Random banding issue. Layers don't line up perfectly.

[pjfossee]

image.jpgimage.jpgimage.jpgimage.jpgimage.jpgHi. I was wondering what causes the layers not to line up in the pictures. I thought it was z banding but my layers not lining up is random. Also, the layers that don't line up seem a bit underextruded on all sides of the 20mm calibration cube eliminating a loose x or y axis both of which i have tightened multiple times. Also, in the one picture it looks like my bottom layer was extruded inconsistently, which I thought might be connected. I initially thought underextrusion was the problem and while extruding more does help minimize the banding (see right block in pic of two black blocks), it creates overextrusion issues in other places. It seems that a high temp also helps the problem. But the temp was 235 Celsius which seems a bit high for black PLA. Any ideas what might cause this random banding? Thanks

[3dex ltd]

Is there some play in your nozzle? This could happen if the nozzle could move about a little bit. Make sure everything is rock solid.

[pjfossee]

I just tightened all the axes. Probably a little to much. There was a fair amount of resistance to movement. Anyways, it helped a little bit, but the issue is definitely still there. I'll post pictures when the next print is done.

[pjfossee]

dstar.jpgdstar1.jpgdstar2.jpgdstar3.jpgHere are a few pics of my new print. Looks a bit under extruded on the sides but maybe over extruded on the top. Or maybe that's just because of the slicer. I guess this thread has just turned into a critique my print thread. I notice that the filament occasionally makes a faint crackly sound when being retracted. My retraction is at 3mm. Also, I printed at 100% flow and my e-steps are calibrated so my extruder is pushing the right amount of filament through (I measured). I am trying 110% flow just to see what happens. I appreciate any advice. Thanks. Here's some print info:
Print speed: 30mm/s
Nozzle Temp: 230 Celsius (high temp explained in first post)
Bed Temp: 60 Celsius
Filament: MakerFarm Black PLA
Layer height: 0.1mm (0.3 mm first layer)

[LambdaFF]

Hi,
I think that the way you approach this is not systematic enough.

If the e-steps are calibrated OK, don't play with it, you'll just mess the situation for the filled layers (and notably the first ones). Unless of course your filament is not perfectly 1,75mm.
By the way, why do you print a very thick 1st layer ? Are we talking raft here or real first layer ? If the esteps are not set properly, you will overflow your layer and that will mess the following ones. Same if the Z-offset is not set properly.

The temp is way too high for PLA. This seems suspicious in itself.

Try printing slower and see if that brings you to a cleaner print for at least a temporary solution.
Is the movement smooth on all axis ?
Have you lubricated the rods ?
Is your extruder knobbeed bolt / gear / whatever clean ?
Do you have a cooling fan on the print while printing PLA ? That ALWAYS helps.

[curious aardvark]

yeah 210 and a cooling fan.

That doesn't look like 0.1 to me either :-)

try 0.2 - 0.1 might just be too little plastic coming out.

[pjfossee]

Thanks for all the reply guys. I'd been going at it systematically for two weeks but ran out of ideas to be honest. Temp and flow rate seemed to help but I think they just masked the real issue. I will go back to the settings suggested above and let you guys know how it goes. Maybe from there you can give me a suggestion as to what to fix. I will recalibrate e-steps and check my z-offset again too.

[pjfossee]

Oh and my first layer was thick because cura said it provided better bed adherence and I just went with the default. Should I match it to the rest of the layers? I'll do that for my baseline test. Thankss.

[pjfossee]

image.jpgimage.jpgimage.jpgimage.jpgimage.jpgHere's a print I did going back to my basic settings.

Print temp - 210 Celsius
bed temp - 70 celsius
print speed - 30mm/s
layer height - 0.2mm
initial layer height - 0.2mm
retraction - 4mm
retraction speed - 30mm/s
infill - 15%
shell width - 0.8mm (0.4mm nozzle)
flow - 100%
makerfarm black PLA
cooling fan enabled on full speed
e-step calibration was good
bed leveling was good
z offset was good

honeslty im just glad I can print objects this cool. But I would like to improve it. Two thoughts I had were that maybe my Hobbed bolt isn't tightened right causing inconsistent extrusion or maybe my PLA has absorbed water because it's hydroscopic. I know I can put the PLA in an oven to dry it out but I don't know how tight my honbed bolt should be. Could someone let me know? And other ideas. Thanks! I really appreciate it.

[moyesusa]

I run PLA with about the exact same settings except for retraction speeds.

I'm using 1mm retraction and 20mm/s for the speed. YMMV

-moyes