z axis drops

Hello. I have a problem with my printers z axis. Step motor conntected to a 8mm threated rod with a 5 to 8mm coupler. The platform holding the bed moves downward smoothly in first 10mm. After that the platform resists to move for a while then drops 1-2mm to where it should be. The problem repeats in different heights. I have changed the threated rod but the problem persists at the same points. What can i do for that. It ruins my prints. Here is the video of moving platform.



[youtu.be]

Edited 1 time(s). Last edit at 03/15/2018 05:33AM by serdar415.

The nut could be worn out.

It's hard to see from the video, but this sort of behavior is usually caused by misalignment of the bed and guide rails. If the bed binds on one side, the screw will cause it to tilt and it will either bind or the force will reach a point where it springs back to an almost level position and can start moving again. Detach the nut and move the bed up and down manually- it should move smoothly and easily from the top to the bottom. If it doesn't, the guide rails are probably not parallel and need to be adjusted. Hoiw many screws and guide rails are used?

Post a picture of the machine showing the whole Z axis...

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

There are guide rails on each side of an 8mm threaded rod. I removed the threated rod and the platform was still hanging high on the guide rails. It needs a little force to move. How can i adjust their alignments?

Try this- loosen the guide rail mounts at top and bottom. Move the bed to the bottom and tighten the guide rail mounts on the bottom. Now move the bed to the top and tighten the top guide rail mounts. Now try moving the bed up and down without the screw. It should move easily from top to bottom.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I have aligned the z axis rails. The bed moves easly on z axis now. The vibration and sound significantly decreased. However the problem is still going on at the same level. The coupler is wobbling a bit. Can it be responsible?

Edited 1 time(s). Last edit at 03/16/2018 02:51PM by serdar415.

Make sure the grub screws on the coupler hold the screw and motor shaft tightly.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Hello the rod has changed, the coupler has changed and z axis rods aligned and the problem has gone. Thanks for your support.