a similar modulus. Fiberglass can in fact be stronger than carbon, but it is not quite as stiff.

All in all, I think fiberglass makes much more sense for FIRST teams than carbon.

BTW has anybody else noticed that while they put a $ limit on how much you spend for parts for your robot, they did not limit the amount you spend for tooling? Maybe I just noticed because we routinely spend tens of thousands to fabricate tools to make parts worth hundreds.