Stepper motor and driver problem

Other Hardware General Electronics
1

Hi All,

I have a little project with an Arduino and stepper that I use for astronomy. I use this exact set up on multiple devices and many others use the exact set up successfully too.

Now, i’m currently assisting a gentlemen in the states to set it up but i’m having some issues and hoping the forum can assist.

some info about his set up.
sketch: my sketch no issues on 12+ other projects.
Wiring: from video calls i’ve had with him everything is wired correctly.
Arduino Uno - temporary for his first prototype.
stepper: TB6600
motor:

  • Motor Type: Bipolar Stepper
  • Step Angle: 0.035 deg.
  • Holding Torque: 4Nm
  • Rated Current/phase: 1.68A
  • Phase Resistance: 1.65ohms
    power supply to driver :12V

Issue:
Motor vibrates but does not turn, but it is the testing that’s interesting. please see below different combinations and results.

tb6600 set to 2 amps and 32 micro steps and motor connected

  • motor does not turn
  • voltage measured at power input is showing 8.6 volts instead of 12 volts.

tb6600 set to 2 amps and 32 micro steps but the motor is disconnected

  • voltage measured at power input is correct 12 volts.

tb6600 set to 0.5 amps and 32 micro steps and motor connected

  • voltage measured at power input is correct 12 volts.

is there a reason the voltage drops when the motor is connected at 2 amps also happens at 1.5 amps, should this be happening? Also interesting to note voltage stays correct when tb6600 set to 0.5 amps.

The stepper has to step extremely slow so we did some further testing at the extremely slow speed and higher speed to see if there was a difference.
slow speed: 1 step every 22471 micro seconds
fast speed: 1 step every 224 microseconds.

tb6600 set to 0.5 amps and 32 micro steps motor running at slow speed.

  • motor vibrates but doe not turn

tb6600 set to 0.5 amps and 32 micro steps motor running at FAST speed.
-Motor turns fine!

So in summary we can get the motor to turn fine when TB6600 set to 0.5 amps and 32 micro steps running at FAST speed. There is no other combination of amps or microsteps that makes the motor turn.

I hope this information is enough.

In summary, why is the voltage dropping to 8.6 when tb6600 is set to 1.5 amps or higher and motor connected, is this normal?

why will the motor only turn when set to 0.5 amps and a quicker speed?

thanks for your help.

2

Schematic? Not asking for code now, as you say it works elsewhere, but a schematic might illuminate a common problem or weak point. Hard to sort wheat from chaff in several paragraphs of text.
Photo of installation?
First guess, grounding issue. Trace ground to all power supplies and boards, make sure none are loose or missing.

3

Sorry, please see attached.

Pin 13 grounded is due to us just trying to get motor working before using pin 13 for a push button. Easier to get him to ground than change sketch.

Also not sure if he has the capacitor as per notes.. waiting for his reply.

PXL_20230225_100930157
PXL_20230225_1009301571920×1446 89.7 KB

4

So this exact arrangement works elsewhere? And that pin 13 to ground is your only difference? Makes me suspicious that your code may not deal with a continuous low the same way as a momentary pushbutton. Code posting, please, to rule that out.

5

But your voltage drop may point to a poor power supply connection, too. Or, small gauge wire from PS to TB6600.
Just guessing, really. Code may not be required, can't imagine a scenario where code activity could pull down the PS.
When the PS drops, does th buck converter output remain stable?

6

I think he is using small guage wire from power supply to driver from memory. I'll have to go back through photos he has sent.

Is there any possibility of a damaged motor?

I know he fried an Arduino board by accidentally connecting the push button to 12v instead of 5v. Hence why I've told him not to use push buttons at this point. Could pushing 12v through Arduino pin 13 have also damaged the motor?

7

No it is easier to get him to just leave it not connected as during upload of a program to the Arduino the LED on pin 13 flashes. So you are connecting a pin which is an output that can be high to ground. A great way to destroy at least that pin and maybe the Arduino.

Yes just like putting 12V putting any Arduino pin can damage it. However we don't know what the circuit was for controlling the motor. I assume you have a motor driver and that motor driver could well have been damaged. So the motor drive rather than the motor would be damaged.

8

Hi, @greggles91

What exact power supply is being used?
It sounds like the 12V power supply is a 1A unit rather than a 2A or more.

Has the stateside user connected the two negative, input and output terminals together.

Are you sure the stepper pin out wires colours/pairs are correct?
Get the user to use a DMM and measure resistances to identify the windings.

Can you get an image(s) of the project so we can see the component layout?

Thanks.. Tom.. :smiley: :+1: :coffee: :australia:

9

BLDC motors (not sure how close they are to steppers) that I have seen hum with no movement have been due to wires touching or sensors loose. Wires can be the internal windings or external phase or feedback. Loose hall effect position sensors might make the motor try to catch up or slow down (1000s times a minute).

10

0.035 degrees per step would be 10285.7 steps per revolution. Is that some kind of gear motor? If so, what is the motor's steps per rev, and EXACT gear ratio? What is the power supply's current capability?
What is the RPM of "slow speed"?
Post your code.

11

Hi,
Have you sent some test code, JUST to get the stepper operating?

Why have you got pin 13 going to gnd?

Tom.. :smiley: :+1: :coffee: :australia: