I am new here to the forum, so I hope I am posting in the right section. I am working on a school project, planning to design a robotic wing. I am first devising a way to use gears with a servo motor (Hitec MG995 - http://www.electronicoscaldas.com/datasheet/MG995_Tower-Pro.pdf) as the driver. As you can see, it has a stall torque of 8.5 to 10 kgf-cm (not much, hence why I am planning to use gears). What I am trying to find out is if adding a gear to the end of the shaft will add resistance to the motor's rotation, and therefore will I have to consider that resistance when calculating the overall output? I tried to look this up online, but nothing specifies whether or not that will be the case (in fact, a lot of explanations about how gears work don't seem to consider the mass of the gear adding any resistance to the rotational force of the driving force, i.e. the motor). Since I am hoping to incorporate metal gears into the design, this is an important question whose answer I cannot find. Also, while I am posting this, I may as well ask: I am wondering if anyone can consider good material to work with that is both light yet sturdy and is able to hold a decent amount of weight. I've considered aluminum, but I do plan to make this a little bit bigger so as to be proportional to a human so I don't know if it may be too much weight. Any help is greatly appreciated.