Strange pattern on first layer (new MK3S)  

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martin.d17
(@martin-d17)
Trusted Member

Newly assembled printer, did first layer calibration. Printed Prusa logo, looks ok. Tried to print my model, and top layer is bad, gaps and scars... Tried to print something with bigger surface and first layer looks like on pictures, strange patterns with gaps (underextruding?) Then I reset printer to stock, calibrated first layer again, and printed the stuff.. The same (picture2) happens - strange patterns with underextruded parts.

Anyone know what should I do?

 

Posted : 04/07/2020 11:19 am
peter.m26
(@peter-m26)
Honorable Member

Make pictures wen filament is printed on the bed, then we see more.

In the settings of the printer choose 7x7 bed leveling.

You could be to low, try a little higher, normally gabs is high, try first higher and if you see you are to high, do little steps lower until it is OK.

Clean bed with dish soap, then print.

Posted : 04/07/2020 4:55 pm
martin.d17
(@martin-d17)
Trusted Member

Thanks for the tip, this is the lowest Z I can have otherwise the result is worse. 

This is one layer surface printed, you can see at the borders it prints nice layer, at the bottom right corner there are waves (which means too low Z). In the middle there is strange pattern of filament where I think is underextruded. Kind of strips about 3cm wide. Question is why are there patterns.

 

Closeup:

Posted : 05/07/2020 5:05 am
peter.m26
(@peter-m26)
Honorable Member

7x7 bed leveling, do you have this set in the settings?

Clean bed with dish soap, if you have filament on first layer that is lighter(white) normally this means it is not sticking enough.

Lines of the first layer should be touching, in the picture I would say go lower.(or not enough of filament is coming out of extruder).

One test you can do, move extruder 100mm high, then extrude by hand, see if you have bubbles(water in filament), and it should go straight down, and most important it should be thick enough. You could have a partial clog.

Most important for printing is:

Clean bed, sticking will be good.

First layer should be 100%, then sticking is also good.

Look at the movie again for first layer calibration.

Then for future, start print, look at the first line, adjust z-layer(if needed), after the first layer is done,  look at first layer if is OK and sticking enough(no big white spots), this helps also to prevent a big ball of filament sticking to extruder after the print is ready.

Posted : 05/07/2020 8:25 am
martin.d17
(@martin-d17)
Trusted Member

@peter-m26

Thanks Peter for your help, I have 3 prusa printers at home all were kits, this is the newest. 

I used 7x7 matrix bed leveling, this picture is taken with it, bed was cleaned thoroughly with dish soap, first layer is ok, issue is that the extruder is somehow doing issues, pushing less material as it should, I dont know the reason. PLA I am using is brand new 1month old (due do date of produce) Hotend is totally clean, not clogged, I also replaced the nozzle with other. There is no leakage anywhere on hotend. 

I repeat what is strange, there are strips of exact same sizes where issue is and filament is underextruded, must be a reason for that.

Posted : 05/07/2020 8:36 am
peter.m26
(@peter-m26)
Honorable Member

Check with a straight piece of meta of bed is flat.

Play with de extruder springs, check manual how to, and try holding a little more, also take a look at gears if they are OK.

Posted : 05/07/2020 9:25 am
peter.m26
(@peter-m26)
Honorable Member

Do a test if your extruder moves 100mm, mark your filament and move it, and see if the moves enough filament.

Posted : 05/07/2020 9:47 am
martin.d17
(@martin-d17)
Trusted Member
Posted by: @peter-m26

Do a test if your extruder moves 100mm, mark your filament and move it, and see if the moves enough filament.

I dont really understand this.

Posted : 07/07/2020 7:34 am
peter.m26
(@peter-m26)
Honorable Member

@martin-d17

Make a mark on your filament 0mm , mark 100mm and 110mm another two marks.

Now extrude 100mm filament, then measure where the lines stop, between 100 en 110, it should stop at 100, then you see if something slips in your printer.

Search with google how to calibrate your printer or extruder.

 

Posted : 07/07/2020 7:59 am
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