Continuing the discussion from What are the changes between the different nightly FW builds?:
There is a lot of info out there about each of these filaments. Each filament has unique combinations of stiffness, hardness, melt temperatures and so on. When you cannot satisfy the strength, thermal resistance and wear resistance needed for a part with a particular plastic, you know it’s time to move on to a CNC made metal part.
Pulleys for example, can be printed with anything. There are guides which are really important to read before starting up. But the operating conditions matter. For esk8 where the speeds and forces are high, there is a substantial amount of heat and friction build up that can occur, making low melt temp plastics inadequate. For the small diameter of the motor pulley, the forces exerted will deform the small teeth on the pulley. That’s because the small diameter means only a few teeth of the belt are in contact with the pulley at once. So 100% of the load of you braking and accelerating is spread across only a few teeth. For the wheel pulley, the diameter is larger so there is more tooth engagement. Many have successfully printed wheel pulleys.
Motor pulleys should be steel. Aluminum is not often recommended but I have no experience with it