UMO+ stange stretched prints in z-direction / z-axis issue / layers larger than set?

[dscheyh 0]

I experience a very strange behavior: prints are getting "strechted" in z-direction. It looks like the z-axis is moving downwards more than wished / defined. Printer is UMO+. I used Cura 3.4.1, layer height was set to 0.2 mm. Actually in the past few weeks I had often prints with not bonding layers. I assume this is related to the z-axis issue. I have never seen or experienced such an issue in now 6+ years experience with UMO printers. Any ideas what the root-cause could be and how to fix it would be very much appreciated. Or anyone else with the same problem?

 

In the image you see on the left the desired print result of a phone case from an UM2+, on the right the same print with same settings on the UMO+.

 

 

 

[gr5 2,172]

Well steps/mm is probably set wrong.  Did you update the firmware on the UMO recently?  Some versions of Marlin have a "motions settings" menu somewhere in there and you can view and set steps/mm.  Fix that value by moving the bed 100mm and measuring how far it actually moves and dividing the difference and correcting the steps/mm of the Z axis by that value.

 

If you did update the firmware maybe you have UMO firmware on a UMO+?  They have different Z steps/mm I think.  Often you have to do "factory reset" to load all the defaults of the new firmware properly (loading new firmware sometimes messes up all the eeprom saved settings).

 

You have the white circuit board, right?  There is a jumper near the center of the board that can affect steps/mm by 2X.  If that is loose and jiggling that could cause it to occasionally step 2x but this seems very unlikely.

[dscheyh 0]

Many thanks gr5 for your feedback. I have not updated the firmare of my UMO recently. Also I had not seen that issue in the past.

 

I have made some slicing tests with Cura 3.4.1. and compared with 3.3.1 when slicing for UMO (incl. heatbed) and for UM2+. Very interesting results which may show an issue in the slicer in Cura 3.4.1. Below you'll see the calculated slicing times which are odd for the UMO in v. 3.4.1 as they differ by almost 80-100% for an UMO vs. the time for an UMO2+:

 

Example STL 1:

Cura 3.4.1: on UMO: 3:18h on UM2+: 1:41h

Cura 3.3.1: on UMO: 1:59h on UM2+: 2:08h

 

Example STL 2:

Cura 3.4.1: on UMO: 5:08h on UM2+: 3:02h

Cura 3.3.1: on UMO: 2:58h on UM2+: 2:14h

[dscheyh 0]

-- Issue solved ---

 

I found the root-cause in the z-steps/mm settings on my Ultimaker Original with original heatbed (use the Ulticontroller Control > Motion)

 

- old: +0200.0

- new: +400.1

 

I have saved the settings then via Control > Save or store memory. 

 

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