Surface Quality Downward Spiral. 6 months and still cant figure out.

[eyefromthesky 0]

Dear Community.

3D printing seemed pretty straight forward to me until I hit this never ending downward spiral.

I have been printing super-quality objects at 0.6mm nozzle with a 0.4 mm tall layer.

Until I started obtaining this:

Cooling problems? Seems not, as I have refurbished the cooling system and obtained same results.

Under extrusion? Changed EVERYTHING, from tubes to nozzles to hot ends to stepper motors. First print (if lucky) turns out messy yet not devastating..

Bad speed/heat combination? Don't think so, as printing in PLA I range from 220 C for 30.35mm/s to 215 for 25mm/s.

Maintainance? I regularly oil all axis.

So I changed nozzle size to 0.5mm and layer height to 0.35mm.

This is what I'm getting:

The surface seems trembling, as if the structure weren't rigid enough.

Its been 6 months of testings and now I'm at a dead end.

Cannot find any more specific threads that could solve my issue, as now it seems extremely peculiar to me.

Looking for suggestions on how to move on this case.

THANK YOU

Some INFO:

PLA

UM2

30mm/s print speed

2mm retraction

2 outlines (shell)

100%-120% extrusion width

100% flow

50C bed

215-220C nozzle

Any more info please ask

[gr5 2,070]

I'm not sure which issue you care about. I'm not sure what you are talking about. But I see 3 unrelated things:

1) poor quality on some overhangs - severe overhangs particularly bad but even 45 degree overhangs like blue model upper lip should be better. This is usually fixed for me by printing slower - I'd dial it down from 30mm/sec to 20mm/sec just in this area to see what happens.

2) very fine stringy hairs (these are very easy to remove and I've heard several theories of what cause this whipsy things but I'm not sure)

3) Some vibrating patterns in green image (this is made better by printing cooler usually)

#1 seems like the worst problem. Could it be that your models have many more triangles/faces than your older models? Cura can only plan 16 line segments at a time so when you have 16 line segments fitting into 2mm of travel it mess things up and you get weird shaky movements.

Also it seems you are changing filaments. A lot of the newer "pla" formulations do better at cooler temperatures.