Ultimaker
Enable Bridge Settings bad orientation
Cura Version
5.5.0
Operating System
Windows 11
Printer
Creality Ender 5
Reproduction steps
I'm trying to to use a different fan speed for bridges with the "Enable Bridge settings" feature. The problem is that the first bridge layer has bad orientation when enabling this feature.
Actual results
Bridge line direction is lenght-wise and very long
Expected results
With "Enable Bridge settings" disabled I can use Top/Bottom direction to [0] in order to get the short bridges:
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Added project file CE5_Cable Keeper (M).zip
Here is another, more obvious, example of this issue, this time from Cura 5.6.0.
Sometimes bridging is between only two walls like this, and there really is no choice about direction:
But several layers later, here is the start of another, much longer bridging:
We see here that the bridging that Cura produces is c. 50mm long onto a wall that is itself already only a single layer bridge (resting on some fairly sparse Lightning infill) rather than going in the perpendicular direction where it would be bridging over a far smaller distance (c. 15mm) and onto some pretty solid walls. Changing the infill to 0% didn't change the direction, so Cura is currently not using either the total bridging distance wall-to-wall, or bridging distance taking into account supports/infill, or the solidity of the walls at either end - it is presumably picking the start point for bridging and then going from there rather than considering the totality of the bridging.
To me it seems like the choice is normally going to be obvious to a human (and so hopefully easily turned into an algorithm):
- Choose a direction where there are at least x-layers (fixed 2? option defaulting at 2?) of wall already existing.
- Choose a direction where the length of unsupported bridging will be significantly shorter than other directions (taking into account the underlying support and not just the inter-wall distance) .
- Choose a direction that maximises the proportion that is at right-angles to the wall. (It is a bit of an edge case, but if you imagine a hollow doughnut/torus then you might even want the first bridging layer to be perpendicular to the walls all the way around i.e. radial rather than parallel.)
Obviously these rules may conflict - so there probably needs to be some sort of weighted scoring to decide whether short bridging onto a new and poorly supported wall is better than longer bridging onto a solid wall. On the whole I would think that bridging distance (taking into account supports/infill) is going to have a significantly higher weighting than whether the wall at the end (which will hopefully have cooled and solidified before you bridge to it) is solidly supported or not.
(And please, if at all possible, make the choice completely automated without any tweaking settings - there are quite enough settings already in Cura!!)
