# What's the "W" mean? (Stepper motor terminology) **URL:** \ **Category:** Factual Questions\ **Created:** [January 6, 2017, 4:27am UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444 "2017-01-06T04:27:17Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 6, 2017, 4:27am UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/1 "2017-01-06T04:27:17Z")
OK, I understand how stepper motors work, and how microstepping works. But, I can’t figure out what the “W” is supposed to stand for in the “Excitation Mode” terminology: Microstep Resolution Excitation Mode Full Step 2 Phase Half Step 1-2 Phase Quarter Step W1-2 Phase Eighth Step 2W1-2 Phase Sixteenth Step 4W1-2 Phase ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [January 6, 2017, 5:06am UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/2 "2017-01-06T05:06:09Z")
Winding ? ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [January 6, 2017, 5:33am UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/3 "2017-01-06T05:33:10Z")
> [@beowulff](#): > > OK, I understand how stepper motors work, and how microstepping works. > But, I can’t figure out what the “W” is supposed to stand for in the “Excitation Mode” terminology: > > Microstep Resolution Excitation Mode > Full Step 2 Phase > Half Step 1-2 Phase > Quarter Step W1-2 Phase > Eighth Step 2W1-2 Phase > Sixteenth Step 4W1-2 Phase W=Wave (Drive) mode. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 6, 2017, 1:40pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/4 "2017-01-06T13:40:14Z")
> [@ZurBob](#): > > W=Wave (Drive) mode. Ahh… that makes sense. I looked on every data sheet I could find, and none of them defined that terminology before they used it. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [January 6, 2017, 5:25pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/5 "2017-01-06T17:25:23Z")
Honestly: My IIRC failed me on this one, and ended up digging through my old notes. My work on steppers is only occasional, and usually involves only twisting the wires in a _like kind_ replacement. Most of the “knowledge” is held within our AB PLCs that I rarely need to modify. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 6, 2017, 5:36pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/6 "2017-01-06T17:36:00Z")
Decades ago I picked up a used equatorial mount solar tracker. It had a 120VAC electric motor driving it, and I replaced it with a surplus stepper-driven worm-gear reducer, and a breadboarded stepper controller. When I dusted it off (literally), I hooked it up to a power supply and tested it, and it worked perfectly, but it had more vibration than I was comfortable with, so I decided to re-do the stepper driver from 1/2 step to 1/16 step. I needed to figure out the gear ratio and step frequency (since I didn’t keep any notes from the first time). Turns out that the worm-gear reducer is 100:1, and the final gear reduction on the mount is 60:1, giving a final reduction of 6,000:1, or 19,200,000 microsteps/revolution. I’ve ordered driver boards from ebay and ICs from DigiKey (1.000MHZ crystal and a Divide-by-N counter (set to divide by 1,125)). It will be interesting to see if the 1/16 step is that much smoother than the 1/2 step I’m using now. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [January 6, 2017, 6:25pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/7 "2017-01-06T18:25:00Z")
Sounds like there may be some overkill in resolution (19,200,000 microsteps/revolution) for a solar tracker. This could lead to _more_ vibration/chatter depending on the hysteresis of the controller. Another thought: Is the motor capable of 1/16 step… Some are, some are not. Just a notion: Perhaps _reducing_ the resolution may eliminate the problem. Go from 1/2 to 1; 1 to 1 1/2, etc., instead of the other way around. Sometimes, “looser” control parameters are key to a system’s operability. Good luck with your project! ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 6, 2017, 6:33pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/8 "2017-01-06T18:33:30Z")
> [@ZurBob](#): > > Sounds like there may be some overkill in resolution (19,200,000 microsteps/revolution) for a solar tracker. This could lead to _more_ vibration/chatter depending on the hysteresis of the controller. > > Another thought: Is the motor capable of 1/16 step… Some are, some are not. > > Just a notion: Perhaps _reducing_ the resolution may eliminate the problem. Go from 1/2 to 1; 1 to 1 1/2, etc., instead of the other way around. > Sometimes, “looser” control parameters are key to a system’s operability. > Good luck with your project! The nice thing about the controller I bought is that they can be set to 1, 1/2, 1/4, 1/8, or 1/16 step with jumpers, so I can test different modes on-the-fly. I’m going to put some lead weights on the camera/lens system, which should help damp out any vibration. With a 6,000:1 gear ratio, I figure the motor should have no problem turning 10 lbs! ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [January 6, 2017, 7:01pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/9 "2017-01-06T19:01:11Z")
> [@beowulff](#): > > The nice thing about the controller I bought is that they can be set to 1, 1/2, 1/4, 1/8, or 1/16 step with jumpers, so I can test different modes on-the-fly. Out of sheer nosiness, would you PM me a link for your controller? ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [January 6, 2017, 7:53pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/10 "2017-01-06T19:53:03Z")
Thanks. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 22, 2017, 3:43am UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/11 "2017-01-22T03:43:35Z")
So, I got one of the controllers in the mail the other day. This one is interesting - it implements a sine-wave interpolation between each microstep, resulting in 256 interpolated microsteps per full step. I breadboarded it, and connected it to the stepper motor, and the resulting motion is a smooth as an[Android’s bottom](https://www.youtube.com/watch?v=DXPaZzUP5wk). It’s based on the TMC-2100 IC. [Here’s](http://www.ebay.com/itm/Anycubic-3D-Printer-StepStick-TMC2100-stepper-motor-driver-with-sink-excellent-/272313645376?hash=item3f67287940:g:xuIAAOSwayZXjzWH) the one I bought. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [January 22, 2017, 12:01pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/12 "2017-01-22T12:01:40Z")
Glad it worked out so well. The minimal cost blows my mind. I received a 3-D printer for Xmass… Sooner or later, I may travel the same road you are on. May your tracker always achieve the optimal angle toward the Sun! ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 22, 2017, 3:20pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/13 "2017-01-22T15:20:39Z")
> [@ZurBob](#): > > Glad it worked out so well. The minimal cost blows my mind. > I received a 3-D printer for Xmass… Sooner or later, I may travel the same road you are on. > > May your tracker always achieve the optimal angle toward the Sun! Ooohh… 3D Printer! Have fun with that toy! And, yes - there is a ton of info on the web about using this particular driver with 3D printers. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [June 12, 2017, 10:32pm UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/14 "2017-06-12T22:32:10Z")
Bumping this in the unlikely event that anyone cares - The TMC-2100 board I bought drives the stepper motor so smoothly in “stealthchop” mode that I can’t detect any vibration at all - even using a screwdriver on the motor stuck in my ear, it is completely silent. My divide-by-n circuit also works great. I even put a switch in for Sidereal vs Solar tracking (not that it would really make andy difference, but what the heck). ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [June 13, 2017, 11:06am UTC](https://boards.straightdope.com/t/whats-the-w-mean-stepper-motor-terminology/776444/15 "2017-06-13T11:06:01Z")
> [@beowulff](#): > > Bumping this in the unlikely event that anyone cares - > > The TMC-2100 board I bought drives the stepper motor so smoothly in “stealthchop” mode that I can’t detect any vibration at all - even using a screwdriver on the motor stuck in my ear, it is completely silent. My divide-by-n circuit also works great. I even put a switch in for Sidereal vs Solar tracking (not that it would really make andy difference, but what the heck). Very interesting! Thanks for the update.