How to avoid bumps that are produced by stuck/glued strings when a relatively big empty space is covered?

How to avoid bumps that are produced by stuck/glued strings when a relatively big empty space is covered?  

Active Member


I have a strange problem when printing flat surface using Prusa Mini that is 4-5 layers above the heat bed using PrusaSlicer 2.2.0 (latest one).

For example printing the “Stackable Battery Holders” ( ) the A2 part:



I placed the part with the letter A towards the heat bed in order to flawlessly print it. Using PrusaSlicer until layer 5 there is an empty space below the A letter. I tried all type of support including manual ones but PrusaSlicer does not want to put any under the letter A as it thinks that they it is not necessary at all.

On the real print when layer 5 starts covering the empty space below the A letter (as seen on the attached layers picture) during the first 4-5 diagonals the strings stuck/glued together thus making a bump and then a distance between them and the next stings on the same level – I showed this on the attached drawing.  On the next layer 6 the nozzle started dangerously and loudly bumping when passing over bump. I think this is not expected behavior.


My question is how to avoid this type of unexpected bumps?!?



This topic was modified 1 week ago 2 times by sth.udoma
Posted : 16/09/2020 8:24 pm
Illustrious Member

The blue lines are bridging. Try toggling Print Settings->Layers and perimeters->Quality->Detect bridging perimeters.

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Posted : 16/09/2020 9:48 pm
Active Member

It was set during the print. Should I un-check it?

Posted : 16/09/2020 10:25 pm
Active Member

I tried  Print Settings->Layers and perimeters->Quality->Detect bridging perimeters both checked and unchecked and there was no difference at all - every time the strings over the bridge join and form a bump. How could I print this while PrusaSlicer does not let me put any support there?

Here is a simple 3MF file with just this part. It should be print with the latter A facing toward the heat bed.


This post was modified 6 days ago by sth.udoma
Posted : 18/09/2020 11:14 pm
Noble Member

If you want to put support there you can turn OFF the option called don’t support bridges. 

Posted : 18/09/2020 11:45 pm

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