Is there a large difference between full-step and half-step stepper motors' torque at very low speeds?

Question

I'm using a NEMA 23 for a solar tracker, which means my mechanism will move a single step every 5~10 minutes, and the step angle is 1.8 degrees which I need to bring down to 0.01 degrees.

Now I need to ensure that there is enough torque to move the mechanism, so I have two options, option 1, either use a large set of gears (compound gear) to reach the desired step angle, which is something I'm trying to avoid since I'm not familiar with designing gears and the compound gear will be difficult to assemble with the body of the tracker.

Option 2, is half-stepping and using a smaller compound gear (less total teeth in total).

Is there much difference between Half-stepping and Full-stepping torque? And. how much of a difference? For me, accuracy and torque are much more important than speed.

Answer 1

No, there's not much difference in torque, so you're good there.

However, going down to 0.01 degrees from 1.8 degrees is pretty ambitious, accuracy-wise. Moreover, when you do full steps you can go from the motor's resting position to the next resting position. When you half-step, you have to keep power applied.

If you were to go in 0.01 degree steps, via gearing or whatever, then you could do a full step every 2.4 seconds and power down between steps -- so most of the time the motor wouldn't be powered. On the down side, while in theory your output shaft would advance by 0.01 degree at each step, in practice without a lot of effort you'd experience backlash or mechanical compliance or something that'd make your pointing accuracy much less.