I get some of exactly what you are describing with Slic3r as well. I don’t think it’s a software issue, and I don’t think it is a motion segment issue. I think it has to do with the extruder itself actually, and maybe the controller. On a straight run any pressure variances tend to not show up because outflow is constant. As soon as it hits a curve and that direction change though, it seems like any excess pressure from that layer, especially on a really well dialed in machine that shows no other blemishes, is going to come out at that location. Possibly a pressure wave, possibly a belt handoff issue, maybe a nozzle wobble, but that shouldn’t be an issue on my machine at all at this point. I’m not really sure yet. Slowing the speed does seem to diminish the effect. I’m not convinced it isn’t some sort of minor overextrusion. I really need to get a high speed camera now to figure out exactly what is going on there for sure though. It doesn’t seem to be taz specific either. You can see similar artifacts on really well dialed in ultimaker and mendelmax prints in similar locations. It definitly varies with layer height as well. It’s every other layer, or every two layers or so, but intermittantly too, which would make me think it’s extrusion related.
My next testing phases are as follows:
- Finish the sensor project (or at least the width sensor) and see if its due to variances in filliament width
- Finish the belted bondtech standard filliament extruder to see if this is a filliament feed issue
- If that doesn’t fix the issue, build a pen plotter insert with 3 pens in a triangle shape around the center of where the nozzle would be and an automatically raising writing surgface of some sort to see if the motion path through corners is accurate and precise on each pass
- Get a high speed camera to see what the hell is actually going on (the cheapest possible option of which seems to be about $170…)