MK3S+ @ 0.8mm Nozzle  

RE: MK3S+ @ 0.8mm Nozzle

This is the finish surface of the lid. Any idea what's going on? What are the problems called? Under extrusion? What is the smudging called? Is there an overlapping issue? Im sadly not familiar with the terms and I dont have the experience to identify the issues.

Thank you

RE: MK3S+ @ 0.8mm Nozzle

I have one Mk3S+ set aside to print nothing but one specific object with the 0.8mm nozzle. What you've got looks pretty close to what you should expect from a large nozzle, especially with PETG.  I would perhaps take down the extrusion width on the top layer a bit, and you can adjust the infill/perimeter overlap to see if you can improve those overlap areas. 

Textured sheet. I assume you have recalibrated Live Z for the textured sheet? It's about 0.4mm thinner than the smooth sheet so you'll have to take your Live Z down by about -0.400 (more negative). Also, give the sheet a good scrub with dish-washing liquid and hot water. With a small object like this you shouldn't have adhesion or warping issues with the textured sheet (unlike the one I mentioned before which will pull the sheet off the magnetic bed unless I secure it with binder clips ☹️).

You could also try to let speed be driven by maximum volumetric speed, by setting speed values to 0. In my example I was able to cut print time by half that way. But for the object in your picture it may not give you as much as you don't have long straight moves that allows the hotend to get to max speed. 

RE: MK3S+ @ 0.8mm Nozzle

Thank you so much for your help. Im trying to chase down the problems and adjust them accordingly!

I would have 3 questions tho.

q1. How do I adjust the extrusion width on the top layer?

In print settings, Layer and perimeters I found the number of solid layer but not the extrusion width of the top layer.

q2. Where do I adjust the infill/perimeter overlap?

q3. I printed the entire object (a tube) in 0.8mm at 15% infill at 0.8mm (286g) and at 0.4mm (163g). I tried reducing the infill to 2% @0.8mm but that only reduced it to approx 240g. There is no way to further reduce the weight/usage of material @0.8mm? right?

Thank you for the help!

RE: MK3S+ @ 0.8mm Nozzle

Your perimeters, top and bottom layers add to the overall weight. 
If you have 2 perimeters with a 0.4mm nozzle your wall thickness will be 0.9mm
If you have 2 perimeters with a 0.8mm nozzle, your wall thickness will be in the region of 1.9mm so the 0.8 nozzle cube will be much heavier

if the layer height is the same for both nozzles is the same, then your top and bottom layers will weigh the same as each other, 
However if you use the maximum layer height for the 0.8mm nozzle the top and bottom layers will again be much heavier. than the o.4mm nozzle ones.

Extrusion widths  and overlap, are set, in Print Settings>Advanced (But you need to be in advanced, or expert mode, to see them)

RE: MK3S+ @ 0.8mm Nozzle

First make sure you are in Expert Mode so all settings are visible to you.  The extrusion widths are in Print Settings>Advanced>Extrusion Width
Infill <> perimeter overlap is in the same tab, so Print Settings>Advanced>Overlap
 For future reference there's a search function built into PS.  You can search for settings and it will list them and take you directly to them.

From your initial pic I would say the top layer is over extruded, not under.  This is quite common with PS unless your filament is tuned properly, even with a 0.4mm nozzle.  Look at the curved sections, top and bottom of the pic, looks very rough and will ridges in the top layer.  Thats too much plastic in the space.  The 0.8mm is making it more noticeable.  The gaps on the bottom edges of the bar across the middle is just the gaps in the pattern of trying to fit a zig zag in there with a round bead.  If you are also using 2% infill like you say I would suspect that the top layers are sagging and not adhering to the perimeter there which is leading to that area having the issue too.

Without the project  to study in detail its hard to tell for sure though.  Thne project would also help us to check for various options to reduce filament usage if possible too.  Save using File>Save Project as then ZIP it up and attach it to a reply.  Must be zipped or the forum just wont attach it.  No warnings, it just wont.

RE: MK3S+ @ 0.8mm Nozzle

q3. I printed the entire object (a tube) in 0.8mm at 15% infill at 0.8mm (286g) and at 0.4mm (163g). I tried reducing the infill to 2% @0.8mm but that only reduced it to approx 240g. There is no way to further reduce the weight/usage of material @0.8mm? right?

 

You're not going to get a lot of mileage weight-wise out of reducing infill. You can sure shave a few grams off but for many models the perimeters will be driving the weight. On the other hand, 2% infill is going to give you bad flat surfaces like that center bridge in your photo because there's not enough support to keep the surface from sagging. You could add more top surfaces but then again, that will work against you weight-wise. For a flat surface like that I may go to at least 15%, maybe 20% infill. No need to do it for the whole model though, you can use a modifier to do it just for that area. See https://help.prusa3d.com/article/modifiers_1767