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Problem with steppers

Posted by lucek 
Problem with steppers
September 11, 2017 04:28AM
It's my first topic so Hello to everybody smiling smiley

I have a problem with steppers in my Prusa I3 - steppers acting strange, goes back and forth or just vibrating. You can see that in videos: x axis, x axis. On both axis I run homing with pronterface and on X axis I click '+10' several times. When I do that it goes on both sides although I click to go only one side.
Steppers are Nema 17 - 17HS2408, step 1.8*, 0.6A, set to 16 microsteps (all 3 jumpers)
Stepsticks are A4988, RAMPS 1.4, Arduino Mega, RepRap discount smart controller.
Firmware is Marlin 1.1.5

I check stepsticks and steppers on other arduino duemilanove and I manage to turn stepper both directions with a simple sketch from this article.
Functions non related to steppers (endstops, heating, temperatures) is working.
My configuration:
#define DEFAULT_AXIS_STEPS_PER_UNIT   {80,80,4000,600} 
#define DEFAULT_MAX_FEEDRATE          {500, 500, 2, 25} 
#define DEFAULT_MAX_ACCELERATION      {2000,2000,20,1000}   
#define DEFAULT_ACCELERATION          3000

I think it's configuration problem, but I don't have experience with stepper motors so I need your help.

Edited 1 time(s). Last edit at 09/11/2017 04:40AM by lucek.
Re: Problem with steppers
September 11, 2017 08:05PM
Your numbers look ok, with slipping like that I would normally expect the feedrate to be too high.

Before you put the belts on did the carriages (for X and Y) move smoothly? Was their any binding? (I dont think this is the cause but is always good to check first as its easy to fix). Also check the tension on the belts.

I think your problem might be with the current on the A4988. They have an adjustable resister that can change the current. I think you might have it set too high. Take a multimeter and with the board on check the current and adjust as needed. Be carfle when adjusting as you can short the stepper driver, best to adjust with the bard of then turn back on to check what the new current is.

Link on motor current and adjusting [reprap.org]
Re: Problem with steppers
September 11, 2017 09:46PM
17HS2408 are really small... you probably have to reduce max feeds rates alot to use them.
Re: Problem with steppers
September 12, 2017 12:42AM
Good pick Dust, I just saw Nema17 and read on without checking the model number. I'm starting to think if they even have enough toque as are only rated to 12N.cm. I think the weight of each axis will really come into play
Re: Problem with steppers
September 12, 2017 04:19AM
I was thinking about weak steppers, but when belts is off steppers acts the same as with belts on. I order stronger stepper and when it will be delivered I post if it works. In the meantime I try to play with feedrates. Is there any minimum feedrate?
Re: Problem with steppers
September 12, 2017 06:53AM
With belts off it still does it? ok that new info.

That sounds like a wiring issue then (or bad soldering on pololus) , but then how did the other code work?

Check the stepper wiring...
Remove the stepper plug from the controller.
With a multi meter check on the cable plug that there is continuity from pins 1 and 2 and from pins 3 and 4 threw the stepper motor.
Also check there is no continuity from 1 and 3

Also try RAMPS1.4 Test Code
This moves all the steppers back and forth.
NB it also turns on the heaters without looking at temperature, so do not leave unattended

Edited 2 time(s). Last edit at 09/12/2017 07:04AM by Dust.
Re: Problem with steppers
September 12, 2017 11:19AM
I'm really embarrassed smiling smiley
Wiring was wrong, I misunderstood stepstick description and connect first coil to 1A, 2A, and second to 1B, 2B, because coils is described as A, B' etc.
Anyway everything works fine now, steppers don't seem too weak, feedrates is the same as in first post.

Thank you very much for help.
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