First layer under-extrusion, only in the center of the bed
My first layer shows good extrusion on the edges of the bed, but under-extrusion in the middle.
Left side of the above:
Center:
The right side is similar to the left side.
I've tried with other prints, this always happens in the center of the bed (I have bad adhesion in the lower left corner too, but probably unrelated). Using 3x3 mesh leveling, soon trying 7x7.
Adhesion seems ok, but I am not ruling out that the plate wouldn't be flat. Bed level correction does not allow me to bump the center though, only tilting.
I have a reverse Bowden installed on the machine, although not used for the pictures above. I *think* the reverse Bowden setup makes this better, although still not good.
I've tried tightening, and loosening the idler screw, but noticed no change. I understand that the rocking left and right of the extruder in X varies the tension of the filament, but I suppose that would cause under-extrusion on edges rather than center. The fact that the reverse Bowden tube seems to help is a bit suspicious though. This could be anecdotal.
I guess I could generally be a little closer to the bed, but adhesion is good (even on the under-extruded patch):
I am at a loss, please help if you can?
MK3S+ with Prima Select PETG on the stock textured sheet. PrusaSlicer-2.5.0-alpha3's Generic PETG profile.
RE:
Well, what do you know, 7x7 mesh leveling with magnet compensation did the trick.
As far as I understand, no leveling data is saved to EEPROM. Is there any way for me to go back to 3x3, while using the 7x7 data as a baseline without actually running it every time? It's a bit lengthy and I often need to baby sit the printer until after the prime line (or rather after the skirt, actually).
The Marlin documentation mentions M500 and M420 S1, would that be applicable to the MK3S+?
RE: First layer under-extrusion, only in the center of the bed
[...] As far as I understand, no leveling data is saved to EEPROM. Is there any way for me to go back to 3x3, while using the 7x7 data as a baseline without actually running it every time? It's a bit lengthy and I often need to baby sit the printer until after the prime line (or rather after the skirt, actually).
The Mk3 repeats leveling at the start of every print. However, there is an option for fast probing that you can set. 7x7 mesh bed leveling takes around 40 seconds with this enabled. It seems forever, but it's worth getting the best results possible before starting a multi-hour print.
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He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE:
The Mk3 repeats leveling at the start of every print.
Oh, I thought you could turn that off, you can't!
Can you guide me to the fast probing option, I don't find it?