Printing bridge over the hole

[MartinsZB]

Hi! It looks like I am setting something wrong, but I can not figure out what. I have hole in model, but when sliced it shows the bridge. But let`s the pictures talk.

STL:

Filament_Guide_PrusaSide_V2_fixed.stl

The model itself after Netfabb

(45.39 KiB) Downloaded 492 times

Before slicing:

My model

After slicing:

Sliced model

Thanks for your support!
Martins

[willnewton]

I have been having this same issue since v3 came out. No matter how clean and simple you build an item, it wants to put in a single layer bridge somewhere. I will also sometimes get very strange infills and areas that will not print at all. Files that had no problem running in V2 now do not print correctly in V3.

I have been able to "fix" it by using Microsoft's free version Netfabb online to generate a file that S3D likes.

Unfortunately, this does not fix S3D. Even worse, it makes the problem appear to be your fault due to poor CAD drafting, not S3D's file handling.

Pretty annoying bug for sure.

[MartinsZB]

This STL is "repaired" with Netfabb, but still have same problem. So I guess the problem is not in file, but in S3D interpretation.

[MartinsZB]

Ok. It must not be a file problem. It is bug in software. When I turn the object 90deg. Problem is gone.

turned 90deg and Sliced

[CompoundCarl]

The STL slices fine for me. Can you post a factory file?

[MartinsZB]

Nice! Hope to find the setting, what is wrong.

MartinsZB Prusa i3 DualExtruder_V6.fff

Factory

(24.23 KiB) Downloaded 587 times

[willnewton]

I was able to find a workaround for the problem. Try changing the layer height. I went from 0.20mm layer height (with mystery bridging and VERY ruined print in the preview) to 0.25mm (with no mystery bridging).

That, paired with your angle change should make it pretty evident that it is not a modeling issue. Something in the S3D processing is causing hiccups.

Also, for this model a Nettfabb "fixed" version did NOT remove the bridging. So that is not a sure solution either.

[dkightley]

This is one of the very strange things I've noticed with S3D. There seems to be some conflict when some feature in the model (absolutely no idea what...a node, face or edge, good or bad) falls at an exact multiple of the layer height...and S3D gets things wrong. This is obviously some form of hard to find bug in the code that occurs from time to time....the hardest form of bug to remedy. I know, having being a software engineer.

Fortunately, there's an easy way to fool the software and get round the issue - varying the layer thickness by a very small amount. Not by much....by perhaps 0.001 mm or so. This moves the layer boundary away from the problem...and all prints fine.

Hopefully, S3D support will pick up on the examples in the forum and will get an opportunity to investigate this anomaly sometime soon.

[juliezva]

I've noticed it happen on edges that have a filet on them.

[MartinsZB]

Thanks for your support! So the layer height is one more thing to thinker around