Very slow speed motors : Timelapse project

Hello
I have decided to make a panning head for a DSLR. Since this is for timelapse, I need speeds ranging from 1rpm to 1/1000 rpm.

Since I am in India, it means I can only buy stuff from aliexpress or ebay global sellers.

I have a few questions.

  1. I see stepper motors with 1.8 degree step angle coupled with 14:1 gearboxes. Does it mean that the end shaft will turn 1.8/14 degrees with each step?
    Example : This motor
    http://www.aliexpress.com/item/New-Best-Gear-ratio-14-1-Planetary-Gearbox-stepper-motor-Nema-17-0-8A-Geared-Stepper/32310531945.html?spm=2114.01020208.3.12.SdK4TQ&ws_ab_test=201407_4,201444_5,201409_1

I will need to the shaft to some kind of plate with a 3/4" screw to mount a tripod head. What do you recommend

For driving the motor, I want some kind of 5-7V driver. The reason is I can use a USB powerbank or 2*LiIon cells. What do you recommend.

Can you point me to the required audrino board and software so I can change rotational speed in the field. I would need some kind of display.
I want very basic setup.

For example a divider value
1 = Full speed = 1rpm
5 = 1/5 rpm
1000 = 1/1000 RPM

So very basic motion control. Nothing fancy.

If any of you have seen a guide to making such a setup(step by step with pictures) please let me know.

Since I can buy only from aliexpress or ebay international, unique fancy parts are out of question.

I’d suggest using a microstepping stepper driver like the A4988 or DRV8825, otherwise you might have
vibration issues. Microstepping also gives you smaller steps (but note precision isn’t that great, expect
to get down to 1/10 of a full step reasonably well, so 1/8th or 1/16th microstepping is plenty).

Yes you are right about the gearing, but gears typically have backlash which can be an issue (normally
not if only going in one direction)

I cannot see any data about the coil resistance of the motor but I suspect that 5v to 7v would be too low. In any case I thing the A4988 needs a minimum of 8v.

You should also keep in mind that stepper motors are very inefficient as they need full power all the time to hold position. They are not really suited to battery operation.

A DC motor with a worm-drive might be more suitable for your application - but the obvious problem is that it does not have position control. However you could add a rotary encoder to the output shaft for position detection.

...R
Stepper Motor Basics