Cnc shield and A 4988 stepper driver

i have some questions…i am trying to make cnc machine.i am using a stepper motor.there was no labeling on it.i mean nema 17,nema 14 ,nema 23 or what?..i think this is what i am using…

i am using arduino uno,cnc shild, 2 piece of A 4988 stepper driver,2 piece of stepper motor and a servo motor and 12 v 2 amp adapter.

The problem is after programming and setting up everything motor does not rotates.its just vibrating and giving a annoying sound.First i used 12v 500mA power source.then also motor does not rotated but the sound was little low.then i used 12v 1amp, same thing happened ,but now sound becomes higher.using 12v 2 amp same thing happened and the sound gets ultimate. but the most socking thing is dvd drive motor works perfectly with the same setup… i m fed up with this.

My question is A4988 stepper driver has max current 2 amps, so if i use 10 amp power source will it not harmful for the driver and motor?
i which value i should set the potentiometer to rotate my stepper?


You should use the formula and instructions on the product page to set the current limit on the stepper motor driver. If you are not familiar with how the current limiting on these drivers works, I suggest reading the FAQs on the product page for the stepper motor. If you continue to have problems after setting the current limit, could you post pictures of your setup that show all of your connections and solder joints? Could you also post a link to the specs for your DVD motor?


sorry …i find out my fault. i had a wrong connection in motor its ok.but still i’m facing some problems and regarding the same i have some questions.

At first when i made wrong coil connection the motor was not rotated and gives annoying sound and heat sink of 4988 driver gets hot at 12 v 2 amp power source. But now after correcting the connection motor rotates ,sound is very very low, and heat sink is not getting too hot at same power supply.

But now the Problem is- when i trying to stop the rotor with little pressure (to check if it can pull the x or y axis body) it stops and then the sound gets little higher.

QUESTION 1- Will it resolve by applying higher amperage?

QUESTION 2- suppose after setting everything properly my motor starts rotating normally at 12 v 2 amp…after few days i’ll buy a 12 v 8 amp adapter.then i apply it 12 v 8 amp. will it work normally? i mean if i apply higher amp than required amp will it damage my driver or motor?

QUESTION 3- what is the steps-
Full step,
Half step,
Quarter step,
Eighth step,
Sixteenth step,
and when and why i need to use them?

QUESTION 4- I am using two stepper motor likely this and a servo (model number-SG90).What amperage i should use and in which value i should keep my drivers potentiometer ?


  1. Torque is proportional to current, so increasing current increases the torque. However, your motor is rated for 350mA and trying to draw more than that could damage the stepper motor, so you might be at the limit of the torque you can get from that motor.

  2. A stepper motor driver system like that will only draw the current it needs from a supply. Your 12V supplies will not force current into the system. If you have your current limit set correctly, increasing the amount of current available from the power supply will not be a problem.

  3. The different step modes allow for smaller steps to be taken which in turn allows for greater control and smoother operation. You might find the explanation on this website helpful.

  4. That stepper motor is rated for 0.35A according to its datasheet. You should set the current limit to that according to the instructions in the “Current limiting” section on the product page for the stepper motor driver.