Need to reduce stringing and get bridging as good as possible

[player879 0]

I am attempting to print a whistle, specifically a slightly modified version of https://www.thingiverse.com/thing:2981309 Inside the whistle are small air chambers that need to be as smooth as possible. My main issue is that Cura will sometimes make a travel across the chamber, risking stringing which can mess up the airflow a lot, when Cura could just have the nozzle go around the chamber to the other side. I have messed with the "combing" setting in travel, and it makes a lot less travels across the chamber, but there are still some. Additionally, most of the travels it does make are with retractions, which reduces filament flow, but every once in a while there will be a dark blue line instead of a light blue line, signaling that the nozzle will travel without retracting. I also have a less significant issue with the top of the chamber sometimes sagging. It is mostly fixed with the experimental bridge settings though. I am asking to see if anyone has had similar issues with Cura not going around, or not retracting, and how else I can reduce stringing as much as possible. I also increased the travel speed, that made it worse, so I'll probably decrease it to solve a lot of it.

[burtoogle 516]

Please save the project (File -> Save) and attach the .3mf file to this thread so we can see the settings you are using. Thanks.

[player879 0]

Here's the 3mf file, sorry it took a while I had a few days in a row where I had no time to do this.CFFFP_whistle insane quality.3mf

[burtoogle 516]

Hi, thanks for the file.  Using the no-skin combing mode should avoid any un-retracted travels over air.

 

This model is difficult to print well as it is because it has a curved wall on layer 88 that should be supported but it isn't recognised as a bridge because the individual line segments are shorter than the minimum bridge wall length. Even if you reduced the min bridge wall length it still wouldn't print well because bridge walls have to be straight lines, you can't have an unsupported curved line! The best solution would be if the model itself provided support which could be removed after printing.

[gr5 2,224]

In my experience white filaments (regardless of brand) string more.  A lot more.  I found this is true for PLA and also CPE.  So my advice is to avoid very light colors like white and light yellow.  Orange and other slightly darker colors seems to print fine without any stringing.