Dual Y - Mirror drive 1 to drive 4?

  • I’m looking to use dual Y motors and want to use the unused driver 4/extruder 1. I know marlin firmware has this feature, so I’m hoping to do the same with Duet. I know I can run them on same driver in series or parallel, but the amps are too high.

    Thanks in advance!

  • Yup, you simply tell the firmware what they are assigned to in the M584 command in the config.g file.

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    On My FT-5 which has dual Y motors I put them in the Z axis output then put the original twin Z axis motors into the Y axis & E1 outputs this allowed my i utilize the new bed leveling feature by separating the Z axis motors on to each having its own driver.

    Hi CaLviNx, have you tested the bed levelling yet? I haven't had any feedback on how well it works with just 2 Z motors yet.

  • side note, on my FT5 the left side lead screw moves very easily. When I turn off the power, i can see it drop up to 10mm on the left side. My work around for now is to eyeball level the bed before power on. This gets it close enough for mesh leveling to work. I am thinking of setting a box under the bed after i power off to make it fall level instead of just 1 side. I am still waiting on parts to convert to single z motor. I have decent 2 amp motors so doubt power will be an issue. I am pretty much convinced the z motors in series is not a good idea. IMHO they do not always move equally. I have matched motors so resistance and voltage drop should be the same but i suspect there is something adding a bit of a voltage drop or delay on 2nd port. no idea why…If the Z mod goes well, I might try to make Y a single motor too. I am an old fart so always look for a hardware solution over a software fix. 6 one way or half dozen the other or am i missing something? 🙂

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    Two Z motors connected in series must move equally provided neither of them skips steps - and if your motors are skipping steps then you have bigger issues to contend with.

    The only significant issue with connecting motors in series is that the combination needs double the voltage of a single motor. Typical motors used in 3D printers need about 3V at low speeds, so this is not normally a problem. It could be a problem under either of the following circumstances:

    1. You are using high voltage, high inductance, low current motors. I know that Folgertech used to use 12V 0.4A motors in some of their delta printers. Later they changed to a more sensible choice of motor. I don't know what they use in the FT-5.

    2. If your Z axis uses a fine-pitch threaded rod then you will have a high steps/mm and will need to run the motors at high speeds, which increases the voltage needed. However, if one of your motors drops 10mm when you power off, this can't be the case for your printer, I think it must be using course-pitch leadscrews.

  • And I would suggest that the one that isn't dropping is binding somewhere?

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    If they are rated at 1.5A then the voltage drop won't be very high.

  • Thanks for the replies. I don’t even have my controller yet. Moving from ramps, I have a lot to learn.

  • A bit of topic but not too far IMO:

    How about connecting 4 motors on a single (external) driver? To maintain the needed voltage same, would it work connecting 2 pairs in series and then those pairs parallel?

    Just poundering the simplest way to make my bed move with 4 motors.

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