@chanders Hmmmm... Makes me want to check whether I could fit the lower half of a soda can into my printer...

Got it. I recently moved the printer to a new place - from one flat and level surface to another - and I didn't bother to re-level it. That came to bite me now - one of the corners (the front right) was considerably lower than the other ones, introducing a twist into the entire frame that was really hard to spot. Re-leveled the feet, now everything is back to normal (pun intended).

@SIam said in first layer extrusion (?) issues:

@vwegert Have you tried to clean your print bed ? For me, it looks like that you have some fat or oil on the bed

I usually clean the print bed once every 5 prints or so. I just cleaned and de-greased it again, with very little effect.

Slowly making progress... First I removed/reduced some extrusion multipliers and perimeter/infill overlaps - that did help to reduce the issue a bit, but not remove it entirely. Same with increasing the first layer height. At this point, the central "ridge" that started right at the beginning was gone, but the "sand dunes" across the length of the piece with the weird extrusion patterns underneath (image number 4 above) were even more pronounced.

Temporarily disabling the mesh calibration did NOT help. I doubt at the moment that the mesh calibration has got something to do with it.

With an initial layer height of 0.36, I've had to babystep up an additional 0.15 mm to have any noticeable effect on the "sand dunes". Only at 0.36+0.2 mm did the pattern disappear entirely, but then I ran into the problem that the perimeters and infill disconnected again.

At this point, I was wondering why the second layer always worked so much better than the first one. I still had a a speed reduction for the first layer in my profile; since I do not have any model adhesion issues I know of, I removed that and was able to get an improved, but not perfect result with "only" +0.1 mm babystepping.

At the moment I can't really see what's happening during the print - I'll have to see whether I can convince the slicer to produce the infill back to front or rotate the entire g-code somehow.

Different part, much simpler geometry. This time I remembered to take some pictures of the first layer.

In the front it looks like there's some kind of ridge forming; behind that, there are something that looks like waves... Maybe overextrusion that's being pushed around back and forth on the hot bead like kneading dough... Don't know.

The second layer is completely smooth (except where that ridge in the middle pushes through a bit). This print will take another hour - I'm curious to see how what I'm seeing on the inside translates to the outside.

To be sure, I re-ran the calibration...

Number of points: 137
Probing radius: 130 mm
Probe area: 530.9 cm²
Maximum deviations: -0.170 / 0.101 mm
Mean error: -0.040 mm
RMS error: 0.052 mm

@Veti said in first layer extrusion (?) issues:

it looks like you have a very slight ripple.

That might be the case (though I can't detect any noticeable backlash) - however, I don't quite understand how that might change the extrusion results essentially doing straight lines right next to each others.

Number of points: 137
Probing radius: 130 mm
Probe area: 530.9 cm²
Maximum deviations: -0.156 / 0.067 mm
Mean error: -0.059 mm
RMS error: 0.041 mm

I'm running into some interesting effects on my first layers. My printer is a Delta with an original Bondtech extruder and smart effector with a genuine E3D V6 hotend and a 0.4 mm nozzle, with about 60 cm of Capricorn bowden tubing. Duet 2 Wifi, RRF 3.2, with mesh compensation. I'm using Prusa Slicer 2.3.0+, obviously with a custom profile. I'm really unsure what I'm looking at and where to start tweaking.

First of all - the layer height. I've set the initial layer height to 0.3 mm, but measuring the skirt with a micrometer, I get a thickness of about 0.19 mm (20 samples, ranging between 0.11 and 0.26). I have double-checked the g-code and confirmed the first layer height:

;LAYER_CHANGE
;Z:0.3
;HEIGHT:0.3
G1 Z0.300 F7800.000

Is it normal that the first layer is way lower than set in the slicer, even with G32 run immediately before the print with both the bed and the build plate heated up?

But on to the extrusion issues. Here are some images:

1 - Ignore the diagonal "line" going radially out from the large hole, that's apparently from a travel move above the first layer. The defects to the right of the number are very noticeable, I'd estimate up to 0.1 mm deep. Meanwhile, the (unlit) top right corner has a perfectly closed surface, no gaps at all.

2 - These ridges are very deep again, almost like the ones before.
3 - I can not see anything in the sliced model that would account for these broken lines.

4 - These ripples would look cool on an art project, but what's causing these? There should not be anything other than a smooth closed surface.

5 - Different part of the same print job. Again - nearly perfect surface where I've placed the number 5, broken / stepped surface ridges to the left of it.

6, 7 - more examples of the quality changing drastically almost from one line to the next.

I don't have a clear idea what might be the cause of these issues - has anyone seen something like this before?

Got it. I recently moved the printer to a new place - from one flat and level surface to another - and I didn't bother to re-level it. That came to bite me now - one of the corners (the front right) was considerably lower than the other ones, introducing a twist into the entire frame that was really hard to spot. Re-leveled the feet, now everything is back to normal (pun intended).

@Phaedrux said in Delta X/Y - um - "undulations"?:

Loose grub screw on a motor shaft?
Cracked piece somewhere?
Stiction somewhere?

None of these, I'm afraid. cleaned and re-lubricated all of the arm joints, readjusted the trigger heights of the end stops, went through the entire delta calibration routine again, and repeated the mesh bed calibration. That got me a much more flat height map, which is good - but it didn't really do much to the original problem.

The righmost part is printed after re-calibrating the printer, and it still almost matches the previous parts in its distortions.

Looks like I managed to bend the frame of my printer
The printed corner brackets apparently start to develop some slack.
I'm no longer sure about that - or rather whether that's the real issue. I've tried to adjust for that, made another print and the two pieces fit together perfectly as if nothing had changed. Back to square one...