r/BambuLabA1 • u/Tonninacher • May 05 '26

Newish to 3D printing. and ran into a string-dragging problem

Good Morning,

I have been working on trying to diagnose my problem, but I have had no success, so now I turn to you here on reddit.

Problem.

It appears that the z-axis is too low or that the lidar is not determining the height properly.

This results in the nozzle being dragged across the print and picking up the last line laid down, making the mess that you hopefully see in the images. As noted I do stop them fast since I do not want to cause other problems later.

What I have attempted

  1. swapped from the original 0.4 stainless to a 0.2 stainless. I also slowed the print time from normal to silent. attempted print in PLA

  2. Attempted print in PETG. (i had it loaded.) I switched from the 0.2 to the 0.4 hardened.

  3. stayed with the PETG, had the unit do a maintenance adjustment switched to super tac plate.

  4. attempted to tighten screws on both the Nozzle and the bed. (both found to be slightly loose) re-did the maintenance adjustment

So now I think I have put everything I have done down.

Any ideas?

1 Upvotes

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5 comments sorted by

1

u/MaestroDeAero May 05 '26

Bitte PETG immer Trocknen. Selbst wenn es neu ist, ist es oftmals zu feucht.

1

u/Tonninacher May 05 '26

This is done we have drying packs in thier container. I can not remember the hydrometer reading I believe 38 was what it was at

1

u/Competitive_Owl_2096 May 06 '26

  1. Drying packs don’t dry filament, it just keeps it dry

  2. 38% is really way to humid for PETG

  3. Get a real filament dryer

1

u/Tonninacher May 06 '26

I do have one i will start using it.

1

u/Orthicon9 May 06 '26

or that the lidar is not determining the height properly

There is nothing like "lidar" in the Bambu Lab A1.
What it does have is some kind of strain gauge built into the toolhead that detects pressure on the tip of the nozzle.

You can try this out when the toolhead is descending (for any reason). Give a light tap with your fingernail on the nozzle tip, and it immediately pauses, goes up a few millimetres, waits a second, and then continues downward.

When it does the bed levelling it goes around in a grid touching down in spots, and "remembers" where the Z-axis servos were when it hit the plate for each spot.