Z Banding, Bent Z Screw?

New Home Forum Mostly Printed CNC – MPCNC Troubleshooting – MPCNC Z Banding, Bent Z Screw?

This topic contains 3 replies, has 2 voices, and was last updated by Profile photo of Robert Robert 3 weeks, 4 days ago.

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  • #32775
    Profile photo of Robert
    Robert
    Participant

    I’m decently bad banding in the z direction. The spacing of the bands lines up perfectly with the leadscrew, so I’m thinking it has to be related. I think the leadscrew is slightly bent and is causing the extruder to wobble once per revolution. Has anyone else experienced this? Is there a good way to fix it (I could maybe find a way to straighten the rod)? Most of my printing is structural, and since this is mostly a cosmetic flaw, I don’t care too much.

    Banding

    From the sticky:
    1) I bought all the hardware here. The parts were printed on a friend’s machine out of PETG (yeah, at the time I didn’t realize PETG was this flexible, and it’s probably part of the issue here).

    2) Yes, I’m using endstops. No, I don’t think that’s the issue

    3) PC

    4) Here’s a picture. As you can see, I have an odd setup here. I’m using this as a combo printer and router. When using it as a router, my spoilboard is mounted on top of this box, reducing my z travel to 4″ and vastly improving rigidity (and looks really cool without the exposed electronics). When I want to print, I take the spoil board off to reveal my heated be and get a whole 8″ of travel.

    My Setup

    Overall, I’m super happy with this machine. I even made some cuts in aluminum and it worked surprisingly well! (I was able to do it at 6mm depth thanks to Fusion 360’s adaptive clearing. Video and post to come later)

    • This topic was modified 3 weeks, 4 days ago by Profile photo of Robert Robert.
    #32777
    Profile photo of Robert
    Robert
    Participant

    I’m decently bad banding in the z direction. The spacing of the bands lines up perfectly with the leadscrew, so I’m thinking it has to be related. I think the leadscrew is slightly bent and is causing the extruder to wobble once per revolution. Has anyone else experienced this? Is there a good way to fix it (I could maybe find a way to straighten the rod)? Most of my printing is structural, and since this is mostly a cosmetic flaw, I don’t care too much.

    IMG_20170503_211346

    From the sticky:
    1) I bought all the hardware here. The parts were printed on a friend’s machine out of PETG (yeah, at the time I didn’t realize PETG was this flexible, and it’s probably part of the issue here).
    2) Yes, I’m using endstops. No, I don’t think that’s the issue
    3) PC
    4) Here’s a picture. As you can see, I have an odd setup here. I’m using this as a combo printer and router. When using it as a router, my spoilboard is mounted on top of this box, reducing my z travel to 4″ and vastly improving rigidity (and looks really cool without the exposed electronics). When I want to print, I take the spoil board off to reveal my heated be and get a whole 8″ of travel.

    Overall, I’m super happy with this machine. I even made some cuts in aluminum and it worked surprisingly well! (I was able to do it at 6mm depth thanks to Fusion 360’s adaptive clearing. Video and post to come later)

    IMG_20170503_211619

    • This reply was modified 3 weeks, 4 days ago by Profile photo of Robert Robert.
    • This reply was modified 3 weeks, 4 days ago by Profile photo of Robert Robert.
    #32785
    Profile photo of Ryan
    Ryan
    Keymaster

    Could be a bent rod, or it could be crooked in your coupler.

    The other thing is one side is always more true than the other. I ship them as they should be used. I spin them in a drill. I send them with the coupler nuts on the end that should be down and the other end should go into the coupler. I am sure you don’t remember how I shipped it so you might want to take it out and chuck it in a drill and find which end spins more true.

    I get the highest grade my supplier offers before stainless steel and test spin and run the nuts up and down each one. You should have a true end.

    1 user thanked author for this post.
    #32793
    Profile photo of Robert
    Robert
    Participant

    Thank you. I’ll flip it around tonight and see if that solves the problem. You’re correct, I didn’t pay any attention to where the nut was on my screw, so there’s a 50% chance I installed it the wrong way.

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