SOLVED Having weird structural issues with my UMO+

[Allgeuspezl 0]

So I'm having multiple issues with my Ultimaker Original + and I hope maybe someone had simmilar issues and or knows how to fix them.

At first would be the fact that my printer seems to be not capeble of printing round circels even though my little belts are very tight and for the longer ones I've printet tensioners.

https://imgur.com/CdlQM2y

https://imgur.com/jkPe14C

Also I have a problem with these irregular layer lines. They dont look very good especially on slightly sloped parts. Also it does not change with finer layer lines and with long and big prints it kind of disrupts the otherwise good quality of the print.

https://imgur.com/Eu9RcBh

https://imgur.com/96RvySv

Now the worst problem: I dont know what is causing it may it is the software(the newest version of cura)

but I really dont know. It seems to have something to do with the geometry of the print.

https://imgur.com/wQvk41X

https://imgur.com/3CSkpuZ

So I hope someone could help me fix those problems, I mean my other experiences with the UMO+ have been very good. Thank you in Advance.

[gr5 2,230]

Well the first 2 images could be non-perpendicular axes - look straight down from above on the head and see if visually the 2 thin rods that go through the head are perpendicular. Push the head to the 4 sides and make sure the wooden blocks stop the same distance from the sides.

But more likely the problem is play. The last 2 photos are definitely showing play aka backlash (you can look it up in wikipedia as it is a technical term).

On UMO play is usually caused by loose belts (I know you printed tensioners). It can be caused by anything too loose. So gently push the nozzle around without letting the belts move and see how much the head moves. It could be a problem inside the head itself. But usually it's the long belts.

Also paradoxically this can be caused by belts too tight or too much friction. The end caps on the 4 large rods can be too tight making it difficult for the head to move. Push the head around and feel the friction. Clean the rods with cloth or tissue and put one drop of oil on each rod. The two axes should have identical friction and you should be able to move the head easily with one finger on the left block and one finger on the right block for example.

This leaves the long belts. Sometimes the printed tensioners are not enough. If you put the head in the corner and pluck the belts and use a guitar tuning app on your phone pitch should be around 100 to 200 Hz.

More details on why backlash causes what you see in the final photo:

https://ultimaker.com/en/community/2872-some-calibration-photographs#reply-15474

[gr5 2,230]

The middle two photographs show horizontal layer lines. Random layers that are over extruded (stick out) or underextruded (stick in or even have holes).

This could be caused by varying width filament (extremely unlikely) oscillating temperature (slow oscillation - over one minute oscillation) also not particularly likely, or Z issues (most likely).

Try cleaning the top of your Z screw (the part used for the first 3cm of printing a small part) to see if that helps - realize that it is a triple helix so only following one thread with a q-tip and you will miss the other 2. Not that a q-tip is the best tool necessarily. Your fingernail or a toothpick and some tissues are a good start.

Below is a before and after with just ONE MINUTE of cleaning:

[gr5 2,230]

If you want it really clean it's best to disassemble and remove the Z screw and clean it with WD-40 above newspaper and then dry it well and then add one drop (one pea sized drop) of grease. Best to clean the Z nut as well.

[neotko 1,417]

Most probably your bed bearings (flanged square bearings) are just bad quality . Check this post

https://ultimaker.com/en/community/11123-z-axis-layer-error?page=last

Cleaning will help for a time

Made a manual to clean the Z

https://www.youmagine.com/designs/z-screw-cleaning-manual-for-um2-umo

But most probably you just have bad quality bearings. I had to change all shafts and flanged bearings of my 3 umo+ to get good quality. I bought Misumi CF (cost effective is half of their expensive price)

[Allgeuspezl 0]

Thank you for the quick replies I'm gonna try out the methods and see if they work