Partial Answer Why does my ditto have stretch marks?

I'm getting this mark on every ditto I print regardless of print quality setting. I'm not sure why. the mark is more intense when printing at High quality than normal and it's always in the same spot. I have also seen this on other prints that have a curved surface.

Printer: C2
Filament: Pink PLA
Bed Temp: NA
Bed makeup: C2 replacement sheets
Slicer: Cura for Robo

Ditto specific settings:
Qualities tried: Normal and High
Other configurations tried: No infill with doubled thickness. Solid infill after using Meshmixer to create a shell.

Other print settings:
Normal Quality PLA Low Infil.

Ditto:

Other:


Edit: I used to have this in the R1 forum but was moved to the C2 forum

 

Thanks

 

How do I find that in Cura for Robo? Sorry, forgot to add that in the post but have it there now.

 

Just found it under Preferences > Configure Cura... > Settings > then check "Z Seam Alignment" to have it show up in custom settings.

Will try this tonight and mark as resolved if it works

 

If it were me, in my slicer, I'd rotate the model 180 degrees at the base and see if the stretch marks move to his back.

 

In the Air Force, I went away to a course called "black box troubleshooting" and one of the troubleshooting techniques was called "divide and conquer", basically applying a binary search approach to what could be causing the problem. Find a litmus test to divide the problem by half then chase the remaining half with recursion.

Is it the slicer or printer? (try to find some test/activity which allows you to know definitively that it's not the printer causing this)
Okay, we now know that it's the slicer doing this.
Is it the layer start pattern or the retraction event that's related to the move at the end of the last layer? (try to find some test/activity...)
etc

 

I printed the ditto with the random z seam alignment. The really noticeable seam is now gone but there are now smaller notches all over the print. I don't remember having these before. How would I clean them up?

 

I have not done this nor do I know how to.

 

I followed the instructions in the video and found my printer was only extruding 95mm when I asked it to extrude 100mm. I adjusted it to 105.26% flow but am seeing almost the same issue. I printed on NQ with random seam locations just like the last one. I am trying again with nearest seam location to see if the seam is as intense.

 

This is going to sound like it's not related, but it is...

I lived near a guy who's old enough to have been in ballistics in the Army back in the Korean war era or something like that. He said they'd sight in a remote target and then send a tracer over and watch where it lands. The next shell is then overshot and they watch where that one lands. And then the third shell was always on target because they interpolated between the first two attempts.

Now as it applies: If you thought that you hadn't yet ruled out extrusion rate, then try for 110% extrusion and hope for some globs/strings (perhaps) on the surface instead of what you're seeing now. It might be possible to measure the indentation maximum from before, the glob-height from the over-extrusion attempt and then interpolate. What if 108% is the magic number? Until you've actually overshot, then how would you know?

 

I tried doing it at 110% but it looks exactly the same as this ~105% and 100% one. This makes me think the printer is completely ignoring the flow change. I'll try changing it in the settings on the printer to see what happens.