What is a grub screw?

A grub screw is basically just a tiny screw with no head on it, and it's commonly used in all sorts of different machines and devices. In the world of RC cars, for example, you might find a grub screw in an electric motor.

I actually had an experience with a grub screw recently when I was working on my RC car's motor. You see, the motor has a little metal pinion gear on the end of it, and the grub screw is used to hold that gear in place on the motor shaft.

So, I needed to remove the pinion gear from the motor shaft so I could clean it and put on a new one. I used a tiny Allen wrench to loosen the grub screw, and then the gear slid right off. Then, when I was ready to put the new gear on, I tightened the grub screw back down so that it held the gear firmly in place.

It might seem like a small thing, but the grub screw is actually really important in making sure that the motor works properly. Without the grub screw, the gear could slip or come off altogether, which would cause the motor to stop working or even get damaged.