Intentinally run motors into hard limits

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This topic contains 11 replies, has 5 voices, and was last updated by  Ned van Geffen 6 days, 4 hours ago.

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  • #102651

    kd2018
    Participant

    Would it do any damage to the motors, electronics, or anything to intentionally run tandem motors into hard limits, letting them “chatter” and miss steps for a moment, in order to square things up?

    What if the standard nema 17s were running at closer to 1.7 to 2 amps ?

    • This topic was modified 1 week, 5 days ago by  kd2018.
    #102655

    Erwin Vigilia
    Participant

    Wow, this is like banging my head against the wall to stop the voices… just kidding, This Old Tony is rubbing off.

    If the stepper drivers are set up properly, most have overcurrent/overtemp protection built in – which would only help if your motors are capable of sinking the overcurrent safely. More likely to break something mechanically before your blow up a stepper motor or driver.

    #102656

    kd2018
    Participant

    Wow, this is like banging my head against the wall to stop the voices…

    Gotta do what you gotta do

    #102665

    Jamie
    Participant

    The torque is low enough, and the parts generally strong enough, that skipping steps on X or Y won’t damage anything.  The risk is all mechanical, there’s no real chance of hurting electronics or motors.

    The Z axis has more opportunity for damage because of the gear ratio, but even then I have accidentally crashed and lost steps without any apparent damage.

    I wouldn’t recommend this strategy for squaring, but that’s a separate discussion.

    #102666

    kd2018
    Participant

    I wouldn’t recommend this strategy for squaring, but that’s a separate discussion.

    No, that is the discussion! Please discuss!

     

    #102667

    Erwin Vigilia
    Participant

    No, that is the discussion! Please discuss!

    Implement dual endstops and you’re done, auto square FTW!! 🙂

     

    1 user thanked author for this post.
    #102669

    kd2018
    Participant

    Dual hard endstop semi-autosquare.

    • This reply was modified 1 week, 5 days ago by  kd2018.
    #102690

    Jamie
    Participant

    There are some additional thoughts on this topic here: https://www.v1engineering.com/forum/topic/speculation-how-to-rip-off-ideas-from-the-pros/

    1 user thanked author for this post.
    #102695

    Aaron
    Participant

    The Prusa MK2S uses the minirambo, and to square up the Z axis, you have to run the  axis into the upper hard stops. it’ll be fine for a short amount of time.

    #103056

    Ned van Geffen
    Participant

    they only do that because they have TMC2130 steppers that detect when they hit the end, and that is their end stop… They dont run them and keep driving into them for any length of time

    #103069

    Aaron
    Participant

    they only do that because they have TMC2130 steppers that detect when they hit the end, and that is their end stop… They dont run them and keep driving into them for any length of time

    MK2S has A4988 because it uses the rambo mini 1.3, like the one that is sold for the mpcnc.

     

    If you do the z calibration on the prusa it tells you to rotate the knob. When you rotate the knob on the lcd, it turns the z steppers and moves it upwards, and you have to move it up until both side hit the stops. It takes less than a second to square it up if you use hard stops on the mpcnc. I did it that way on my mpcnc for 8 months straight before every job, and I had 4-8 jobs 5 days a week.

    • This reply was modified 1 week ago by  Aaron.
    #103145

    Ned van Geffen
    Participant

    my bad 🙂

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