Surface artifacts when formation of object changes (Layer inconsistency) When my Ender 3 prints a top or bottom layer, it leaves a line on the layer. 





Slicer Cura
Linear Advance: 0.57
Retraction: 3&nbsp;mm @ 35&nbsp;mm/s
Max Speed: 100&nbsp;mm/s
Ironing enabled
Minimum wall flow: 20&nbsp;%
Temperatures: 205&nbsp;&deg;C hotend and 65&nbsp;&deg;C bed


My belts are tight enough as I push them they spring back up. I bought a support block for my Z lead screw to help with z banding (I also removed it to see if it will fix the issue but it didn't). I tried 50&nbsp;mm/s, No Infill, swapped out to brand new 0.6&nbsp;mm nozzle (the picture has 0.4&nbsp;mm), Minimum wall-flow to 0&nbsp;% but no improvement. It has to lead me to think its a mechanical issue but I am not sure where to start.
I have found the issue. My extruder gear was deformed after 4 months of continuous use which made the extruder have a difficult time when a rapid change in extrusion happened. I swapped it out to a new stainless steel one and it has been working well so far.
EDIT:
These inconsistencies are mainly caused by the pressure in the nozzle not changing fast enough. So to solve this you should look at the extruder setup as that is where the pressure is being controlled. Get any gunk out of there and make sure the path is clear and make sure nothing is grinding and you have a good grip on the filament.
To reduce the change in pressure you should play with printing speed, hotend temperature, linear advance if applicable and you may tune extruder jerk and acceleration although not necessary.