[Darc]

I'm looking to purchase a driver for this stepper motor, I emailed the company for the electrical diagram but they won't email me back.
Can anyone help me with bot the wiring and possibly recommending a drive?
I was hoping I could just use a Gecko or a CNC Teknix.

I need the motor to move quite slowly, I will be cutting off small bars of steel, then retract away.
On that note "What is the difference between Bi Polar & Uni polar"?

[rodmdx]

Hi Darc

all steppers motors info are on many site i have beeen downloading
infomation on steppers motors and driver cards for the past 5 years
it is hard to understand them all but to understand them you need to make the time to download and read all info on them you will soon understand how they work i have built driver boards using the parts from an old dot maxtrix printer using transisters and other parts and tracing the Circuit on the board
it is fun

[n2cnc]

Darc,
It looks like the stepper has 4 different windings (8 wires 2 per winding)
It could also be 2 center tapped windings with 2 ground leads.
To figure it out get an Ohm meter and a pad of paper and writing implement.
Draw a grid with 8 columns and rows Like a checker board pick a labeling system for the wires say the black wire as 1, tan as 2 green 3 yellow as 4 etc. does not mater just pick one you like. Now label the rows and columns in the grid 1 to 8.
Starting with wire one measure the resistance to each of the other wires use the lowest ohm setting on your meter. The values will be low. If there is no connection put a dash in the box. Note the value measured between each pair of wires in each box where you measured conduction.
You will only have to fill in half the grid in a triangular section. Measure the resistance between the case of the motor and each wire note that value in the diagonal line. Any wires that had conduction to the case are ground wires and should not be connected to any of the other wires or your drive circuit. If you have 4 independant phases the wires that have conduction to each other are the winding leads. The resistances between each pair will be about the same value. You will either connect a pair of them in series or parallel before hooking them up to your driver circuit. Different connections will work better or worse depending on how they are phased. One way to firgure it out is to get a small power supply or 1.5 volt Battery With the powersuppy set at a volt or so hook up one pair of leads to the battery. Measure the torque to turn the motor. Hook up a second pair with the first. Does the torque increase or decrease?
If it decreased reverse the leads on the second pair. Is it higher now or lower? If it is higher one way than the other than that is the correct phasing between those two windings. If their is no difference between either arrangement than that pair should not be wired on the same driver circuit. Do the same with the other phases It should become obvious which ones provide the best combination. The other method would be to apply power to the next phase and see how far the motor turns. You want to pair up the phases in shuch a way that the motor does not move or moves the least.


If you have 2 center tapped windings you will have three wire sets that have conduction. The wire that has the lowest value between the other two will be the center tap. The other two wires of the three will be the leads you would use for powering the motor in a bipolar configuration.

Hope this helps.

Ron

[Darc]

Hi n2cnc,
Thanks for the descriptive response, I'll give that a go when I get time, I'm thinking you've done this before.
Here's a few more pics of the wiring inside the motor, I thought this may assist in working it out.
I was thinking of seding all these pice to Gecko to see if they could suggest and supply a drive to suit.

[xyz100]

Here is another way of figuring it out. Assuming you figured out wiring for each winding as n2cnc described. Now you should get a bi-polar stepper driver. Connect one winding to one phase and one of remaining three to another. Try to drive it.

If stepper does not move it means that the second winding belongs to the same phase as the first one. Proceed to defining polarity (below).

If stepper does move it means that the second winding belongs to the second phase. Using same technique check remaining two windings while keeping first winding as it was connected.

Defining polarity. At this point you know which two windings belong to phase 1 and which other two to phase 2.

Connect one winding of the stepper's phase #1 to the driver board. Connect one of the winding of the stepper's phase #2 to the driver board. Drive the board and notice the direction. Replace stepper's phase #2 winding with another remaining phase #2 winding. Drive the stepper and notice the direction. If it is opposite swap the phase #2 winding connection to the board. Now it should rotate in the same direction. Now you know everithing about phase #2. Using same techique cheeck phase #1.

As of driver board recommendation. 8-wire steppers usually can be wired either as uni-polar steppers or bi-polar steppers. If you want to get max torque it is recommended to wire it as bi-polar with windings of each phase wired in parallel. The torque will be roughly 40% higher. Another benefit is it can operate at lower voltages. The negative of bi-polar steppers is higher cost of the driver board (H-bridge is required). Either way it is your call.

PS: for the tests described above you will need bi-polar driver board! Good luck.

[trungsy]

Your Motor is permanent magnet Bifilar Motors.
Bifilar windings on a stepping motor are applied to the same rotor and stator geometry as a bipolar motor, but instead of winding each coil in the stator with a single wire, two wires are wound in parallel with each other. As a result, the motor has 8 wires, not four.

In practice, motors with bifilar windings are always powered as either unipolar or bipolar motors. Figure 1.4 shows the alternative connections to the windings of such a motor.

Figure 1.4 : http://i72.photobucket.com/albums/i1...thanthep/4.gif
To use a bifilar motor as a unipolar motor, the two wires of each winding are connected in series and the point of connection is used as a center-tap. Winding 1 in Figure 1.4 is shown connected this way.

To use a bifilar motor as a bipolar motor, the two wires of each winding are connected either in parallel or in series. Winding 2 in Figure 1.4 is shown with a parallel connection; this allows low voltage high-current operation. Winding 1 in Figure 1.4 is shown with a series connection; if the center tap is ignored, this allows operation at a higher voltage and lower current than would be used with the windings in parallel.

It should be noted that essentially all 6-wire motors sold for bipolar use are actually wound using bifilar windings, so that the external connection that serves as a center tap is actually connected as shown for winding 1 in Figure 1.4. Naturally, therefore, any unipolar motor may be used as a bipolar motor at twice the rated voltage and half the rated current as is given on the nameplate.

The question of the correct operating voltage for a bipolar motor run as a unipolar motor, or for a bifilar motor with the motor windings in series is not as trivial as it might first appear. There are three issues: The current carrying capacity of the wire, cooling the motor, and avoiding driving the motor's magnetic circuits into saturation. Thermal considerations suggest that, if the windings are wired in series, the voltage should only be raised by the square root of 2. The magnetic field in the motor depends on the number of ampere turns; when the two half-windings are run in series, the number of turns is doubled, but because a well-designed motor has magnetic circuits that are close to saturation when the motor is run at its rated voltage and current, increasing the number of ampere-turns does not make the field any stronger. Therefore, when a motor is run with the two half-windings in series, the current should be halved in order to avoid saturation; or, in other words, the voltage across the motor winding should be the same as it was.

For those who salvage old motors, finding an 8-wire motor poses a challenge! Which of the 8 wires is which? It is not hard to figure this out using an ohm meter, an AC volt meter, and a low voltage AC source. First, use the ohm meter to identify the motor leads that are connected to each other through the motor windings. Then, connect a low-voltage AC source to one of these windings. The AC voltage should be below the advertised operating voltage of the motor; voltages under 1 volt are recommended. The geometry of the magnetic circuits of the motor guarantees that the two wires of a bifilar winding will be strongly coupled for AC signals, while there should be almost no coupling to the other two wires. Therefore, probing with an AC volt meter should disclose which of the other three windings is paired to the winding under power.

[studysession]

Thanks -
I need to read another time or two to make sure I fully understand. But I think I follow what you are saying. Thanks again.

[Darc]

Thanks for your help guys, I did as you suggested, and I attached a pic of the results.
When I used a 1volt battery on 5&6 it was quite strong, I then used it on 7&8 and it was also quite strong, I then put a 1 volt on both 5&6 and 7&8 and the torque required to turn it increased.
I reversed one of the battereys , but I didn't notice any difference in holding power.
I connected 1volt up to any of the other terminals but it didn't achieve anything, so are they still used in the same manner.
Because I would like to use this motor as a cut off machine, it will need to move quite slowly.
I've gotta say I was impressed with how strong it is with just 1v attached.
Any idea how I work out what voltage I will need?

[trungsy]

You can send an email to ORIENTAL MOTOR Co.ltd to have the detail information which you need.