I need an Adult haha

Using Arduino Motors, Mechanics, Power and CNC
1

Hey all,
I am incredibly new to this so bare with me.

Heres what I have

-2 NEMA 17 Stepper Motors (red, yellow, green, gray)
-Arduino UNO R3
-OSEPP Motor & Servo Sheild
-6 double AA battery pack
-B10K potentiometer
-B50K Potentiometer
-Jumper cables, bread board and other misc parts

heres what im trying to do.

Id like to have 1 stepper motor running forward, and one running in reverse. Id like to be able to control the speed of both steppers with a potentiometer, and i need it to run very very slow.

I work for a well known watch company in Detroit as a videographer and my plan is to make a rig that I can hookup a watch to and make it turn around very very slow infinitely. Or basically a vertical turn table. I have some machining experience so im not worried about how im going to make the clamps for the straps or anything. But I have spent about 2 days trying to figure out how to make this work. Ive been trying to learn some code and im not getting confused but im getting overwhelmed and I dont wanna tap out but I just dont know what im doing wrong. I feel like, for what im trying to accomplish, I should have figured this out by now but im lost. Can anyone help me out?

2

If you have some code that is not doing what you want then post it and tell us in as much detail as possible {A} what it actually does and {B} what you want it to do that is different.

In the meantime these links may help
Stepper Motor Basics
Simple Stepper Code

Stepper motors are inefficient and not really suitable for battery power because they draw full power even when stationary. However you can easily make a stepper motor take 1 step every month if you that's all that is needed.

...R

3

That should be easy enough although that motor shield is totally unsuitable for driving low-impedance stepper motors. You need a driver based on an A4988 or DRV8825 for small motors up to 1.4A.

4

Are you making a store display or like an automatic watch winder? What do you mean infinitely? What are the torque requirements? Why do you think you need a microcontroller when something as stupid simple as wiring a 5v wall wart to a dumb 5v dc motor will spin infinitely?

5

Well to be honest, I don’t know the torque requirements. I’m not an engineer admittedly, but most Motors I’ve found locally have way too many rpms for what I’m trying to do. I guess here’s some more detail.

Often I’m shooting on a macro lens at 180mm, so super close up on the watch where half the dial can cover the frame, (I’m not always shooting it that way) but because I’m so close up the watch, it will show the tiniest fatigue that human hands can give as I’m sure you all know, no one can keep their hands completely still. You’d have to be dead or a rock.

I shoot in high speed slow motion sometimes, but when it comes to the face of the watch, the watch designers don’t like to see the second hand ticking in slow motion as that’s not how it ticks in real time.

So my thought was to hook up regular hobby motors on a potentiometer and and slow it down, but as I said, everything that I’m finding (without ordering on the internet) is like 50,000rpmish and up.

So I saw the stepper Motors which looked like they were able to slow down to a considerable speed (just eye balling via youtube) and decided on those. And if I have to add gears, not a big deal.

Here’s another factor, I have to be able to stretch the watch so that the straps and movement appear flat. I don’t have to see the very top buckle, or the very bottom of the bottom strap, so my plan was to clamp those areas and stretch the watch out. It doesn’t require a lot of tension as the straps we use are brand new and for the most part lay flat by themselves. But if you have ever held a watch up with your bare hand, pinching the buckle with your fingers in one hand only, you’ll notice the weight of the Movement, pulls the bottom of the movement backwards and not straight up and down.

Again guys, really new to this. But here’s a video I found (don’t have to watch all of it, maybe 40 seconds will do) but this is how I’d like both Motors to react, only difference from this video and my build is that I want two stepper Motors with one running in reverse.

6

How To Control a Stepper Motor with A4988 Driver and Arduino - YouTube sorry that’s the link

7

ddonaldson86:
So I saw the stepper Motors which looked like they were able to slow down to a considerable speed (just eye balling via youtube) and decided on those. And if I have to add gears, not a big deal.

If you're 'filming' in slow motion consider this - a stepper motor steps. That is, when it's commanded to move it does so suddenly in discrete increments, usually 1.8° per step. Meaning, it's not a continuous, smooth movement like you'd get from a regular D.C. motor.

Since the movement of the hands of the watch is an issue, this may be also - although gearing it down may reduce the jerk to an acceptable range.

8

Yeah, steppers . . . . step.
And just as how the wheels on your car aren't spinning at the 3000rpm that your engine crankshaft spins at, reduction gears are used in basically every application for a reason. I can only think of fans as being a usual exception.

I still have no idea what it is you're trying to accomplish, I may just lack the imagination required to turn your words into a clear picture.

Simply pulling the crown not an option? Or pulling the battery if hand motion is a problem? Or are you specifically in the business of slow-mo filming solar cell watches?

9

Why two motors for one turntable?

Some numbers are needed, "very very slow" actually means almost nothing - is that 0.1 rpm
or 0.001rpm or 0.00000001 rpm?

So can quantify things like: Lowest/highest speed wanted? Accuracy of speed? Accuracy of angle?
Minimum single step movement angle? Maximum allowable backlash?

10

ok i'll try to paint a picture

take your left hand

hold it up in front of your face (back side of hand facing you)

pretend your wrist is a stepper motor and your hand is the watch

pretend another stepper motor is clamped to your middle finger's finger nail.

rotate your hand so that your fingers are still pointed to the ceiling but your thumb is rotating right to left

imagine you dont have a wrist, keep rotating your hand until it gets back into its original position, and keep rotating about 6 "revolutions" we'll say

I hope that helps

if not then try to think about it like this.

I have two stepper motors, I want 1 stepper motor to move forward, and 1 stepper motor to move in reverse. Both stepper motors should move the exact same speed and I want the speed controlled by a potentiometer. The slower the better.

-don't think about the torque
-don't think about the watch
-dont think about how its rigged
-dont think about slow motion
-dont think about gear ratio's
-dont think about anything other than is listed

please dont see that as being insulting as I see everyones reply with respect. But again, here is the objective

I have two stepper motors, I want 1 stepper motor to move forward, and 1 stepper motor to move in reverse. Both stepper motors should move the exact same speed and I want the speed controlled by a potentiometer. The slower the better.

Thank you

11

Sorry, my will-power has failed me.

What does an Adult haha look like?

I have only seem them in the larva state.

...R

12

Hi ddonaldson86,

I'm not familiar with the OSEPP shield or its library,
But if you used stepper drivers like the example image below or adapted this to your needs with the OSEPP library the here's an example.

I pinched basic stepper potentiometer code from "John Saunders NYCCNC http://www.nyccnc.com/"
and added the second stepper that goes in the opposite direction.

/* Potentiometer Program
John Saunders NYCCNC http://www.nyccnc.com/
  
microstep driver ST-M5045
Pul+ goes to +5V
Pul- goes to Arduino Pin 9
Dir+ goes to +5V
Dir- goes to to Arduino Pin 8
Enable+ to nothing
Enable- to nothing
*/

int sensorPin = A3;
int sensorValue = 0;

void setup() {                
  pinMode(8, OUTPUT);  //direction pin
  pinMode(9, OUTPUT); //step pin

  pinMode(6, OUTPUT);  //direction pin
  pinMode(7, OUTPUT); //step pin
  
  digitalWrite(8, LOW);
  digitalWrite(9, LOW);
  
  digitalWrite(6, HIGH);
  digitalWrite(7, LOW);
}

void loop() {
  sensorValue = analogRead(sensorPin);
  sensorValue = map(sensorValue,0,1023,3600,1);
  digitalWrite(9, HIGH);
  digitalWrite(7, HIGH);
  delayMicroseconds(3);          
  digitalWrite(9, LOW);
  digitalWrite(7, LOW);
  delayMicroseconds(sensorValue);
 }
13

Yeah, okay, it's not just me. You are really really bad at explaining. It's okay. Most people are.

Maybe if you could explain things using a more sensical (wtf spell check, that's totally a word) axis of rotation terminology.

X axis going left to right. Y axis going up and down. Z axis going back and forth (as in through your computer screen)

A motor sitting on a table with its spindle pointing to the ceiling has a 'Y axis' axis of rotation, for example.

Now. Replace that shit like 'pretend your hand is a watch' or 'duct tape a stepper to your fingernail' with something that makes sense and see where that gets us.

Also, are you saying you already have stepper motors on hand, even though steppers sound a lot like not what you want?

14

Which direction is forwards?

Does the Arduino have to change the direction of rotation?

You may need to synchronise the stepper steps to the frame rate of your camera. With low speeds, that is easy - make a step, take a frame. That's how all the timelapse+slider guys do it. For normal and high speed, you are going to need a camera which has that kind of sync built-in.

15

Are you thinking of something like this?

16

dougp:
Are you thinking of something like this?

So that's what they look like :slight_smile:

...R

17

You could buy a lazy susan and pay a woman named susan to spin it for that price!

18

INTP:
You could buy a lazy susan and pay a woman named susan to spin it for that price!

Perhaps. But it wouldn't look as elegant as the one linked.