is nema 17 very weak?

I just bought a nema 17 step motor:

I use the a4988 driver with Vmot = 12V@2A.
I just realised that I can easily stop it by almost touching it with my fingers!
How many grams can it lift vertically more or less?

int stp = 4;  //connect pin 13 to step
int dir = 2;  // connect pin 12 to dir
int a = 0;     //  gen counter
int delayTime = 10;

void setup()
{
  pinMode(stp, OUTPUT);
  pinMode(dir, OUTPUT);
}


void loop()
{
  if (a <  2000)  //sweep 200 step in dir 1
  {
    a++;
    digitalWrite(stp, HIGH);

    delay(delayTime);
    digitalWrite(stp, LOW);
    delay(delayTime);
  }
  else
  {
    digitalWrite(dir, HIGH);
    a++;
    digitalWrite(stp, HIGH);
    delay(delayTime);
    digitalWrite(stp, LOW);
    delay(delayTime);

    if (a > 4000)  //sweep 200 in dir 2
    {
      a = 0;
      digitalWrite(dir, LOW);
    }
  }
}

Is there an alternative more powerful step motor?

The motor is rated for 1.5A. Have you adjusted the Vref as described on this page to provide the rated current to the motor?

NEMA 17 specifies the size of the motor mounting plate, nothing else.

It is absolutely essential to adjust the current limit on the driver, but the A4988 can supply only about 1.2A/winding continuously without extra cooling. You are better off with the DRV8825 driver, which can supply 1.5A/winding, without extra cooling.

if your motor have this big screw as it shows in your picture it make sense because the torque of the motor at greater distance is weaker, but if your motor is without that and you can stop it with your finger u should follow the advices of adjusting the current limiter, becouse this motor can be even use in printers and some small CNC.

the torque of the motor at greater distance is weaker

No, the torque is everywhere the same in a rotating shaft (or lead screw, in this case).

Impressive combo motor/leadscrew thing.
Like a stepper motor f*'d a leadscrew and that is the offspring.

It should have some oomph to it. Maybe you did not set current properly on the driver?

That is my guess, and also everyone else’s. :slight_smile:

These links may be useful

Stepper Motor Basics Simple Stepper Code

...R

I think you have midband-resonance, probably not helped by the undamped mechanical load of the leadscrew. Use x8 or x16 microstepping and see if it cures it.

Undamped stepper motors are really easy to stall. Belt-drive is great for providing damping, and leadscrews much less so (unless a really tight fit on the nut).

Hi people, really thanks for your quick responses. Well, it my first stepper application and I was not sure what's going on. I tried all possible power configuration of the driver and I didn't get any extra power. Even at 100% of the pot, with 12V/2A power supply the power of the motor was very low. Perhaps 1.5A is not enough for this leadscrew. Then a friend who has created an arduino CNC came over, and brought some other driver. We connected the TB6560 (3A) instead of a4988 driver and .....voila! The stepper motor was turning strongly and quickly, I had to apply much power to stop it with my fingers. I don't really know what was wrong with a4988, it could be that I didn't manage to configure it properly. Perhaps it was a faulty part. The heat sink would never get warm or something. I wanted to ask, its tiny trimpot, how many rounds does it make? Because of the heatsink I can only turn it only ~340 degrees, almost a full circle. I have also ordered a DRV8825 driver to see if it goes any better. I will post back with the testing results

If you buy modules like motor drivers, sensors or MCUs cheap on eBay, expect failures.

You may have blown the driver - its very important to never hot-plug the motor to a driver, securely connect motor windings before applying power, as the motor is a very inductive load and loose connections lead to arcing and damage. But it could have been a knock-off - not uncommon for fake chips or production line rejects to appear on eBay, a real curse in fact. The A4988 is also not powerful enough for 1.5A. The DRV8825 is just about able to handle that.

fatecasino: Even at 100% of the pot,

You can't adjust the pot by percent. The maximum rotation position is not the maximum current that the driver can provide. You must use the technique shown by the manufacturer, where you measure the voltage while turning the pot.

And yes, never plug or unplug any of the stepper motor wires while the driver has power. That will destroy it instantly.

You can find some information about how to adjust the current of an A4988 or DRV8825 here.