I've have observed that when the printer is finishing a layer, the flow of plastic through the nozzle starts fading out as it comes closer to the point of layer change.
As an example, let's say that I'm printing the first layer of a cube. The nozzle first prints the perimeters ok. Then it begins to print the inner part, beginning from one corner and finishing on the opposite one. As the nozzle comes closer to the finishing corner, the flow of plastic diminishes, resulting in the lines of the filament to touching each other.
Maybe it's not a big deal, but it's annoying because it's stopping the part of having a very nice first layer and finish.
My setup is:
- Anet A6 running Marlin 1.1.8
- Bed auto leveling before each print
- Slic3r Prusa Edition, latest release (as of 20 January 2018)
- PETG from Das Filament
I tried disabling all "retract" settings but the issue persists.
I'm beginning to think that this could be a software bug (Slic3r), but before I submit it to GitHub, I'd like to be sure.
Any opinion is welcome!
If you think it is a slicing problem, look at the G-code. You might want to arrange for the infill to be orthogonal to the axes, but it ought to be easy enough to calculate the ratio between printhead motion and the extruder. G-code is just text, and fairly easy to make sense of. The RepRap wiki has a good reference to the commands, and all you care about are X-Y movement, and E movement.
An alternative explanation might be that your extruder is struggling with the extrusion rate, and after continuous extrusion is failing to heat the filament fast enough to melt. The layer change could be providing a sufficient respite that walls start off OK on the next layer. Also check (in the G-code) that the speed of walls and infill is the same.