Underextrusion after seam?

[Theo123 0]

Hello!

I am having an issue with what settings I need to change in order to fix this.

 

The print is having issues just at the beginning of a layer change right after the seam. You can se on the first image that just right of the seam (drawn in red) the filament is looking a bit wierd, like slightly underextruded or just off in temperature? Im not sure what is is.

You can see the same issue in the second image. Just to the left of the seam (the extruder goes counter clockwise for the inner wall).

You can also see an issue with the seam of the inner wall. It is a slight gap in the seam.

 

My thought is that I probarbly need to change the retraction setting somehow. Maybe there is not enough pressure/heat in the extruder after the z-hop?

I use the following settings in Cura:

 

Edited April 3 by Theo123

[Slashee_the_Cow 493]

It's hard to see in the photos (which probably means it's the sort of thing you're going to notice because you know it's there but other people won't).

 

If you want to increase the pressure after a retraction, increase Travel > Retraction Extra Prime Amount. Probably doesn't need to be too high, but I've never tried it so I can't offer specific advice on numbers. That makes it push a bit more filament into the nozzle than it retracted to make sure the pressure is high enough when you resume printing. Remember though, small scale testing is your friend: if this is something which is apparent even in the first few layers, then when you test after changing things only print the first few layers, not the whole thing.

 

Printing with a 1mm nozzle is always a bit hard but it's good to see you've (probably, I don't know your normal settings) accounted for that by lowering the speed and increasing the temperature.

 

I would recommend turning down the acceleration quite a bit (down to maybe 200mm/s²) and turning on Speed > Enable Jerk Control and lowering it to 4mm/s². Since you're printing at such a low speed this will help make the speed consistent because it's not turning a corner and zooming off as fast as it can before it has to slow down for the next corner (admittedly not too far in this case, but still).

 

You may want to try enabling Walls > Outer Wall Wipe Distance with a setting of about 0.4mm. This makes it so that when it finishes a wall it keeps moving the nozzle a little past the seam without extruding, the idea is if there's anything left in the nozzle it uses that to fill a gap in the Z seam if there is one.

[Theo123 0]

Hi, 

 

Thank you for the response. I´ve tried changing the settings as you suggested and I still get this issue in the beginning of every layer. I'll post another picture that might make it easier to see the issue. Can you help me? @Slashee_the_Cow

[Slashee_the_Cow 493]

If you could provide the Cura project file (.3mf, in Cura get it ready to print then go to File > Save Project) that might help, since I can look at the settings and where the Z seams are and such to see if anything strikes me as odd.

 

Although looking at your pictures, it seems like your project has a cross section something like this?

\_| |_/

You could always cheat. Since it seems to be the inner section giving you problems just do it separately in spiralize mode (no Z seams at all!) and glue it to the other piece 😉 

[Theo123 0]

FSR_2024-03-27 .3mfHere is the file. 

 

 

[Slashee_the_Cow 493]

Also I just remembered that @jaysenodell (I'm pretty sure, anyway) has been working with bigger nozzles lately (even if not quite that big) and notice that mention and possibly have advice.

[jaysenodell 18]

Yep.. that was me. 1.0mm noz for big tubes that eat entire 1kg spools at a go. I'm dumb. 

 

I found the problems to be

• Retraction extra prime amount - 1.5mm3
• SLOOOOOOOOOOWWWWW DOOOOOOOOOOOWN ... this is for PLA
  • Print speed - 50mm/s (my normal is 80mm/s which will make slashee call me names)
• ZSeam aligment - Random
• Outer wall wipe distance = 0
• Layer height - 0.6mm

I get a textured surface (ridged) but no holes in the layers.

 

If you see underextrusion middle of a layer you may need to increase noz temp to help the booger string flow. I wound up at 200.

 

The two biggest factors were print speed (slower is better) and the prime amounts (there is more than retraction prime, that's the only one I needed to change). 

 

Let me know if I can be of any help. 

[Slashee_the_Cow 493]

Well it's definitely prettier than a lot of models I've tried to troubleshoot 🙂. Some observations:

• You put in a ChangeAtZ post-processor to speed up the top four layers? I can't think of any good reason to do that (but feel free to explain your reason, maybe it's just good and I couldn't think of it)
• I hope this thing doesn't collapse under its own weight at the top because there's no infill. But given how much filament infill would add, I can see why you'd want to avoid it.
• This thing is going to be weak. The kind of "pick it up from the bottom and cradle it when you move it" weak.

Okay, done with the observations. Now the suggestions (and I might be using some of the more advanced settings here so if you can't see them, just search for them):

• Turn off Travel > Retract at Layer Change: At the extrusion distance and speed you're using, it's not going to be doing the retraction in then back out fast enough. Do this one. I mean it. Any stringing is going to be on the inside of the print, hidden, anyway.
• Turn off Experimental > Use Adaptive Layers. We want to get a consistent flow rate and adaptive makes it different for different layers.
• Seriously consider using two 0.6mm walls instead of a single 1.2mm wall:
  • As well as Quality > Line Width, you're going to need to change Walls > Minimum Wall Line Width to 0.6mm and turn off Walls > Print Thin Walls
  • It reduces the flow rate - that makes it easier for the printer to control the flow
  • Retractions will be more effective since it only has to retract half as much filament (by volume)
  • We can put the starting Z seams on the inside wall so if the problem is when it starts a line it'll be hidden. For that you'd need the following settings:
    • Walls > Optimize Wall Printing Order turned on
    • Walls > Wall Ordering set to Inside To Outside
    • Experimental > Group Outer Walls turned off
  • If the problem is when it ends a line, just use the the settings above but with Wall Ordering set to Outside To Inside
    • If it has problems at both starts and ends, then obviously another fix needs to be found
  • Yes, it'll take nearly twice as long to print. Slow print > bad print
  • It'll make it marginally stronger. Like, just so little it's barely worth mentioning. But it's science! The thinner something is, the more likely it is to bend instead of break. PLA is pretty brittle so tends to default to "break"  and this probably won't change that, but I'm weird in that I subscribe to the "in theory, it'll help" way of thinking, not caring about the "in practice, it won't make a difference" part
• Turn down Speed > Travel Speed to 50mm/s. Filament can be a bit clingy, especially when you're extruding a lot more than someone on a 0.4mm nozzle would be, and I've seen travel speeds so high they've literally pulled parts of the model with them, making them warp
  • I'll admit, this will likely make no difference. But your print has so few travels it barely adds anything to the print time so it can't hurt
• As @jaysenodell mentioned, you could set Walls > Z Seam Alignment to Random but that is sort of a cop out in that you might still have the problems, they just won't be nearly as noticeable because they're not all in one line. It will introduce a lot more travels but if there's any stringing, thanks to combing, Cura makes them all go around the hole in the middle, so they still won't be visible from the outside

 

55 minutes ago, jaysenodell said:

Print speed - 50mm/s (my normal is 80mm/s which will make slashee call me names)

%!&*ing hoons in their Commodores doing 80 in a 60 zone. Where's a cop when you need one?