3 Wire / 2 Phase Stepper in my Rotary Needs to be Reversed

Please, can someone help me understand what I’m looking at?

I set out to reverse the coil pairs on my rotary and was confronted with a very strange surprise. My 2 phase stepper motor only has three wires coming out of it.

I scratch my head and search everywhere trying to figure out the right way to reverse the direction / wiring.

I’ve applied a volt meter to the pins. I’ve read resistance. I’ve read voltage (while turning the chuck). No matter what two pins I measure, values are always the same.

I figured if the coils were in series… I’d get half / double reading depending on the pins and then I’d be able to determine how they were wired. Nope.

When Using Rotary, Must I Always Rotate 90 and Mirror?

If you are getting equal resistances between each possible combination, then it sounds like a 3 phase motor not a typical 2 phase stepper.

Swap any 2 of the 3 leads should reverse it.

Hank. That is EXACTLY what I have convinced myself of as well (especially considering that my Y stepper motor is 3 phase and the rotary borrows that same driver - a Yako YKD3505M 3 Phase Stepper Driver). But then I am hit with the only specifications I can find for this motor:

I’m just going to go for it!

Well that’s interesting. If it was 2-phase with the 2 windings tied together, then one would expect to find one combination of wires with double the resistance of the other 2.

It’s also interesting to note that the tag on the side of the motor in that photo says “0.3A-4A” and the text below says “0.4A - 2A” so there’s already reason to wonder what other info may be incorrect.

Just for fun, what was the resistance you got between each pair?

Well, I can’t remember. However none of that matters now. I just swapped position of two of the wires on the connector and tested it. It works exactly as expected, and now I don’t have to mirror my image in LB when using the rotary.

Testing on a scrap stainless bottle:

I also just fine tuned my rotary parameters to 7800 from 10000 steps per rotation. Now everything on the rotary is tuned in very well!

And would you believe that a CO2 laser could do this to stainless? :sunglasses:

@Stroonzo

Is that order for the CDC to isolate the nasty bug we all love to hate so much… :rofl: :sneezing_face:?

What wattage CO2?

144.7w when running at 28mA (100%). That was 70% at 5 inches /sec.

Some other steel playing around:

Tempered steel:

Plain carbon steel:

that’s good to know, I didn’t know a CO2 laser would mark SS without using something like Ceramark

Oh yes. It’s a specific alloy that does very well.