What's causing this print defect?

[Paul4x4]

My FF Creator pro usually prints perfect, but it has now developed this weird problem, and this particular part I'm trying to print doesn't seem to come out well, no matter what I do...

I've been trying to print this PLA part along the x and y axis, 20% infill + 2 perimeters, 100% infill + 1 perimeter, with and without cooling, and seems like it's only starting to go worse. It's weird that most of one layer might print perfectly, but then there's one or few spots where the layers doesn't seem to fuse together at all, and it repeats it roughly at the same spot over many layers.


The problem seems to occur mainly when I'm printing parts with elongated shape, and now this particular part seems to be impossible to print, and I have no idea what's going on.

[Stigern]

I have also had these issues, so I'm curious to see what could be the problem.

[Dargonfly]

That looks weird...

What programs do you use for printing?
At what temp are you printing?
At what speeds are you printing?
Are you using any retraction or flow scaling?

[curious aardvark]

could be fluctuating diameter of filament. Looks like it's not extruding evenly.

have you tried the same part and settings with different filament ?

[Paul4x4]

could be fluctuating diameter of filament. Looks like it's not extruding evenly.

have you tried the same part and settings with different filament ?

I was thinking about that too, but that wouldn't explain why there's that repetitive defect at the same area in multiple layers...

I have printed other parts with the same settings and different filaments, with similar results, and the same settings have also yielded perfect parts. I printed one other elongated part with silver and transparent red PLA, and those had almost identical defects at the same spots, but nothing severe like with that black part. Also some small cylindrical parts I printed today four at a time, resulted with one good part, and three little bit messed up parts. This is so weird...

I'm using Simplify3D, but I think I might give it a shot and try makerware or something to print some problematic piece, to see if it's hardware or software which is acting up...

[Geoff]

I was thinking about that too, but that wouldn't explain why there's that repetitive defect at the same area in multiple layers...

I have printed other parts with the same settings and different filaments, with similar results, and the same settings have also yielded perfect parts. I printed one other elongated part with silver and transparent red PLA, and those had almost identical defects at the same spots, but nothing severe like with that black part. Also some small cylindrical parts I printed today four at a time, resulted with one good part, and three little bit messed up parts. This is so weird...

I'm using Simplify3D, but I think I might give it a shot and try makerware or something to print some problematic piece, to see if it's hardware or software which is acting up...

I know it's a silly question, but this particular piece has been netfabbed yeah? if your STL has a hole, it will present that also if the slicing program fails to register it.

[Paul4x4]

I know it's a silly question, but this particular piece has been netfabbed yeah? if your STL has a hole, it will present that also if the slicing program fails to register it.

Yeah, it's been netfabbed, so no holes.

I have a new theory of what's going on. Occasionally when I'm changing filaments, and I load the new one in, it starts extruding in very curly manner, and after I heat the extruder a little bit more, it comes out good and straight again. So could it be that I have a partially clogged extruder, and while it's printing and doing retraction moves, it starts doing that curly extrusion thing after some longer retractions, and it takes a little while before the extrusion evens out again?

[curious aardvark]

probably not they all come out curly at low temps.

What speed are you printing at ?
And have you tried printing much slower ?

Also can you attach the .stl file and I'll have a go at printing it.
At least that way we can rule in or out whether it's the file.

[Geoff]

Yeah, it's been netfabbed, so no holes.

I have a new theory of what's going on. Occasionally when I'm changing filaments, and I load the new one in, it starts extruding in very curly manner, and after I heat the extruder a little bit more, it comes out good and straight again. So could it be that I have a partially clogged extruder, and while it's printing and doing retraction moves, it starts doing that curly extrusion thing after some longer retractions, and it takes a little while before the extrusion evens out again?

Yeah you're on the money. All plastics have a slightly different melting point and you will get some curly bits coming out on a change sometimes that's pretty normal, but as you have seen they clear themselves out after extruding a bit.

I change filament nearly after every print, and often need to just jab a small piece of wire up the nozzle to clean out the gunk. PLA for me is probably the worst offender at presenting this issue, since some are 180c, 190c... 210c... ABS doesn't generally do it to me because they all are printed fairly hot.

The best advice I can give you is when you change the filament, do it slightly hotter than you did last time you changed, or just increase the pre-heat a little, just a few degrees is enough to flush most residual plastic out.


As curios said, if you want to attach it or PM it to me privately I can slice it in a few diff programs and test in on a few printers and see what the outputs like