A4988 driver help needed

This topic contains 11 replies, has 5 voices, and was last updated by  Curt 10 months, 2 weeks ago.

Viewing 12 posts - 1 through 12 (of 12 total)
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  • #77174

    Curt
    Participant

    I built my MP3DP out of spare parts I had from other projects.  One key difference I have is I am using A4988 stepper drivers.  I read through everything I could locate on the Ramps 1.4 and the A4988 drivers and all I did was get more confused.  I made the edits to the firmware change from the DRV8825 to the A4988 but something is still not right.  Do I still use all three jumpers or do I use less?  Or can I make a change in Marlin to correct things?  I am trying to print a small 3/4″ end cap and the printer starts to print a MUCH larger circle

    #77182

    Ryan
    Keymaster

    You should be using all three jumpers and only need to change the steps per mm in the firmware to half of what they currently are.

    #77204

    Dui, ni shuo de dui
    Participant

    I’d recommend to go for 1/16th step, so only one jumper.

    1/32th step doesn’t bring anything in terms of actual real life precision, lowers the torque and also lowers the possible speeds a lot. I used to have all my machines set to 1/32, but after I changed to 1/16th I don’t think I could ever go back.

    #77207

    Raphael
    Participant

    I’d recommend to go for 1/16th step, so only one jumper.

    1/32th step doesn’t bring anything in terms of actual real life precision, lowers the torque and also lowers the possible speeds a lot. I used to have all my machines set to 1/32, but after I changed to 1/16th I don’t think I could ever go back.

    Hey Dui, I think you have something mixed up, all three jumpers are 1/16th step with A4988 drivers 🙂

    Unbenannt
    A4988 is not capable of 1/32.

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    #77302

    Dui, ni shuo de dui
    Participant

    Oh, sorry, I thought you were having the DRV8825, my apologies!

    I got mixed up, indeed

    #77310

    Curt
    Participant

    So if I change from

    #define DEFAULT_AXIS_STEPS_PER_UNIT { 200, 200, 800, 200 }

    to

    #define DEFAULT_AXIS_STEPS_PER_UNIT { 100, 100, 400, 100 }

    things should work?

    #77321

    Ryan
    Keymaster

    Should, super easy to test, manually move it 10mm with repetier and make sure it moves 10mm. If it does not let us know exact what it moves.

    #77734

    Curt
    Participant

    You all are great! I was finally able to get back to the printer after getting all my Christmas lights going.  I was able to get the printer and the quality is GREAT!  The issue I am having is the steppers are noisy.  They vibrate or buzz and I am wondering if this is caused by the vref not being set right on my a4988 drivers?  Any suggestions?

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    #77775

    Ryan
    Keymaster

    Set your drivers for 70-80 your steppers max amp rating and that will be about as quiet as they get. Some of the imports do buzz for some reason, it does not seem to a a functional problem but some are more noisy than others.

    #77970

    J Smith
    Participant

    I have this set up, not quite finalized yet but getting close. The thing I noticed is the x axis vibrating a lot, making an annoying noise. I tested stuff and it’s definitively not coming from the steppers. Something is causing the horizontal steel rods to vibrate, it’s really annoying. If I apply some pressure on them with my hand, it cuts down the vibration by half. The 2 screws holding them in are as I tight as I dare them to be, don’t know what else I could do to minimize the sound.

    #77988

    Ryan
    Keymaster

    J, I am unclear to what you are referring. It would be best to start a new thread and maybe add some pictures of what you built and what you are using.

    #78033

    Curt
    Participant

    I ended up increasing my vref to 1.0 and most of the vibration disappeared

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