PrusaSlicer 2.4.0-alpha3 is out  

@towlerg

Thick Bridges (off) is the default setting, you would have to turn it on to get the old behavior.

It still needs work, but it is an improvement when used with supports.

Regards

Swiss_Cheese

I will check

I will check, but I did not turn it on.  

Tooltip?

Swiss, tooltip must be wrong. It would make sense to default to on because that was always the behavior untill 2.4

Thick Bridges

Where is that (Thick Bridges) set?  I do not see that as a setting.

Posted by: @swiss_cheese

@towlerg

 

Thick Bridges (off) is the default setting, you would have to turn it on to get the old behavior.

 

It still needs work, but it is an improvement when used with supports.

 

Regards

 

Swiss_Cheese

Print Settings>Layers and Perimeters > Quality>Thick Bridges.  Does default to Unticked which is a change to the old as in effect if you slice with 2.3.x or lower its always the equivalent of thick bridges = on.

For the sake of undertanding

@towlerg

Bottom layers bridges

PrusaSlicer is based on the pioneering work of Alessandro Ranelucci and the RepRap community on the Slic3r project. As already mentioned above, the project was started ten years ago and a lot has changed since then indeed. The 3D printers are no more a rarity, ABS is not the only filament, motion systems are accurate and extruders are no more leaky. Thus adjustments to the slicing algorithms are called for.

Slic3r's strategies of FDM supports and object over support differ from the other FDM slicers. Namely, Slic3r was designed to make use of FDM bridging capabilities to circumvent the necessity of supports. And printing bridges with ABS was not that easy: The bridges were reliable only if extruding thick strands. Combining the thick bridges with supports required the 1st layer objects being printed thicker than the other layers, leading to ugly object undersides.

All the other FDM slicers evolved differently: The first layer over supports is printed with the same flow as the other layers, thus the first layer over supports looks nicer as long as the strands bridged reliably or supported by a support interface. For support materials that do not bridge reliably, dense support is required for high quality of objects over supports.

Starting with this release, PrusaSlicer newly offers printing bridges and 1st object layers over supports with the default layer thickness. The bridging behavior is configurable with a new "thick_bridges" boolean option. If enabled, the old Slic3r bridging strategy is applied, while if disabled, bridging is performed in a similar fashion to the other FDM slicers, leading to better bottom quality over supports. With "thick_bridges" disabled, the behavior of "bridge_flow_ratio" changes: Instead of modifying cross section of a rounded extrusion while keeping the gap between the extrusion threads constant, extrusion spacing is maintained while modifying the extrusion width and / or height to reach the prescribed extrusion ratio.

This is the link to the entire article.

https://github.com/prusa3d/PrusaSlicer/releases/tag/version_2.4.0-alpha1

Enjoy

Swiss_Cheese