Diagonal bridging issue on roller coaster track

[coaster_llama 0]

Hello!

 

I'm printing roller coaster track I've created in SolidWorks and am having trouble bridging the top diagonal sections due to the way Cura is slicing the first skin layer on the bridge.

 

The part shown is a small test printing section of the full sized component so that I can dial in settings like this before printing all of the track sections. Some of the full-size sections are curved, hence why I'm orientation the part sideways. The print time of the full sections is reduced from 30+ hours (oriented vertically with support material supporting the track arc) to 13 hours when oriented on its side. That's why I'm really trying to make bridging work here.

 

I've dialed in my print settings for bridging and have gotten desirable results.

 

When I slice my part, the first layer has good bridging in the X & Y directions, but when it goes for the diagonal beam, it prints the boarder first, leaving two corner sections mid-air (which isn't supported/connected to anything) and causes stringing for the first few layers. I did a full size print (prior to calibrating bridge settings) and it took a very long time to clean up the stringing on the print.

 

The obvious solution here is to add supports, but my experience with cleaning the stringing on the print makes me really not want to deal with that for the 20+ track sections on this build. Support on all bridges would be difficult to take out as it's very tough to reach the inside with the diagonals getting in the way.

 

Is there any way to modify the first skin layer of the bridge so that the diagonal corners parts are not midair? Something like connecting the skin layer to the vertical supports or something like that?

 

Edit: I have added the STL file to the part. Also, I am not looking to modify the part itself, just the slicing/print settings.

 

Any help here appreciated!

Edited March 1, 2020 by coaster_llama

[burtoogle 514]

Hi, I worked on the Cura bridging and would like to help. Can you please attach that small model to this thread so I can play with it! Thanks.

[burtoogle 514]

BTW, an obvious simple tweak would be to make the bottom of that diagonal strut a little higher (say, a couple of layers thick)  than the other struts that go NS and EW. That way, those NS, EW struts will already be there when the diagonal is started so its ends should attach OK.

[coaster_llama 0]

Here is the STL file for the test track!

Test Track 4cm.STL

[burtoogle 514]

I have modified my Cura to extend the bridge wall lines when they end above air. Here's the relevant layer from your model...

 

 

I am just printing a sample of that and it looks OK so I will put this new capability into my next Cura release.

 

You can find my releases at https://www.dropbox.com/sh/s43vqzmi4d2bqe2/AAADdYdSu9iwcKa0Knqgurm4a?dl=0

 

Please read the README.md file there for more info.

[coaster_llama 0]

Great! Thank you for hopping on this. I will update the thread once I print with these settings and see if this resolves the issue.