Why use timing belt drives in Stepper Driven Robotic Arm

This may be a noob question. I am sorry if it is but I am new to this field. I am working on a design of SCARA Robot and I am using Stepper Motors to drive it. In many youtube videos, I have seen that they increase the torque using timing belts. Now I understand that in most cases timing belts are used for keeping motors away from the joints to reduce inertia. But I don't understand why they use ratio in belt drive. As far as I know, Stepper motors provide high torque at low speeds and vice versa. Then Stepper Motor should provide that much torque at reduced speed by default, right? Or I am missing something?

• they increase the torque ... you answered your own question – jsotola Jun 1 at 16:21
• Thanks for the reply. But I think they would provide more torque at low speeds by themselves instead of using a belt drive and then turning the Stepper motor at high speeds (thus producing low torque) and then increasing it using a timing belt. Why would they use a timing belt to do something that the motor itself can do? or is it that the torque that they want is outside the stepper motor's torque-speed characteristics? and can not achieve by reduced speed of stepper motor? – Nirav Joshi Jun 2 at 4:58
• those are good questions ... you could ask the they ... or you could analyze a design – jsotola Jun 2 at 5:02
• You are right. I should have asked them first. Thanks. – Nirav Joshi Jun 2 at 5:08