Hello all,
I recently came into possession of about 10 floppy drives and decided I would like to use their stepper motors with my Arduino Uno. They all seem to be four pin, bipolar stepper motors. Any advice on shields or other parts I might need to purchase to make something like this work? (The project I have in mind would require at least four of them wired up at once).
bigzam:
Any advice on shields or other parts I might need to purchase to make something like this work?
Yes.
Extremely important: Do not disconnect them from the drive boards.
The drive boards contain all the circuitry you need to control them in a ready-made assembly, complete with connectors. You merely need a PC power supply and its connectors to connect them up.
If you research the FDC interface you will find the details of the control signals which can be fairly directly connected to an Arduino.
Personally, I wouldn't bother with the boards on the floppy drives. These inexpensive motor drivers will work well (avoid the outdated and inefficient L298 drivers). Be sure to follow the instructions for setting the current limit.
You will need a separate power supply for the motors.
Paul__B:
Do not disconnect them from the drive boards.
Ah, that makes things so much simpler! I've played around a bit with SammyIAm's "Moppy," so I already which FD pins do what.
Thanks much!
You may find something useful in stepper motor basics
...R
bigzam:
Ah, that makes things so much simpler! I've played around a bit with SammyIAm's "Moppy," so I already which FD pins do what.
Of course it is simpler.
You mean of course, this Sammy1Am. 
it always amazes me that no one ever discusses applications before recommending hardware.
what do you want to do with them ?
of course you can use the manufactured and designed matching drivers.
or course you can use an outdated and inefficient UNO and drive a modern microstepping stepper driver.
of course you can use an antique like the UNO and drive an antique like an L298
or course you can use a 4 transistors to drive a uni-polar stepper, or 8 and drive a bi-polar one
if you need to run 4 of them, then you really do want to use a driver that has only step and direction inputs.
http://www.ebay.com/itm/191114673825
these take step and input.
Robin2:
That is what stepper motor basics is all about...R
um.... not really.
there is only one sentence about step and direction under that link and no discussion about how to use transistors.
I know full well that steppers is not a subject of basics. well, unless you break down a LOT of basics.
inductors,
resistors
sequencing
power supplies
coil charging calculations
coil discharging calculations
pulse shape discussion ( the unknown key to ultimate motor speed)
pulse speed discussion and how it effects motor speed based on motor steps.....
limits of controller steps (not to be confused with driver steps)
how a stepper 'steps'
how a stepper driver creates the waveforms for each microstep. that is pretty interesting.
the L298 requires 4 steps, as does the motor itself. there is no discussion about that.
what I was getting to was that with 4 motors and each needing 4 outputs, it would tie up 16 pins on the outdated UNO.
I would offer that one could use LED's to visualize the steps, but they are twice as old as the old L298, so they are twice as outdated.
with a step/dir driver one only needs 4 pins to drive 4 motors. or 5 if one would want them to spin in reverse.
that 5 would mean in reverse AND in unison. for each independent reverse, another pin would be needed.
a uni-polar motor has 4 coils. a bi-polar motor has 2 coils.
to operate a uni-polar motor, one has to pulse each coil independently. that means 4 pulses to complete a full cycle.
for the bi-polar, one charges a coil in one direction, then the other coil. then charges the first coil in the opposite direction, then the second coil in the opposite direction. 4 pulses to complete a full cycle.
the power pulses to the motor are from a driver. the logic signals to tell the driver what to do come for a controller.
in this discussion, the UNO is the controller and the A4988 or L298 is the DRIVER.
the A4988 does all that fancy back and forth and such with it's internal circuitry. that means it only needs on pin to signal when to pulse, the internal circuitry knows what has to happen to make the next pulse go to the correct coil in the correct way. one pin, 4 separate things at the motor.
if you want to make the motor go the other way, you just reverse the order of those 4 things.
for the A4988, you chose the second pin, the DIR pin. then the step pulses make the motor go in reverse.
in the L298, the UNO has to use 4 pulses and has to send them out in the correct way.
the exact same thing happens at the motor, but the UNO does less work. and uses fewer pins.
dave-in-nj:
um.... not really.
there is only one sentence about step and direction under that link and no discussion about how to use transistors.
I was particularly referring to your recommendation to use an A4988 - which I fully endorse.
I was also specifically keeping away from transistors, mosfets, etc to keep things basic.
...R
we really do not know the application, so any hardware recommendation is premature.
however, your fine article does give the OP some information to help them make something do something.
dave-in-nj:
what do you want to do with them ?
I suppose I should've mentioned that in my original post! What I want to build is a rubix cube solver. My end goal is to create something that can see the faces of a cube, calculate a solution, and then solve it, but for starters I just want to build something that can hold the cube and let a human solve it by inputting moves for the machine to carry out.
Here is a rough concept of what I was thinking of. The machine would have four claws that could be "on" or "off" (gripping or not gripping). To turn the red face one quarter turn clockwise, all claws would grip and claw 4 would turn 90 degrees clockwise (the claw would then release, return to its vertical position, and grip again). To rotate the entire cube clockwise in that same direction, 2 and 4 would grip and turn, while 1 and 3 would release their grip, allowing enough clearance for the cube's edges to pass freely.
Perhaps the stepper motors present in floppy drives may not be optimal for this project - I just have a lot lying around and thought it might be a way to put them to use.
Though, I do think some sort of stepper motor might be useful for a project like this, as those quarter/half turns would need to be precise.
With this new information in mind, any advice on where to go from here would be greatly appreciated.
I would be surprised if floppy drive motors are poweful enough for manipulating a Rubik's cube.
I would use servos to manage the claws.
I'm pretty sure there was another Thread about a successful Rubik's cube machine. Google should help you find it.
...R