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Z axsis

Posted by Andico 
Z axsis
January 21, 2023 12:06PM
Hallo guys,

I have a problem with the Z-axsis of my machine and I hope someone can help me. I have noticed that the machine loses steps and it happens only for the Z-axsis both when going up and down.
Z-axsis remains stuck while the motors try to raise it up.
I have attached a video of a little test I've done. In particular, I find setting the righ first-layer height impossible and the next layers come up poorly as a consequence.
Might It be anything to do with the acceleration?
open | download - video5938420636140440592.mp4 (1.79 MB)
Re: Z axsis
January 21, 2023 01:23PM
You have two steppers lifting the X axis. Every time you power up the machine, the motors jump. There's no guarantee that they will jump the same amount or the same direction, and they end up tilting the X axis. When it tilts far enough, the mechanism starts to bind and you lose steps. The fix is to readjust the X axis so it is perpendicular to the Z axis, relevel the bed, and in the future, relevel the X axis each time the machine is powered up. The simplest way is to set mechanical stops at the top of the Z axis so that when the X axis is up against both stops it is perpendicular to the Z axis guide rails. If there's 200mm to the mechanical stops on the Z axis, send it to Z=205mm. That will force both ends of the X axis against the stops and ensure that X and Z are perpendicular. Then you can drop Z back down to 0.

An even better fix is to drive both Z axis screws from a single motor with a looped belt. That way the two screws will always stay in sync and the X axis will not tilt relative to the z axis and the bed.

Edited 1 time(s). Last edit at 01/21/2023 02:46PM by the_digital_dentist.

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Z axsis
January 23, 2023 03:36AM
I am attempting to reposition the endstop on the upper portion of my machine, as previously suggested. Specifically, I would like the machine to perform a homing sequence along the x-y axes and move towards the top portion of the machine along the z-axis. After the homing sequence is complete, I would like the machine to set the coordinates X=0, Y=0, and Z= the height of my printer. I am currently encountering difficulty in writing the necessary firmware, and I would greatly appreciate any guidance or suggestions you may have in regards to this matter. In particular, the machine is moving towards the upper portion of the machine as intended, but the endstop appears to not be functioning properly as the machine continues to move upward despite the endstop being activated.
Re: Z axsis
January 23, 2023 02:13PM
The endstop (the electronic switch) goes at Z=0. If you're trying to square the X axis by running it up to the top of the Z axis, you don't want an endstop (the electrical switch) at the top of the Z axis. The endstop will stop it from moving when it is triggered. You want the X axis to hit the mechanical stops at both ends of the Z axis, so if the mechanical stops are at 200mm, send the extruder to Z=205 mm. You can reduce motor current when you do to ensure that you don't damage anything by trying to drive past the mechanical stops. You will have to set the maximum Z value in the config file(s) to 205 mm (as an example- use whatever value makes sense on your machine).

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