Just curious what exactly does the drill motor gearbox provided in the kit actually do, does it provide a lot more torque or speed? What are the advantages and disadvantages of using them? Is it most efficient to have just the drill motor or the drill motor with only gearbox or drill motor with both gearbox and custom gear box or drill motor with custom gearbox only?
The drill transmission (and transmissions, more or less generally) trade speed for torque.
The power (speed * torque) only decreases with each interface. To explain why this is true is more or less an unanwerable question that at bottom comes down to “because that is the way the world works.” Yes, we can always hide behind a lot of complex talk about the direction of time, concepts like entropy and observed “laws” like the Second Law of Thermodynamics (note the capital letters – oooh, it HAS to be true if it has capital letters
Anyway, the quantity (speed * torque) is at its maximum at the shaft of the motor. It decreases with each gearpair, but you can lower the speed and increase the torque. That is what the drill transmissions do. For example, in low gear, they decrease the speed by approximately 60. They increase the torque be something like 50.
In FIRST type applications, we tend to need more torque and less speed, so the drill transmission are good for this job.
Are they the most effecient?
This again is a very complex question. They are NOT the most efficient in terms of power. Planetary gears are not nearly as efficient as a well designed straight forward gearbox of the same ratio would be.
BUT… in terms of size, well, they are quite efficient. It would be difficult to design a gearbox of the same ratio from scratch in such a tight package.
ALSO… in terms of engineering effort, they are very efficient indeed. It takes almost no engineering effort to use them while it takes quite a bit of engineering to design your own from from scratch.
Finally, there is the shifter. In terms of a shifting gearbox, they are a lot of bang for the buck. It take little effort to use them and to make them shift (relatively little effort that is) compared to designing a shifting transmission from scratch. Ask those who have done it this year – I think they will agree that it is an efficient design for that feature – but if it does not quite give you the ratio you want, then perhaps not.
As I said, these are difficult questions.