Stepper Motor Troubleshooting

Do they still misbehave when they have a mechanically resistive load?  How many wires attach to your motors?

Yes they misbehave with a load, though they more often than not just sit still. They are 4 wire motors, 2 phase, 48 N/cm holding torque, and possibly take 1.8 amps. They are sold by Mixshop, where I got my kit, but they don't have much more info than this.

Okay, that is a bi-polar motor, bi-phasic steppers that are unipolar have 5, 6 or 8 wires.  Describe your driver, please.  You need either a bipolar supply, or an H-driver architecture driver.  You have two coils, we need to be able to push and pull on both of them.  In the appropriate sequence.  I believe Hitachi developed a 5-phase motor and driver that needed to be driven in a pentagram path that were less prone to resonance.  I don't think these caught on very well, shame.  You have a (quadrature) four-phase, two coil motor.  If you have only ever been able to take a step or two at best, you are probably mistakenly using a unipolar driver on a bipolar motor.  2phase +0- would have three main terminals for the power, four output connections, and four power switches.  2phase +- would have two main terminals for power, four output connections (neglecting possible sense channels) and eight power switches.  Your power switches may not be discretes, nowadays..

OK, my motors came in a kit with no documentation on them. All I was told was which wire to put where. The drivers I am using are built into the board. Its a baboi board, which I'm told is basically a RAMPS board and arduino combined. It has four integrated Allegro A4982 drivers. You can find more info on this page; Baboi (Single Electronic Board Solution) - $149.00 CAD : Mixshop 3D Printer, Toronto, Canada, RepRap Prusa Mendel Parts , and http://www.reprap.org/wiki/Baboi, as well as efuntim.com. Whether this is sufficient for my type of motors is beyond me at the moment. Also whether or not I got the right motors is still under investigation.

Okay, that's not it, you have a pair of H drivers, that's the two pin power supply, eight switch case.  So your driver is appropriate.  Are your connections to the motor good?

My connections should be good. I have redone them several times and gotten the same results.

What I do in this situation is to build a dummy stepper motor.  I use power resistors to simulate the coils, I put an led + ballast resistor in shunt with each of these.  Alternatively, I could use light bulbs.  This is how I determine my stepper is getting the right signal.  Thinking about it, you have two coils being energized bidirectionally.  You would need to use two signal diodes, two (different color) LEDs and a ballast resistor for each coil.

What voltage are you powering the motor drivers with?  The board you have contains a chopper drive, which more or less means your driver controls how much current can be delivered to the motors regardless of the motor voltage.  The major benefit is that you can apply higher voltages, which improve the step response of your motors.  What I suspect is that you are running the motors too fast for the voltage you are providing.  Likewise if you are micro-stepping, the motor could be spazzing out, from the torque load.  Stepper torque outputs I believe exponentially decrease with the number of micro-steps.  Last bit, when you transition from stop to start, or direction changes etc.  you need to ramp the motor up to speed.  If you are simply telling the motor to move full speed from a dead stop, you are going to have these kinds of issues.

A current-source driver is typically less prone to resonance (spazzing out) than other types.  Micro-stepping is just using a sinuate stimulus rather than a square one and tends to diminish (rather profoundly, typically) the chance of resonance.  Yeah, if the current is turned down too low, it will just click or make other sounds.  Once, AF contaminated the signal of my driver and the stepping motor made a so-so speaker!  The way to get this guy to work if it is hooked up properly is to make sure there is the right amt of current, the motors are spected in terms of potential, but what really matters is current, start with nominal motor voltage / coil resistance.  Mechanical loading affects resonance as well, try and have at least a little bit of friction in your load and not too much inertia.  For some situations, micro-strepping isn't the answer because the motor won't stay exactly in place if it is depowered.  TM is right to suggest going slowly at first.

If you have a dual-trace scope (recording is best) your drive signals would be digitized sin and cosine waves, if you kept going the same direction.  You could drive the horizontal axis with one and make a brick-like lissajous figure.  You can make your scope probes into current probes by putting a small resistance across them.  Measuring the potential across the coils and inferring current is the next best thing.

I like TMs idea that you just may not have the current turned up high enough.

Two kinds of torque in a stepping motor, drive torque and detent torque.

'Chopper drive' means a current-source drive that is swichmode.  The CS driver is intended to minimize the effect of coil inductance.  Your motor coil has resistance and inductive reactance.  The coil is ill-wont to allow changes in the current going through it.  It sources its own potential to oppose attempts to change this current.  Current source drive introduces a super voltage during the initial moment to overcome (establish the new magnetic field) the reactive component of the load more quickly.  CS drivers are less sensitive to loading vagaries.

Stepper motors at rest detent at the full steps.  If the rotor is intended to remain at rest in a micro-step, the ratio of the currents in the coils have to be maintained, but they can be mutually diminished.  This is the other side of chopper drive.

It is sorta fun to adjust the current from an insufficient to a tenable range.  The motor clicks helplessly then get's it together, it's rather like watching a toddler rise from the floor.

There was an interesting developmental pathway to these apotheosis off-the-shelf CS-chopper drives, which will soon, properly be lost to history.  In the early days, an external resistor was associated with each coil and the potential souped-up.  A common setup with industrial-grade printers was a 12V driving a 5V stepping motor with resistors 7/5s as large as the motor coil resistances.  The next step (neglecting nxQ schemes) was activating (cascode) the loads, but it took awhile to develop a current source circuit that was both modulatable and fast.  I've drawn the circuit that broke the logjam in another post.  Kids today!  You don't know how good ya' got it!

I should note that, even if you just drive your motors detent-to-detent 'micro-stepping' is really sweet because it takes lotsa unwanted high-derivative mechanical energy from the system as regards square-wave drive.  The motor runs quieter, everything is smoother, less whiny.