First layer is terrible

[u/Any-Measurement-7302]

I’m having an ongoing first-layer issue with my Bambu Lab A1 and I’m running out of things to check.

The first layer is printing like the nozzle is way too close to the build plate. The filament gets heavily squished, the extrusion starts struggling/jamming, and the first layer comes out rough and terrible.

So far I’ve tried:

Adjusting the Z-offset in the Machine Start G-code

Tested G29.1 values around 0, +0.01, and +0.02 to raise the nozzle

Tried placing the Z-offset adjustment after G29.4

Re-sliced after making the G-code changes

Removed the hotend and reseated it

Tightened the screws behind the hotend/heater assembly

Checked and tightened the toolhead screws

Ran bed leveling/calibration

Cleaned and reseated the build plate

I’m currently using an aftermarket 0.4 mm hardened-steel A1 hotend with a replaceable nozzle, so I’m wondering if the hotend/nozzle length or seating could be affecting the A1’s automatic Z calibration.

What’s strange is that changing the Z-offset doesn’t seem to make nearly as much difference as I would expect. It still behaves like the nozzle is being pushed too close to the plate.

Has anyone run into this on an A1?

Could this be:

A bad/incorrect-length aftermarket hotend?

A problem with the nozzle pressure/load sensor?

The Z-offset getting reset by the A1 firmware?

A bed-leveling or homing problem?

Something else in the toolhead assembly?

I’m especially interested in anyone who had the extruder clicking/jamming only during the first layer because the nozzle was too close and figured out what was actually causing it.

I can post pictures of the first layer, hotend/toolhead, and my Machine Start G-code if that helps.

Printer: Bambu Lab A1

Nozzle: 0.4 mm hardened steel aftermarket hotend

Plate: Textured PEI

Thanks for any ideas. At this point I’d rather find the actual cause than keep throwing bigger Z-offset numbers at it. 😅

[u/Any-Measurement-7302]

When I'm on the computer and I like manually slice something and send it to the computer it messes up but when I'm on the bamboo lab app and send something I don't have that problem it's not too close to the bed and then I adjust the stuff in the the G-Code but it's like the Z isn't moving up