Top layer not totally plane  

RE: Top layer not totally plane

This looks like a problem coming up from the bottom layer; I see things that look like your first layer is too squished (Live Z too negative). Especially with thin parts, those things can continue to manifest and show through to the top of the print.

Is there any infill in between the top and bottom solid layers? That can help buffer these sorts of things, but also cause them if the infill is too sparse (aka "pillowing").

Post a picture of your first layer of the print. I strongly suspect we'll find the answer there. 

Make sure to use this method if you do any adjustments to your live Z, it is far easier to get right than the built-in method:

https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/life-adjust-z-my-way-t2981.html

RE: Top layer not totally plane

Big flat parts,

use glue stick,

use a big brim attached to model, 4 or 6 lines,

Speed, infill speed of 200mm is to fast, go to 150mm,(or slower),

Temps, because a big flat model has a high speed, do a higher temperature(with 200mmm speed i had to do 20 degrees higher )

slower print speed in general.

Of course, keep bed clean, and first layer perfect.

RE: Top layer not totally plane

Pictures of my test squares. All over the top looks the same.

RE: Top layer not totally plane

Again, please post pictures of your first (bottom) layer. You also didn't answer my question.

RE: Top layer not totally plane

if the top layer is rough, on a tall print, the cause is often caused by over extrusion. reducing the extrusion multiplier in slicer, or reducing flow  on the LCD...

regards Joan

RE: Top layer not totally plane

An FDM printer prints plastic in linear tracks.  You will see these tracks, and depending on how well you have tuned the extrusion rate, there will be FDM related artifacts.  The top surface will never be a true flat as if the part were molded.  Nor will the sides ever be truly smooth. 

The visual effect of printing in tracks also may incur pigment density issues, where due to flow rates and temperatures pigments settle and make one side of the track more colored, leading to a visual stripe that isn't related to the printer.  I've printed some Prusament filled filament that has shown that attribute: the gold fill floats to one side.

I think you should explain what your expectation is rather than show a part that - to me - looks perfectly fine.

RE: Top layer not totally plane

Tanks for all your reply.

Vintagepc: There are no infill un this Print, I will Print a first layer test this week end i’m not at home this week.

peter-m26: The print speed for the top layer are 40mm/s and no problem with the print adhesion only with little pieces and I add a brim and it will stick.

joantabb: I Think not that is a over extrusion problem there are little gaps in top and bottom layer but no line on the side of the printing.

Tim-m30: Before to print with the prusa I print with a Creality and the top layer never look like that. I know FDM can’t be prefect flat but I Have already printed stuff with better top layer quality.

RE: Top layer not totally plane

Speed off infill i mean, this is normally 200 mm, this will fill in the big parts, if this goes wrong, then your top layer will be bad.

You can test this, i tested with more then 1 filament and had on 200 mm always problems that filament did not melt enough, with 150 mm it was ok, or 20 or 30 degrees higher temperature helps.

Also if your model warps, then your top layer will go higher, and you nozzle will hit it, and the new filament

will be to low and hit the older filament.

RE: Top layer not totally plane

If you want it smoother, search for ironing with program cura, you can make it smoother, if it is easy i do not know.

RE: Top layer not totally plane

There are rare cases when the nozzle and heater block are not perpendicular to the bed due to a bent heat break.  Generally caused by attempting to remove the nozzle when cold.  A full hot end disassembly is required to check this.

A closer look at your prints: it looks like you are printing too fast and getting under extrusion.   What speeds are your perimeters and top layers set to?  

RE: Top layer not totally plane

Sorry I'm not home for the week, thank you for your's reply

I Just print 4 square (PLA.gcode) from https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/#_ga=2.8200370.1026174211.1560071402-81779572.1559376261

And I don't know who is the problem because the first corner printed was not good every time the printer start I-on bottom right

RE: Top layer not totally plane

My previous setting was -650

I thought the setting -700 was good but the whole square -700 leaves me septic

RE: Top layer not totally plane

Are you using the 7x7 mesh bed level or just the 3x3 default?

7x7 is better.

Also - if you see variation in test results run to run, try adding the M860 S35 command to your start up gcode:

Just before the G80 command:

; soak PINDA then level
G0 X50 Y50 Z0.15 ; this is a good PINDA heating position
M860 S35 ; the new code - wait until PINDA is >= 35C
G80 ; mesh bed leveling

RE: Top layer not totally plane

Clean your bed you can try, looks like it is coming loose.

Wash with dish soap with nothing extra inside(concentrated is the best).

Then clean with alcohol.

Try again,

then lower the z-layer step by step, check that you do not go to low, it will crash into the bed.

Also try with different filament.

Slower first layer could help, or more heat during the first layer, glue stick could help, these 3 I normally do not use.