Wiring Q: Japan Servo Co. Stepper

[Thomasio]

I'm retofitting a new controller on a rotary tool changer on a small CNC lathe. There is currently a Japan Servo CO. KH56QM2-801 stepper motor. 1.8 degrees per step, 3.15 volts.

The strange thing is that there are six wires, but only four are used. It is a uni-polar stepper, with the following six wires:

Red (used)
Black (not used)
White/Red (used
Green (used)
White (not used)
White/Green (used)

The stepper motor calls for this excitation sequence (which obviously can't be done if the Black wire and the White wire aren't used:

Step: 1 2 3 4
red : - -
grn : - -
w/r : - -
w/g : - -
b : + + + +
w : + + + +

So these are my two quesions:

One: why is it being run without using either the black (b) or the white (w) wires?

Two: what controller can I use to run the stepper? (I will be using Mach 3 Turn... it would be cool to have tool changing capability, but worst-case I would be okay with manually advancing the tools using a simple controller and a button)

Thanks for your help!

[doorknob]

The excitation sequence that you have shown is intended for use with a unipolar driver that uses all 6 wires of the motor.

You can hook up a 6-wire motor using only 4 wires and connect it to a bipolar driver. There are two different ways to hook it up using 4 of the six wires - either in "half-coil" or "full-coil" mode.

See Support Figures 9 and 10 for a better explanation.

From your description, it sounds like it is set up for the full-coil hookup (the winding center taps are not connected).

[Thomasio]

Thanks for that information. Is it less expensive to control as a bi-polar setup? Can anyone recommend a controller?

[stewi]

In principle unipolar setup is less expensive than bi-polar. In practice, only printers and scanners use the cost advantage of a lower cost driver IC.
With Mach3 you are restricted to the use of the printer port, however, you can use a low cost 3-axis driver board from China (ebay) or more sophisticated Gecko driver, which is recommended by this site.
I could not verify your part number. Is it 901 or indeed 801?

[Thomasio]

In principle unipolar setup is less expensive than bi-polar. In practice, only printers and scanners use the cost advantage of a lower cost driver IC.
With Mach3 you are restricted to the use of the printer port, however, you can use a low cost 3-axis driver board from China (ebay) or more sophisticated Gecko driver, which is recommended by this site.
I could not verify your part number. Is it 901 or indeed 801?

I'm definitely going to use Geckos (as in my 3 axis mill / servos).

I'm 99% sure it is the 801... the tag was a bit soiled but that appears to be it.

[stewi]

KH39GM2-801 pdf, KH39GM2-801 description, KH39GM2-801 datasheets, KH39GM2-801 view ::: ALLDATASHEET :::