surface spots  

RE: surface spots

I have the same problem, i think the printer moves when it begins another layer.

In an other topic somebody suggests me to check mechanical parts searching for loose belts

I think it can be also a matter of extruder inertia and i wil slow down positioning movements and acceleration

RE: surface spots

That looks like the seam has been set to random or the seam placement in a circular part is giving that effect.  Change the seam setting to aligned or rear and reprint.  If all the artefacts then line up you know its the seam then.

You cant ever get rid of it completely with fdm.  All you can do is minimise it by carefully tuning your filament settings to match that particular roll.  As each roll varies people just usually do a basic tuning for their filament average and then leave it.  Normally the slicer on default settings will try and hide them in corners but with circular smooth paths there aren't any to do that with.

RE: surface spots

the seam is indeed set to "random"

most part i print are circular and I pref not to have it aligned, is there any way to minimize this effect?

what parameter is most related to it?

RE: surface spots

So many factors effect it and I have never got rid of it.  Number one to do before anything else is to use a set of calipers and measure your actual average filament diameter at several points along a few metres, at different angles (to take non circularity into account).  Then enter that into your filament profile instead of the default 1.75mm.  This gives the slicer the most accurate chance when it comes to working out the actual amount of plastic extruded.  This step helps a lot of things overall and can result in you needing less retraction to start with.

After that then you need to start on things like retraction settings, trying with no retraction, retract/deretract speeds, wipe, try extra length on restart etc - all the settings under Printer Settings>Extruder>retraction.  You can spend days trying little changes to reduce it.  However it also seems to depend on the model too so eventually you get to a point of diminishing returns. Especially as you cant ever get rid of it completely.  And as soon as you use different filament you need to do it all again as some filaments print differently.  

I'm sure someone like Bobstro who is much more scientific about these things could give you better advice.

I now just do the filament diameter setting and stick to my usual brands when buying filament.

RE: surface spots

@neophyl

that's great, thank you so much for all the info, will try one at at time