UM2 Z-Stage movement

[Nicolinux 288]

Hi guys,

I noticed that the threaded rod wobbles noticeably when the z-stage moves. I am a bit senstive to this because of the trouble I had with the UM1 until it was fixed (http://umforum.ultimaker.com/index.php?/topic/2716-cannot-lower-bed-to-reach-endstop/).

Take a look at this short video. Is this normal?

Thanks.

 

[mnis 11]

Hello Nicolinux

So with my UM2 the threaded rod of the Z-axis wobbles not as clearly visible. That sure looks not nice, but I think that it has no influence on the positioning accuracy. I suspect the two thick linear waves are able to compensate quite sure the problem.

But for that I have entirely different concerns with my UM2. Unfortunately, nothing works right from the start.

I fight against one-sided object distortions, seemingly uneven temperature distribution on the heater bed, and collisions with pre-printed parts. But for that I'll probably have to open an extra thread.

Markus

[illuminarti 18]

I noticed yesterday that mine wobbles a little bit, but perhaps not that bad. Haven't noticed any z-related print quality effects however.

I guess the real question for you is - do you see any banding in the print?

 

[Nicolinux 288]

Sadly I do see banding :sad:

I didn't change the temperature, just switched filament:

 

[Nicolinux 288]

Forgot to mention. Print settings:

 

• layer height: 0.2
  
• shell thickness: 0.4 (single wall on purpose)
  
• bottom/top: 0.6
  
• speed: 40
  
• temperature: UM2 PLA defaults (220°)
  
• retraction: on
  

 

[oswaldo-salzano 2]

Hi Nicolinux!

Try to change layer thickness to 0.1 or less and speed to 20 and see if the banding persists.

[Nicolinux 288]

Ok this is weird. I changed the layer height to 0.1 and speed to 20 and I see no banding.

The print came out a bit harry but after a nice shave I could see the very smooth surface. Although there is another issue but I'll save that for later.

The thing is - what do I learn from this? With the Ultimaker 1 I was able to print this object smoothly at 0.2 layer height and way faster.

 

[IRobertI 520]

Could it be fluctuations in filament flow? Try printing with the same settings that produced the banding but increase the temperature. I've been printing everything on my UM2 at 235C whereas on the original I could, depending on filament, go down as low as 190C sometimes.

 

[Nicolinux 288]

Interesting theory. But this might be it. I noticed that as soon as I print at 230° or higher, the surface is mostly free from artifacts. Until now I also changed the layer height to 0.1 and thought that the thinner layers might mask the problem, but I'll try to print the same object at a higher temperature.

 

[gr5 2,172]

The UM2 prints slower than the UM1 (It can move fast but it extrudes less volume per second). So making the layers thinner or raising the temperature both can potentially help certain issues. I still don't quite understand why a little underextrusion would make this pattern though. Maybe it's something that has nothing to do with underextrusion.

 

[Nicolinux 288]

Daid responded to a question of mine where a similar patter emerged when I activated "spiralize contour". It could be a software problem (link).