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Wavy/irregular lines
#1
I've been seeing this issue for a while now where some layers of filament are not straight but wavy, irregular, messy, like in the picture below. This is mostly seen while printing the brim, but also sometimes it continues over the first few layers of the printed object, then it all goes back to normal. However it typically happens only on some of the sides of the object, not on all of them.

Here is a picture of a brim exhibiting this issue. Note how the first (outermost) lines are perfectly straight, but as it moves inwards some of the sides begin to get messy.

[Image: IMG_0006.JPG]

My main suspect is bed leveling issues, i.e. the nozzle is too close to the bed and the extruded filaments keeps getting blobs of plastic, and these imperfections keep adding up and affecting the neighbor lines. However this does not really explain why the issue occurs only on some parts of the brim and not in the others (and in this pic it's a fairly small rectangle).

Here is another pic of the (I think) same issue manifesting over more than just the first layer. In this cube, the side shown is the worst one, but of the other 3 sides, one exhibits just a bit of the issue, and the other 2 are perfectly fine.

[Image: IMG_0007.JPG]

Any ideas of what could be causing this?

PS: in case you are wondering, the black surface over which I print is a sheet of BuildTak, a product that works pretty well for improved adhesion. However it does degrade significantly over time, and this one I'm using now has seen a lot of use and abuse, so it's about time to install a new sheet. Will see if that fixes it, but I kinda doubt it.
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#2
This is an area where I am still definitely learning and dont claim to know the answer to this one. From my testing, I tend to get this when Im trying to crank up the heat and mess with extruder offsets to get the print to stick. I typically change one thing at a time so I gain some working knowledge on how to overcome issues or stop potential problems before I start printing. If this was me, especially if the wavy layers are curling upwards a bit, Id drop extruder temp 2 degrees at a time to see if Im going in the right direction. If that didnt change anything I would try to speed up the first layer a little so the extruder spends a little less time touching the layer. If no success there, I start messing with zoffsets and start playing the stick/no stick game until I find a happy medium. It is a little concerning that you are seeing this on what looks like the first 5-6 layers. Was your bed really hot for the cube run?

I agree with you in that z offset is a prime suspect. Wavy lines on first layer and the elephant foot at the bottom of your cube shows this. If thats the height you need in order for prints to stick, play with temps.
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#3
I run the bed at 110ºC with ABS, and rarely have adhesion issues. It might be a tad too hot though, but if that were the cause then all sides of the cube would exhibit the same issue, I think. It's very odd... I'll keep playing with the leveling and temps anyway. Didn't think about the first layer speed, but will try that one too.
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#4
So, I had this issue with the starter filament and then switched to a new spool and the issue wasn't there. Are you seeing it with all of your filaments?

Jess (PS I'm still n00b!)
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#5
the other suggestions provided are great starts. You might also make sure the glass need is not shifting, check z wobble, and make sure no bearing mounts are cracked. The reason i am suggesting this is because side shift appears to be more likely in early layers, and a cracked bearing mount might cause shift in one direction but not another. This doesn't explain the one sided effect, but maybe a could of these like bearing mount and temperatures are combining to create the effect. Hmm, also don't rule out a hot spot in the bed - try shifting the prints position and see if the problem moves.

Kieth
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#6
oscahie, did you get this one resolved? If so, mind sharing the combo that resolved it? I see this all the time on the first layer but have never seen it on subsequent layers unless my hotend is way too hot for the filament, which would render your entire cube looking like layers 1-5 or so. Is this AFTER you replaced the extruder heater? Wink
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#7
Not yet, I haven't had time to do more testing as I'm working on installing the E3D Smile If the issue persists with the new extruder then I'll see how can it be fixed. I think that the issue was already happening before with the stock cartridge heater but I can't remember for sure.
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