Increasing a stepper motor's bridge current fro 1.24 A to 3.13 A does what besides produce more heat?

50kΩ to 1.6kΩ

Or does calculations based off nominal values not matter much?

That's holding current, right? That translates into torque (holding/rotating)

It might help to think of all motors as current-based devices. AC/DC/Brushless - the more current (over time), the more magnetism, so the more torque, period. They just happen to have their ratings expressed in Volts because more people are familiar with Volts. But Voltage is only one aspect of the motor (and arguably, is not the most descriptive part of it.)

@rdtsc The only fundamental characteristic of a motor that's voltage-based is the max rotation speed.

@W5VO I just took the 3.3V*30/(30+50)

= 1.24 A