z axis

This topic contains 4 replies, has 3 voices, and was last updated by Profile photo of Dui, ni shuo de dui Dui, ni shuo de dui 1 week, 3 days ago.

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  • #33632
    Profile photo of Ed
    Ed
    Participant

    I’ve been building a MP3DP and I am having trouble with the Z axis moving twice as much as it should. I am having trouble finding what lines I need to edit in the firmware. Any help would be greatly appreciated

    #33634
    Profile photo of Jeffeb3
    Jeffeb3
    Participant

    Either your “steps per mm” are off, or you’ve got the jumpers configured for 16 microsteps. You should have all three jumpers installed for 32 microsteps.

    The steps per mm is in the config.h (or is it configuration.h). There’s one for x, y, and z. If you search for steps it shouldn’t take long to find it. It should be close to 800 (not 400). IIRC, it’s either 800 or 788. It says something like that on the MP3DP page.

    Also, you can adjust the steps per mm in the LCD settings, but you need to save the settings or you’ll lose them after a power cycle. And then you’ll lose them again when you flash new firmware.

    Post a pic of your printer. It sounds like you’ve made good progress!

    #33641
    Profile photo of Ed
    Ed
    Participant

    Thanks for the fast reply. That’s kind of what I was thinking.

    I was having trouble with the z and E steppers stalling. When I started with the 88245 they would stall out so I am guess I need to adjust the pot and /or turn down the accel.
    What I had done was changed my stepper driver to a 4988 from the DRV8824. Come to find out the 4988 only supports up to 1/16 micro stepping.

    I will post a picture soon as I can. It is a total mess at the moment with wires going everywhere and my cobbled together print bed.

    #33648
    Profile photo of Jeffeb3
    Jeffeb3
    Participant

    You definitely need to adjust or at least measure the pot, unless you bought them from vicious. But be careful you don’t short something. If they are set too low, you’ll skip steps. If they are too high, they could burn up the motor or the driver.

    #33661

    Your motors were probably stalling because you were trying to move them too fast.
    Try again at 1/32 step (put all the jumpers on the RAMPS board) and lower the speed, it should work.

    Then you should be able to increase the speed until you find what is the maximum speed on your machine. Once done, take 80% of this value (to keep a safe margin) and use it in your slicer as your maximum machine speed.

    You can also try to use it at 1/16th step if you need more speed, I’m not sure 1/32 step really makes a big difference in terms of quality (but surely Ryan knows much more than me about that, since I haven’t actually tried it yet)

    No need to touch your potentiometers at this point, except if you have set them up to crazy values, in which case, reset them to the standard value. Potentiometers should only be adjusted once all the rest is done, to increase slightly your torque, decrease heat, or decrease noise.

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