need help with stepper motor

[CNC Darren]

hi all i bought 4 of these motors a while back for a foam cutter and want to get back to finishing it once my CNCrouter is done. But I am having a heck of a time figuring out the wiring on them as i'm still a newbie to this. They are 5 wire unipolar. Here is a pic of one, the Applied Motion home page doesnt seem to list them but that doesnt really surprise me as the mfg date is 7-83.

Darren

[MrBean]

Find the common centre tap with a multimeter and apply +12V to it. Now take any other wire and ground it, call this #2, now pick another wire and ground it as well, if the motor moves clockwise label it #3, if counter-clockwise label it #1. If it does not move label it #4 (or the motor is knackered). Remove the newly labeled wire from ground, still leave the other two connected (+12 & #2)

Pick another unlabeled wire and repeat the above steps untill all wires are labeled.

The wire numbers are not important, it's the sequence that is.


Hope this helps.

[High Seas]

Mr Bean! What a nice tutorial for labeling the wires. Now, I suppose you picked 12Volts - as thats what the motor was rated at? Is there any "margin of safety" that we can use for "unknown motors"? Eg if it "might" be 5 volts would 12Volts be too much? Seems like when running steppers everyone runs over volts - but watches current closely. Would the same apply to this testing scheme? Cheers and Thanks - Jim

[MrBean]

Thanks. I didn't think it was worded very well. Hopefully it makes enough sense to be usefull.

Use the motors rated voltage. No need for higher voltages as there's no load on the motor and it not rotating. It's only moving one position in half step mode to determine the "firing order".

If you use a higher than rated voltage and it's not current limited, the motor will make smoke, especially if it's not in continious rotation.

If ratings for the motor are unknown. Start with a low voltage, only hold the wires on for the minimum time it takes to see if there is a CW/CCW move. (test more than one wire in case you picked #2 & #4 on the first go, as you'll see no movement) . If you still see no movement, move to a higher voltage, or the motor is a dud.

I don't know how much overvoltage you could apply to a stationary stepper before it smokes. Not too much I expect, that's why they have ratings.

[CNC Darren]

the common center tap will have the same resistance across all the wires correct?

[CNC Darren]

ok i think i have it. Now i assume that #1,2 would be step and #3,4 would be direction?

[Ferenczyg]

No. The steppers have no wires for step and direction. In purity, all are 'step' except the common. The *rigth sequence* of steps define a direction. The procedure of MrBean only defines a rigth sequence from where you choose your first wire.

[CNC Darren]

hmm ok, I have all my wires numbered here is a pic of my board. SO A=1 a=2 b=3 B=4? and the com would be the center tap?