Micro Stepping Issue

I am having a problem with MicroStepping my stepper motors.. I took a video.. watch for yourself, and tell me what you think the problem might be.

Stepper Motor Details:
MFG: SHINANO
P/N: STH-39G120
NEMA: 16
COIL: 1.2 ohm
TYPE: 2 Phase Uni-Polar 6 lead
3.6 Degree step angle. 5mm dia. X 9mm serrated steel shaft. 4 M3X 0.5 metric mounting holes. 4" leads.
SQ.: 1-1/2” L: 1-1/4” WT: .36

That's all the info I have regarding these stepper motors... sadly..

These are the Driver Boards I got:
http://www.amazon.com/dp/B00E7O5O8I/

They are set to 1/16 Micro Stepping Mode, however, I get the same issue in 1/4 and 1/8 mode.


Here's the video showing the problem:
http://youtu.be/oFSmAZPV9Ds

See [hydraraptor.blogspot.co.uk]

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[www.hydraraptor.blogspot.com]

R4 is already a 0 Ohm Resistor.. what do I do in that case?

Hard to say from video but i think i counted like 10-15 jumps for something that looked to me like a 90 degree angle. Compare to motor steps per rev. Hard for me to see but maybe you can count the jumps and approximate a more accurate number of jumps for a 90/360 degree and compare it to motor specs. Just to be sure it is indeed a microstep issue.

It was indeed a 90 degree angle. I can hear the "clicks" inside the motor, however, the motors seem to resist the micro-stepping.

Yes but what i meant was that visually for my eyes, one "jump" does not equal one step. Where one step is per motor specification 1.8 degree or 0.9 degree. To me, one of those "jumps" look way more than that. In which case, a "jump" seem to contain more steps, not just one. Following that logic, perhaps its not a microstep issue at all, perhaps something to do with firmware acceleration across multiple steps, where firmware starts to accelerate then somehow decides to slow down by itself. Just speculation, maybe i see it wrong.

It's not a firmware issue, as I already checked that,

This stepper motor is 3.6 degree step angle, so it has a larger stride than most motors.
This motor so I was told, was custom made for IBM.

Aha ok so in that case a 90 degree angle would be like 90/3.6 counting 25 jumps, if makes 25 jumps then seems right.
I see your motor is unipolar 6 wires, so have you tried using only half of coils instead of full coils. Although that probably wont help as motor resistance is already kind of low. Cant read the voltage on that supply but if its too low like 5v or so maybe current wont reach the correct values in due time, that could be fixed with an atx 12v psu supply. If it does that with 12v supply maybe the coil resistance is more than 1.2 ohms, you can double check that because custom motors dont follow datasheet, so different specifications for that motor its not out of the question.

It is a 6-wire, but I have it wired as BiPolar.
I have checked the resistance, and it's aprox. 1.3 Ohms per coil.
I have not tried running it half-coil yet.. Should I?
The LiPo battery I am using is 11.1 Volts.

Any other suggestions?

If it is 1.3ohms per coil then i think using half coils probably wont help. I was thinking maybe if it was like 8-9 ohms then half coils could of made bigger difference.
Then imho try change the battery to a atx psu. The battery is ideal power source only on paper, in practice it has internal resistance, and the stepper puts it on short circuit. Also the resistance is just a simplistic review, for the custom motor try check the inductance, if its higher than normal value for this resistance, that could be a reason for the behaviour. If all else failed to sove the problem, maybe try changing the motor, in case you have some other motor to do this test with.

how did you get the 1/16 micro stepping mode ? will you please explain ? I want to do microstepping for my nema 17 motor

any help, much appreciated !!

Quote
Dr. Bogger

They are set to 1/16 Micro Stepping Mode, however, I get the same issue in 1/4 and 1/8 mode.

how to set 1/16 micro stepping mode ? please help !!

You set the jumpers under the polulu modules, most boards this is jumpers, some boards this is software... depends on what board you have.

Eg for ramps see the colored jumpers below



Set as desired following this table


High == jumper on.

@Dust thanks for sharing this information. I really appreciate it !! as i'm new to this area, i don't know how to make these jumpers ON (high). If you have any information, any video link please share it thanks

[wiki.shapercube.com]

If a jumper is in place covering and shorting out the two metal pins, the signal is set to be high.
If the jumper is missing, ie you just have two metal pins the signal is set to be low.

Eg the image above is set High, High, Low, and if you look at the table above that that is Eight stepping.