Which stepper or servo motor is right for me!

Hello guys! I'm making a two axis slider, but I have a little problem with the motor selction

With a motor I want move horizontally or vertically 2Kg of things...on this slide I want to add another motor for the rotation

For start, can you help me to fine the right motor with the right torque for this application?? I prefer something about 5V or 12V and use the A4988 driver or similar (I will choose it for the littel dimension)

Speed and precision for now is not a problem I wait your opinion thank you!

1.Why would you prefer 5V or 12V to power the driver? -> The higher the voltage the better you can control the stepper.

  1. Are you limited by the external dimensions and/or weight of the steppers?

1 -Because I want use it without AC just battery 2 -The dimension I don't think but the weight have affect on the weight to move (the horizontal motor I don't think but the rotation motor I have to install on the slide)

Stepper motors are very inefficient and not suited to battery operation. Also they perform better with higher voltages - I think an A4988 can go to 30v or more.

The choice of stepper motor depends on the torque required. There is a suggestion for a simple way of measuring torque in Stepper Motor Basics

...R

Understand.. So for this application are better servo motor? Because the maximum speed isn't a problem but I liked to send position and speed and I didn't find a library for make this with servo.. I choose stepper motor just for this problem... But I prefer servo for precision and dimension.. There's a library for command the position at a programmable speed?

When you say "servo" do you mean a hobby servo such as are used for controlling model aircraft?

A stepper motor should be much more precise than a hobby servo. But hobby servos are very easy to work with. Control them with the Arduino Servo library.

...R

Yes...in realty I don't want unplug my dji phantom 3 drone motor :D

Thank you Robin2 for your time, but from what I see on internet to the hobby servo I can say "Go to 0°" or "Go to 180°"

And It can be usefull for the rotation on the slide...

But for the slide I need something "make 13mm at speed 0.1mm/s" or (from a 0 reference) "make 15000mm at speed 100mm/s" or having a speed in percentual... And from what I see is not easy to do with servo, or I'm in error?

Now I was thinking about a DC motor with a rotative encoder...but I have some fear for the cicle time and the encoder task, resolution and maximum speed.. Because sometime I need to move something like 2.5mm every 30sec...Some time I need to make 1500mm in 5 seconds or a little more.....(but for this I can use switch and don't take in consideration encoder)

What do you think about this solution?

As already pointed out, you have to [u]measure[/u] the required torque (or force, which you convert to torque) before you can choose a motor.

Have you already built the slider? If so, post some pictures.

forna91: Now I was thinking about a DC motor with a rotative encoder...but I have some fear for the cicle time and the encoder task, resolution and maximum speed.. Because sometime I need to move something like 2.5mm every 30sec...Some time I need to make 1500mm in 5 seconds or a little more.....(but for this I can use switch and don't take in consideration encoder)

That is a huge range of speeds - a ratio of 3600:1 if my maths is correct.

And I agree it is unlikely to be practical to control a continuous rotation hobby servo to get specific speeds without using a rotary encoder. In effect a continuous rotation servo is just a DC motor in a convenient package.

A stepper motor has the advantage that it can step as slowly as you like. But when doing that it will be jerky - maybe that is OK. Using microstepping would make it smoother - but not completely smooth like a DC motor with a large gear reduction.

Making a stepper motor work fast is a bigger challenge and I can't fiigure from your data how many steps per second might be needed for 1500mm in 5 secs.

But it may be an even bigger challenge to make a DC motor with a large gear reduction reach the desired top speed.

...R

jremington:
As already pointed out, you have to measure the required torque (or force, which you convert to torque) before you can choose a motor.

Have you already built the slider? If so, post some pictures.

Eeeh…I don’t know the torque I need…I’m here for this :roll_eyes:

SO

The slide is this:

But now I want remake this with a belt (moved from a motor on the end) for move the slide and (why not) on the slide I want put a “pan” controller…

Why this difference of speed??

I used the slide for making some cool videos, now I wanna convert from a hand slide to an automatized slide…all this for make a milkway hyperlapse…
And I would like use the slide in Horizontal and in Vertical (<- this is the problem!)
Looking on internet there’s some of this ready to buy…but I spend already too much for reflex :roll_eyes:
I can olso use it only in plane, so I can save too much needed torque (I see around youtube too many people use stepper nema 17) The reflex is around 2Kg…And I have alredy to buy the belt and the pulley (I’m waiting to choose the motor)

The maximum speed we can thinking about it…maybe 300mm/s are too much olso, 100mm/s is ok…
When i made a hyperlapse in the night I have to stay in position for shoooting time (20sec) waiting the elaboration time and move of the slide of a certain space

Other problem: MOBILITY when I make hyperlapse I can’t find 230V ac in the top of a mountain…a car battery should be the maximum acceptable…

SO, what you think about it now?

In the end:

Stepper Motor: No good for battery alimentation but I solved all the problem

Servo Motors:I can't command as I want but maybe you can help me? I don't undestand how to say to a servo make 3,5 turns

Dc motor with gear: I need to add encoder, speed gestur ecc...

Eeeh...I don't know the torque I need..I'm here for this :roll_eyes:

Well, we don't have your machine.

Primer on force and torque here. You can measure the force required to move something with a simple spring or luggage scale.

Thank you jremington

If I undestand my request torque is 50Nmm

Because:

F=(m*g)*pulley radius

F=(2*9.81)*2.5

F=50Ncm

I don't take in consideration the friction, it shold be 0,65 olso if I use lubrification and it should be 0,11

We don't have to considerate the inertia?

I would measure the force needed with a bit of string and a pan to which I can add weights until there is enough to cause movement. It will take account of friction and will probably be accurate enough for motor selection.

…R

I don't understand your calculation, or the units of measurement.

I want move horizontally or vertically 2Kg of things

Horizontal motion and vertical motion are two completely different scenarios, and have to be treated differently.

Robin2's suggestion for measurement is good, although you will probably need a pulley for the string.

Can I use a dinamometer for take a measure…but from Kg how can I find Nmm?
Tomorrow I try

Here we are!!!

From the test I made I need 50Ncm for the horizontal movement and 100Nm for vertical moviment

Yesterday I was thinking about the fuction of the slider...

For delete all the problem I prefer a slowly maximu speed but a better precision, for delete the battery problem I would use a dc motor geared with an encoder like this http://www.avagotech.com/products/motion-control-encoders/magnetic-encoders/aeat-601bf06

But now the question....where I can find a dc geared motor maybe with encoder??

Thank you

100 Nm??

Sorry the mistake, 100Ncm

But the vertical movimenti I will never use I think…I prefer have a stable horizontal and fully regolabe horizontal moviment :smiley:

But now the question....where I can find a dc geared motor maybe with encoder??

Well, if you ask Aunt Google for "DC motor geared 1 Nm" -> you will get thousands of hits where to buy.

It's now up to you to decide for: - gear ratio - max. force (add about 20-30% to the 0,5 Nm to be on the safe side) - voltage - max RPM

to find the right motor for your application.