Shifting, bending and stepping layers on shell model

[Teofil 0]

Hello,

For the past weeks I started to have an interesting problem printing a shell model with Ultimaker S5. 

The model itself is a airplane fairing modeled in rhino (here is just a part) - the surfaces are smooth, no bends 

So, first I test printed it in PLA with PVA support - the result was ok-ish with some hard to see bends - however, it didn't matter since it was just a test to see if it fits properly on the plane.

The next step was to print it in PETG (Polymaker Tough PETG white) since it will be outside and exposed to the elements. After a first few failed prints with common problems for this material (oozing, stringing), and some weak layer adhesion, I played with the settings and got to a sweet spot. I ditched support entirely since it would get between PETG layers and add to the weak layer adhesion (also, the model prints just fine without one).

However, since then, I haven't been able to print the piece completely. From a certain point on, I either get layer shifting, bending, stepping, or, like in the latest print, all three of them. It's important to note that it doesn't happen in the same spot - it is random.

At first I suspected somebody in my office may have *nudged* the printer - however, these errors also appeared when nobody was around. So next I checked the belts, pulleys and axis - these too seemed fine (didn't move, I couldn't tighten the pulleys anymore). Next, I suspected that the temp was too high inside the print box and some kind of warping was occurring, so I lowered the hotbet temp. This too, didn't help. Next, I checked if the walls somehow moved on the bed. Checked, no movement - and now I am out of ideas. Here are my settings for the last print where I have all three problems

 

 

For comparison, PLA (black) vs PETG (white) see pictures below. For PLA no layer shifting, just some deformation, for PETG we have both + stepping layers (incline)

I read this post and wondered if there could be an electronics problem also - if so, how could I check? Should I send it to the reseller? 

 

If someone in the community has encountered a similar problem, any help would be much appreciated!

Thank you and have a nice day!

 

[geert_2 558]

If random, it looks like a mechanical thing, or unstable electronics.

 

With power off, check if the head moves smoothly and easily, without hard points? Too much friction could also be a cause.

 

For the belts and pulleys: with a marker pen, write a line from pulley to rod. So you can see if they move.

 

On an UM2 with SD-card, I would say: check the card and slot for dirt. But I guess the S5 has an USB-slot, that shouldn't cause issues. If via network, maybe unstable connections and data loss? In the old days, when a driver overheated, it could for a moment switch off and cool down. But I haven't heard about that in the last years. If there are cooling fans for the electronics, check if they are working fine? No smell of hot electronics?