Odd behavior on Z driver using both Za and Zb



  • Hi

    I ordered by Duet in September and recently started the setup. I've been testing each subsystem successfully until now. So far, my X and Y motors work as do all of my end-stops, fans, hotends, heated bed.

    My Z, however, is problematic. I've tested each cable independently to make sure it behaves as expected. When I plug them into ZA and ZB, the Z axis can't move. So, I connected the Za and Zb cables to two free motors and it looks like the motors run in opposite directions!

    In my config, I have the Z driver set to operate backwards. I thought perhaps the driver configuration was wrong and only operating on Za so I set it to forwards, at least hoping the two would run in the same direction. While the direction did change, it changed for both motors (so they are still going in the wrong direction).

    My first thought would have been mis-wired connections but, again, I've tested these independently. Also, I'm taking my time with each cable, checking connections under a lit magnifying glass, wringing them out with a multi-meter, etc.

    Thanks
    Jack



  • What motors? Photo of wiring going into motor?

    I connected the Za and Zb cables to two free motors and it looks like the motors run in opposite directions!

    You can physically reverse a 4 wire stepper by swapping the coils. If the wires are 1234 at the board connector right now, swap pairs to make them 3412.

    And you can verify coil pairs at any time via:

    1. Spin the motor with your fingers and get a "feel" for how it spins.

    2. Short two wires. Literally just pinch them together with your finger. Spin the motor again. Did the "feel" change? If so, this is a coil pair. If not, keep swapping wires. The effect is not subtle; you'll know it when you find it.



  • @jrwaters2 said in Odd behavior on Z driver using both Za and Zb:

    So, I connected the Za and Zb cables to two free motors and it looks like the motors run in opposite directions!

    I recently had the same issue with that driver. You are most likely going to need to do what @Danal suggests and reverse the rotation of one of the steppers by swapping the coils physically with a wiring change.

    In my config, I have the Z driver set to operate backwards. I thought perhaps the driver configuration was wrong and only operating on Za so I set it to forwards, at least hoping the two would run in the same direction.

    The firmware does not see Za and Zb as separate. There is only one driver associated with both of those physical connections, so changing the motor direction in the config file will change the output for both of those connections. Again, it will be necessary to change the wiring of the coils physically to get both motors to move in the direction you want.



  • @Red-Sand-Robot - thank you. I am out of town all week and will try reversing the wires next Saturday. I will also post a picture when back in town. I appreciate your help.



  • This post is deleted!


  • @Danal thank you. I've used a multi-meter to verify the coil pairs. All of my motors are Nema 17. I'm pretty sure of the wiring because I tested each set of wires on the X axis.



  • @Red-Sand-Robot I've attached the image you requested. Its a Nima 17 motor. I'm going to try reversing the motor today as well.

    JW note: since deleted this picture as I think it was too large and consumed the limit for the thread or something. Anyway, picture didn't show much of interest. A nema 17 motor with 4-wire cable.



  • I haven't had much success. I visually inspected my Duet3d and noticed that a couple of the pins on one of the motor headers are not soldered and push through when the connector gets plugged in. Sigh. If I were skilled with a soldering iron I'm sure it would be fixable but I'm a software guy. Does anyone know how to get warranty support from Duet?



  • @jrwaters2 said in Odd behavior on Z driver using both Za and Zb:

    Does anyone know how to get warranty support from Duet?

    Where and when was it purchased?



  • @Phaedrux September 6th from Matter Hackers.



  • Might be a good idea to contact them as well.



  • @Phaedrux thank you. I’ll do that.

    Best
    Jack


  • administrators

    @jrwaters2 said in Odd behavior on Z driver using both Za and Zb:

    I haven't had much success. I visually inspected my Duet3d and noticed that a couple of the pins on one of the motor headers are not soldered and push through when the connector gets plugged in. Sigh. If I were skilled with a soldering iron I'm sure it would be fixable but I'm a software guy. Does anyone know how to get warranty support from Duet?

    Can you post a photo showing the unsoldered connections? Also please let us know the serial number printed on the label on top of the microcontroller, so that we can determine which of our assembly companies made that Duet.



  • Hi @dc42

    I have attached the image. The pins are in the lower side and they are protruding. My serial number is W01255. The label says "DUET2 MAIN W01255". Thank you for the help.

    ![0_1574658285680_IMG_9247 (1).jpg](Uploading 100%)



  • @dc42 odd - The image preview doesn't show. I get "ERROR - something went wrong while parsing server response.". If you provide an e-mail address I can mail it as well.


  • administrators

    @jrwaters2 said in Odd behavior on Z driver using both Za and Zb:

    @dc42 odd - The image preview doesn't show. I get "ERROR - something went wrong while parsing server response.". If you provide an e-mail address I can mail it as well.

    My guess it that it's too large to be accepted as an upload. Can you host it on Dropbox or Google drive and link to it? Or email it to info at duet3d dot com.



  • Thanks @dc42. Tried lots of sizes that are all much smaller than the picture I uploaded a few days ago. I did just mail two images to the address you stated with a subject line of "Pictures for forum topic 12945 (https://forum.duet3d.com/topic/12945)".

    Jack


  • administrators

    Thanks for the pictures, we'll take this up with our assemblers. If you have not already done so, please contact MatterHackers for a replacement. If they ask for authorisation, refer them to this post.



  • Thanks all for the help here. Great community and great support from Duet.


  • administrators

    PS - any chance you can send us a better photo of the badly-soldered pins first? When taking close ups with a smartphone, I find it best to pull the camera away from the board until the focus is sharp, then use the digital zoom.


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