Help me identify this problem... :) UM2

[moonyos 0]

I've been printing a series of benchys and I keep getting this strange artifact and some shallow holes on the surface of the print.The holes have been happening on both sides of the benchy and around the same area. I thought it was under extrusion so I upped the temperature for the white bench you can see it was over-extruded on the same spots as the other benchys. I'm also seeing diagonal lines only on the little cabin. All the prints have these exact lines and i'm unsure if either its normal or if its a loose belt or something. I'm running a UM2 with the olsson block upgrade and a .4mm nozzle size. Please see the images below, what would you say is causing this...any possible solutions?? Thank you!!

 

 

 

 

[gr5 2,172]

Those diagonal stripes we call "zebra stripes".  Google about it in this forum e.g. "site:ultimaker.com zebra".  There's a nice video that explains what causes zebra stripes and a nice way to fix it posted by I think "triangle labs".

 

I sell a kit that takes care of this.  Or you can get it on aliexpress:

https://thegr5store.com/store/index.php/tl-smoother-removes-zebra-stripes.html

 

The other issue I'm not so sure about.  Hopefully someone else has an idea.

 

[moonyos 0]

Thanks for the response! I checked out the link but the installation instructions link leads to a dead end webpage. I'm going to look into this upgrade.
    I also included more pictures below with the same hole type artifact. It can't be the nozzle since I just upgraded to the olsson block. This material is colorfabb xt printed at 245 degrees with a speed of 50mm (outside walls as per Cura 25mm). The white benchy above is the normal colorfabb PLA printed at 220 degrees (all the others are colorfabb xt). You can see that the white benchy over extruded on those same exact spots as the other benchy's where instead holes were created. I'm just not sure if this is a temp issue, start and stop point issue, or like a jerk acceleration type issue. Maybe all! lol. If you see the guys pant vs his cape...there is a notable difference in smoothness. Thanks for all the help!!!

 

[gr5 2,172]

How thick is your "skin"?  Your walls?  Is it at least 2 passes?  Are both passes the same width?  You have to look at several settings to determine this.

 

My first thought was underextrusion - but no - that's something else.

 

Make sure you have 2 passes on your wall (e.g. with .4mm line width you want 0.8 wall (or 1.2mm)  - if you make the wall 0.7 then it will probably to a .4 pass and a .3 pass).  Best to make the line width agree with wall width.

 

[geert_2 557]

Just a question: could an effect as in the man's hair be created if there are too much line-segments in a too short distance? So the printer has to slow down? For example 100 little segments of 0.01mm, instead of 1 segment of 1mm? I vaguely remember reading a post where too much STL-triangles in a model created a similar problem?

 

The indentations in the white boat rather look like a start-stop effect to me, after the nozzle arrives from somewhere else? Maybe you can see in the slicer if they mark the start of a new layer?

 

Also, I noticed that blobs in PET are quite common: this material is rather thick and rubbery, and it tends to accumulate on the nozzle. Then after some time this goo sags and gets deposited on the print, usually as a light-brown blob. But that gives thick outwards blobs, not indentations. So this might be a cause of some fo the blobs in the man's weapon shield, but not of the indentations.

 

Maybe you could cut the model into little pieces, and only print those where the effects are worst? And then keep watching if and when it happens? So you don't waste too much time and material? Sagging blobs of goo, and layer start/stop effects schould be clearly visible.

 

[moonyos 0]

Thank you for the responses! I've posted my cura settings below for this print. I think maybe i've set the skin top/surface layers too low? I see what you mean regarding the XT material. It does get gooey but I tested the temperature settings for this filament in 5 degree increments starting at 230 degrees. I rested on 245 which should be ok for this material since the recommended settings are 240-250. I included more of the benchy pictures. There are two pictures for the orange benchy on each side where you can see that artifact happening again looking like a hole. On the white benchy it looks like over extrusion especially the circled picture. The hull of the white benchy's artifacts have a uniform slanted scar going up the side. Still pretty stumped lol!

 

 

[phantom 17]

Did you ever find out what the problem is?