Large areas
That looks like a combination of warping and fingermarks on the print sheet. A thorough cleaning should be enough to restore adhesion.
Cheerio,
RE: Large areas
Yeah,
We often see on Facebook photos of different issues on large horizontal areas on the MK4 with and without IS. The most common one is a ringing (wave-like) pattern seen near corner areas and typically on the lower layers. Its tempting to label the areas as those where the extruder changes direction but that would be incorrect, since the areas eventually get over-printed with the next layer. I'm thinking this is a case where IS has not been applied, the developers thought only about the vertical corner areas of a print.
When I look at your photo. If this was a Mk3S+ I would be saying that your first layer needs attention, looks like over-extrusion. I have certainly seen this effect on MK3S+ printer.
But it's a MK4 with "perfect first layer", and that cannot be true. But it does looks like inconsistent extrusion. I wonder if you paid attention to the extrusion multiplier tuning which still applies to the MK4, whether you would see a benefit.
Other possibilities include :
1. Inconsistent filament diameter. So it gets a different grip on the filament as it goes through the filament feeder. But the Nextruder must be very finely tuned to have such a marked effect.
2. Possible filament dust in the feeder gear, leading to inconsistent gripping.
3. Some issue with the bed hot plate. Uneven temperature distribution. This does not seen all that likely, but its theoretically possible.
4. Filament moisture. Moisture affects the heat-flow filament characteristic. Moisture can be distributed unevenly through the filament length. So this is one of the stronger possibilities.
5. Uneven filament feed. If the roll is not rolling smoothly or there is some other factor like kinked tubing then this could cause uneven friction versus time, possibly leading to the effect observed.
6. Old Stiff/brittle filament. Leading to inconsistent grip in the filament feeder.
You could try increasing the extruder idler tension perhaps.
RE:
Sheet Is clean. No problem with no input shaper profile. First layer Is ok, problems comes with second layer.
RE: Large areas
Sheet Is clean. No problem with no input shaper profile. First layer Is ok, problems comes with second layer.