Unresolved Filament issue or printer issue?

My first suspect would be a small amount of over extrusion. Did you calibrate the eSteps?

 

They have no clue, 800 or more is more in line with what it should be. Also 20 mm/sec is a bit slow for PLA. They pulled 723 out of you know where! I thought Cura could control line width, which is essentially the same as extrusion rate. I could be wrong as I haven't used Cura in so long.

 

Unlike steel or metal gears the plastic ones used in the extruder are not dead on a given spec
There can and will be some variation.

 

I wonder if those are the layer start points?
If so some extra retraction might be needed. It could be carrying a small gobbet of filament around that it deposits on the start.

Look here (Ooze Controls section):

https://jinschoi.github.io/simplify3d-docs/

 

Let us know. That is an interesting defect to be caused by filament. I have not seen that before, but I can believe it. If it were a bit wet (absorbed moisture) you will get some surface bubbling. Normally doesn't look exactly like that though,

 

My suggestion still stands. Calibrate the extruder first. Otherwise you are just chasing your tail trying to fix anything else.

 

You response to my suggestion is in direct conflict with your post #3 and post #6. So what is it, 850 or 723? Please if you want help, clarify this. If Marlin doesn't know what it is extruding there is no way for the slicer, no matter which one you use to be accurately set for multiple styles of filament or multiple nozzle sizes.

 

Numbers higher than 800 for the eSteps are not uncommon when you actually calibrate the extruder.

 

Please note this property of plastic filament, it does not come out of the extruder the same as it goes in! PLA for instance expands quite a bit when heated, ABS actually shrinks in volume as it cools (that is why it tends to warp), other filaments react in other differing ways. The point is that if you ask for the extruder to spit out 100 mm of filament it need to spit out 100 mm of filament. Sorry but 723.32 eSteps just doesn't do that. You are also confusing, and you are not alone in this, software settings with hardware capabilities. This is perpetuated by companies that use arbitrary scales based on first generation mechanics that inflate numbers like extrusion multipliers and the like. So what I am saying is that your slicers 100% extrusion multiplier is not 100% but actually more based on assumptions made on early open-source designed printers.

Bottom line is that you need to adjust the slicer settings to make sure they are extruding the exact amount of plastic the printer is designed to extract. That is the only way to insure that you will not have to make a whole mess of adjustments every single time you change rolls of filament or you move from brand to brand. We have pretty good precision with the Robo, but what we need is accuracy. this is what mechanical tuning gives us a well calibrated (mechanically speaking) machine will perform consistently from print to print and can provide very accurate prints as well no matter what we throw at it.

I am going to jump of my soapbox now.

 

I explained precisely why that is happening with a firmware value that under extrudes mechanically in my post. I know that my printer does 100 mm when I ask for 100 mm, but in the slicer the extrusion multiplier is set to .92 for PLA, in my particular case. The .92 really has to do with the math required not the actual amount of plastic. Please remember that you are dealing with a machine, not a spreadsheet or other software only entities. Machines have physical requirements. get those correct and then all the software tweaks are only necessary to get it as perfect as you need it to be, not the other way around.