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Posted · Frisky first Layers

Lately i printed a lot with PETG and havent printed with PLA in a while. for a new project i picked up a new spool of PLA. its the amazon basics brand gold colored PLA. i think it prints quite well, except for the first couple layers. they are very frisky like there is way too much filament. it looks like as soon as it prints with infill instead of solid for the bottom layers its fine. i tried changing a lot of settings. here are the settings:

Nozzle temp.: 190-215 (i tried changing it without different results)

heatbed temp.: 55-65 (same thing. i tried varying the temperature)

line width 0.3-0.5 (different line widths didnt change anything)

infill: 40%

layer height: 0.12

Flow: 100-113 (varying didnt change the results)

initial layer flow: 100-115 (same thing)

print speed: 20 mm/s

 

i am printing on a heavily modified anet a8. its got a metall frame and auto leveling sensor with bowden extruder.

if you need any other information please tell me. this bugs me and i really hope to get it solved.

 

i hope the pictures show clear what the issue is.

IMG_20200907_154125.jpg

IMG_20200907_154104.jpg

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Posted · Frisky first Layers

I don't know the answer but the first thing I thought of when you said you've been printing PETG and switching to PLA is "the teflon part".  I don't even know if you have teflon in your hot end but when you print a lot of higher temp materials and switch to PLA one often finds that the teflon part got soft and deformed and causes lots of problems (typically underextrusion but also possibly variable extrusion: stick/slip).

 

Cura sometimes prints slower on the lower layers and with less fan and the lower layers are closer to the heated bed so of course one would assume it's related to one of those 3 things.

 

Fan failure would explain everything - some fans won't spin at all until you get to 100% fan which would be a few mm up from the bottom.  So check that your fan spins even at 50% fan setting.  PETG doesn't need as much fan.

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Posted · Frisky first Layers

i dont have teflon in my hot end. so i dont think it has to do with that. 

i just started a new print and the fan is going at 50% and doesnt wait till i reach 100. so i dont think that is causing an issue either. 

i try printing with only 3 bottom layers now, so i will get to the part with the infill quicker... i will post an update as soon as i can see a result.

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Posted · Frisky first Layers

now with only 3 bottom layers the whole "friskiness" isnt showing up as high any more as it was before. that means it has to do with too much filament being there in the first couple layers with nowhere to go. but i tried printing it with 95 % flow. and it still did the frisky stuff. so what can i do to stop it from happening?

 

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Posted · Frisky first Layers

Could it simply be you have a leveling issue where the nozzle is too close to the print bed and it takes 5 layers to finally come to a steady state?

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Posted · Frisky first Layers

i am actually investigating in that direction right now. i have an auto level sensor but unfortunately i found out it is not mapping the bed correctly. in the very center of the bed it is the correct distance away but as soon as you go a bit off center it thinks it needs to go closer to the bed or further away than it actually needs to. so i am looking into that. and turned off the auto level and tried leveling it manually and that gave me mixed results but it is getting better. now i have layer delamination though. so something isnt right. i will update this post as soon as i found the solution for everything.

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Posted · Frisky first Layers

layer delamination is common - it means the hot layer you are putting down is not melting the layer below so they aren't sticking well.  This is very rare with PLA but common in higher temp materials like PETG.

 

1) Lower fan speed.  Play with your fan until it sounds like it is half as loud.  Go quieter half again.  Write down that fan % and use that in cura for PETG

2) Raise printing temp (usually this is not advised - I think most manufacturers like around 240C for PETG?  Look it up)

3) Raise air temp - if you have heated bed and if you can enclose the printer - even just the 4 sides - this will help keep the part from cooling too much.  I like 80C for heated bed temp for PETG.

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