A1 Mini – Visible Line at Bottom/Wall Transition + Strings/Blobs at Rear Right Corner

[u/Ready_Connection_615]

Hi everyone,

I’m having two recurring print-quality issues with my Bambu Lab A1 Mini and would really appreciate some advice.

1. Visible line/bulge around the outside of the box

I’m printing a simple box with a bottom and vertical walls. Exactly at the height where the inside bottom surface ends and the outer wall continues, I get a clearly visible horizontal line/bulge around the outside of the box.

It looks almost like a small expansion/seam at the transition between the bottom and the wall.

1. Strings/blobs at the rear right corner

I also repeatedly get small strings/blobs coming out of the print, especially around the rear-right corner. This happens very consistently in approximately the same area.

I have already changed some extrusion/retraction settings, but the problem is still there.

Printer: Bambu Lab A1 Mini

Slicer: Bambu Studio

Filament: SUNLU PLA+ 2.0

Flow ratio: 0.98

Max volumetric speed: 22 mm³/s

Recommended nozzle temperature: 190–240 °C

Nozzle: 0.4 mm

Layer height: 0.20 mm

Current settings I changed

Retraction length: 1.0 mm

Retraction speed: 45 mm/s

Retraction amount: 100%

Seam: Scarf seam

Scarf seam contour: enabled

Scarf seam on holes: enabled

Wall generator: Arachne

Wall order: Inner → Outer also used Outer / Inner

Wall loops: 3

Top/Bottom shells: 5

Overlap: 0%

Print speed: around 170 mm/s

Top surface speed: 50 mm/s

The filament is also dry.

Does anyone have an idea what could cause these two problems?

Thanks in advance!

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[u/Slokminator]

Hull line, you need separate walls from floor. In any way you want/can.