Unipolar Headaches: An Irritated newb

So i have put together my printer. I have the board wired and jumpered and the firmware, although unmodified from it's original configuration, installed.
I can activate the printer with Pronterface, but that's were it becomes apparent that something is up.

The motors don't turn really turn. They mostly hum and vibrate. I don't know the exact cause and this is why:

They do actually turn a bit, and I've been conscious of the fact that these motors are not ideal from day one.

I'm still a little unconfident in my wiring.
The motors are 6 pin Unipolar nema 17 motors. On top of just figuring out how to wire up a motor, I had to figure out which pins to exclude. I took apart the extruder motor to look at the windings, which may come to bite me when i get to the point where I'm extruding, but that's tomorrow's fight.

And... in case this helps... The pins on the motors are as follows:
Pin1 is coupled to Pin2 and Pin3
Pin2 -- is a shared center tap--ie not used.
Pin3 is ocupled with Pin1 and Pin3
Pin4 is coupled with Pin5 and Pin6
Pin5 -- shared and not used....
Pin6 is coupled with Pin4 and Pin5

I'm using a ArduinoMega2560 board, with the board shield. the board came with push clips that are wired to correspond to the following pins:
Red 2B
Black 2A
Blue 1A
Purple 1B

The wiring diagram I was using, and that I assumed was made specifically for the kit, showed that red should correspond to Pin1 on the stepper motor, and the other colors would naturally follow the order they appear in the push clip. (This puts Pin1 to red, Pin3 to Black, Pin4 to blue, and Pin6 to Purple).

Even with all that lining up, I thought I still might have done the wiring wrong so i did take it apart and tried excluding Pin3, and Pin4 instead of pin2 and pin5, but that had worse results (didn't hum or spin).

After rewiring, I figured that the problem might be in the amount of current that's getting to the stepper motors. So I very gingerly increased the amount of current going to them. It actually does seem to have helped a little, but now the humming and vibrating is much more pronounced.

So I'm wondering, Is it common to have lots of stepper noise when you're adjusting your RAMPS?

Is there something perhaps wrong in the firmware? The Printer does seem to have inverted it's x and y axis, perhaps the 2a or 2b thing is not right? is there a way to check that? (I use Marlin with LCD support, but it's completely unmodified... i will change that at some point probably.)

Finally.. Is the wiring on the motors wrong? I'm actually kinda skeptical on this last point, since i pulled it apart, I can't possibly see a different configuration, but it is still being weird.

Edited 1 time(s). Last edit at 01/09/2015 02:32PM by Qcks_.

You said pin 5 to purple, but I think you meant pin 6. If so, then your wiring sounds correct to me. Can you post a link to the datasheet for the motors?

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I am still new, so take the following with a grain of salt. However, as far as the ramps board is concerned, I don't think the order of 1A/1B and 2A/2B matters much. You are just completing a circuit and if the motor runs backwards, you can simply turn the plug around.

If I were you, I would use a multi-meter to check the resistance of pins 1/3 and 4/6 on your motor. They should have little to no resistance, indicating a complete circuit. Testing pin 1 against either 4 or 6 should give a resistence of 1 since they aren't wired together in the motor. Then just plug 1/3 into 1A/1B and 4/6 into 2A/2B to test the motors.

Also check your wire crimping, it always seems to be an issue for me.

Finally, use you multi-meter to check the voltage on your motor drivers. I did this by connecting the black lead to the ground on my powersupply, coming into my RAMPS board, and placing the red lead (positive) on my motor drivers potentiameter (which was metal). Start by setting the voltage to 0.4 and increasing as needed...but watch the temperature on the driver IC.

Quote
dc42
You said pin 5 to purple, but I think you meant pin 6. If so, then your wiring sounds correct to me. Can you post a link to the datasheet for the motors?

I did... I'll amend the original post after replying so that it matches.

As for the data sheet... these are kinda the generics that came with the kit. I have a model number, a manufacturer, and I can find a PDF, but it's more like a book then a leaflet.

The model number, manufacturer and listed information that came with the motor:

STP-43D1006
AX050300
1.8"/step
4.7Volts .85Amps
Shinano-Kenshi

The pdf booklet:
[www.shinano.in]

The motor is listed on page 10 of the booklet in the table in the upper left hand side.

Edited 1 time(s). Last edit at 01/09/2015 02:32PM by Qcks_.

I can't find any stepper motors matching that model number in that booklet. There is a list of SST43D motors (rather than STP43D), but there is no 1006 model of those listed either. I did find them listed as 4.7V 0.85A on a Polish web site.

I suggest you measure the resistance of the windings with a multimeter. Also check there is no continuity between pins 1/2/3 and 4/5/6. If the 4.7V 0.85A refers to driving them in unipolar mode, then the full winding resistance will be 2 * (4.7/0.85) ohms = 11 ohms, and they will need about 0.6A @ 7V minimum to drive them at max torque in bipolar mode.

Are you sure that the motors are not mechanically loaded too much, and that you are not trying to drive them to fast? Do they turn if you remove whatever drive belts or gears you have them connected with?

Edited 1 time(s). Last edit at 01/09/2015 05:52PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The labels, where I'm taking the motor information from, might be cataloged according to the people who assembled the kit (DIYtechshop); So I'm not sure if following the part number is the same-same. I followed the motor type, then the voltage and amperage on the sticker. I think the second set of numbers (the AZ stuff) refers to the number of axis coming out of the motor.

That said, I get the same performance with or without load. which kinda sounds like it might be lack of amperage, in which case simply adjusting the RAMPS to allow more amperage through would fix the issue.

I might be trying to drive them too fast. I don't really know what's an appropriate driving speed.

Edited 1 time(s). Last edit at 01/09/2015 06:32PM by Qcks_.

Oh snap.... yeah.. so i probably have 2 issues...

First, the Firmware has a max acceleration of 3000 mm/s2, which would mean, per second squared the motors would be trying to move at least 3 meter.... which doesn't sound reasonable at all....

I turned it down to 30 and now they don't vibrate and hum, they just click and only turn when I demand 10 mm steps or more... Which would be the RAMPS needing to be adjusted up.

It's good that the ramps were turned down, given the frequency they were being driven at.

Is 30 still too high?

30 for the acceleration should be no problem. I use 800 on my Ormerod for X and Y, which does about 87 steps/mm. The Z and the E need to be lower because they have more steps/mm.

Edited 1 time(s). Last edit at 01/10/2015 05:12PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].