No Response From Stepper
February 04, 2014 05:18PM
Hey guys,

I'm a university student as part of a group project to build a granule extruder 3D printer, but I am completely new to the wonderful worlds of 3D printing, arduinos and electronics.

Right now I'm developing the electronics for our project, but my problem is that I just can't get the NEMA 17 bipolar stepper motor to rotate/hum/anything. We are prototyping our granule extruder soon and for this we will only require the motion of a single motor to turn the extrusion screw. So what I've been trying to do is simply get this motor running!

The set up

I have an Arduino Mega 2560 hooked up to a RAMPS 1.4 board. I have installed a single Pololu A4988 stepper driver upon the RAMPS board as shown:

I have a 12VDC power supply as shown, which I found from a scrap inventory area in my department. I have tested it with a multimeter and it reads 12.24V and all is believed to be in working order:

I have attached the 2.1mm DC connector to the Arduino below. I'm a little worried that this power supply, although it seems to be sufficient for the one required motor, isn't all that I need. I've seen many setups that use the 11A and 5A power connections on the RAMPS board, so my first question is is this power supply sufficient for my needs or have I overlooked something?:

Moving on, I have attached the motor as follows. The second following picture shows the order of the wires that I am using if you cannot see clearly in the first following picture. I presume this is correctly done:


I have been uploading the RAMPSTestCode.pde into Arduino 1.0 to run the test (I'm using 1.0 instead of a later version because it seems to be more compatible with the Sprinter firmware). When I connect the motor up to the RAMPS board (before I have turned on any power to avoid any possibility of frying), and then turn on the juice simply nothing happens. And I really don't know where to go from here!

If anybody could help me out I would be very, very grateful!

Many thanks in advance,

Re: No Response From Stepper
February 04, 2014 05:35PM
For basic testing without an extruder heater (D10) or a heated bed (D8), 2.1A will be fine.

That said, the stepper drivers need power on the 5A input, else they won't work. The DC barrel jack will ONLY power the Arduino. It's a good test of the Arduino though, but it won't help with testing motors.

If you're only driving 1 stepper at a time, you should be able to use the 2.1A supply to test. For a real printer setup, you will need a more powerful supply.

PS: Make sure you always turn the power off and disconnect it before disconnecting/connecting motors. This will avoid accidentally damaging the stepper drivers.
Re: No Response From Stepper
February 04, 2014 06:02PM
Right I see! Thank you very much for clearing that up!

So if I purchase a power supply with at least 16A that provides 12V I should be good to go? Any suggestions about which to avoid and which are preferred? A quick google search suggests an ATX power supply so if not I'll head in that direction.

Many thanks!

Re: No Response From Stepper
February 05, 2014 02:00AM
An ATX supply works well. I'd suggest a little bit more than 16A (eg: 20A), as some PSU's tend to lie slightly about their capabilities.

Specifically, they may be able to do their rated current for very short periods, but not for long extended ones, which may be the case with a print job.
Re: No Response From Stepper
February 05, 2014 04:31PM

Thanks Cefiar you've been a great help! smileys with beer

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