Why do a lot of your projects use a modified servo?

I have seen a couple of projects that use a modified servo which appears to remove the circuit board and simply hook up the power supply to the DC motor. The only components that seem to be left in the servo are the DC motor, a few gears and the servo box. Why then couldn't I just use a DC motor, they tend to be far less expensive than the servo (~$1 for a DC motor compared to >$3 in bulk and up to $12 if you are not buying in bulk)? In other words could I use a DC motor and get similar results?

randofo2 months ago

In short:

1) DC motors tend to spin too fast and have too little torque for direct drive of most mechanisms
2) Attaching things to DC motor shafts tends to be challenging for beginners
3) Geared DC motors tend to be surplus and non-uniform from one to the next
4) Both attaching things to geared motor shafts, and geared motors to things can be challenging
5) Surplus DC motors tend to have a wide range of power requirements
6) Servos are of a uniform size and have fairly uniform attachments.
7) Continuous servos also have fairly universal speed and power requirement.

All of that said, if you think it is easier for yourself to use a DC motor, feel free.