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Summary

This is the first public alpha release of PrusaSlicer 2.7.3. This release introduces improvements of multi-material printing, improvements of spiral vase mode and several important bugfixes.

To let you enjoy the alpha without worries, the alpha builds save their profiles into PrusaSlicer-alpha directory, so you may use the alpha side by side with the current release without ruining your production configuration. The alpha will ask whether it should import a configuration from previously run PrusaSlicer versions on the first start.

Improvements of multi-material printing

For a long time, a community-developed feature exists which claims to improve filament tips during toolchange sequences, which would in turn increase reliability of devices depending on reasonable tip shape (such as Prusa MMU1 and MMU2). This feature is referred to as "skinnydip", and the basic principle is to push the filament back into the melt zone after it was unloaded to melt off the thin string that the filament often has. We at Prusa Research have tested the feature several times, but the results were not very convincing and we never integrated the feature into PrusaSlicer. After doing more experiments recently, we found out that the technique is more convincing when preceded by very rapid ramming.

Based on that knowledge, we decided to implement very similar approach for reshaping the filament tip. Because the goal is to reshape the filament tip using the mostly empty nozzle, instead of melting off the thin filament tip, we call our approach "stamping". There are two new parameters in Filament Settings (filament_stamping_distance and filament_stamping_loading_speed) which control how far and how fast should the filament be pushed after the initial unload. The stamping moves are coupled with cooling - the stamping moves are performed between the individual cooling moves.

We would like to highlight community projects that helped us develop our Stamping step and saved our developers and testers a significant amount of time – Skinny Dip post processing script by Erik Bjorgan and Dribbling by Antimix. While we ended up with a different approach, we would like to thank both authors for all the effort invested into the project and for making it open-source! (Related to #2385, #2452, #2729, mentioning @domesticatedviking and @antimix.)

Purging volumes

PrusaSlicer allows to set purging volumes for single-extruder multi-material printers, so that each filament is purged exactly as it needs to. However, these settings were only saved in the 3MF project, not in configuration. This made setting them quite cumbersome and the user would always need to think about adjusting the default values. On the other hand, setting the values only in configuration without the option to override it in the project is also inadequate, because one may care about purging more in one project and less in another. In addition, the configuration option would make sense both in Filament and Printer Settings. #1273, #1282, #2990, #3756

In this release, two additional configuration options were added. The volume to purge is set using multimaterial_purging in Printer Settings->Single extruder MM setup. This value can be further modified on filament level using filament_purge_multiplier in Filament Settings->Advanced.

As for the project-specific override, the "Purging volumes" dialog now contains a switch. You can either use the values from Filament and Printer profiles (as described above) or define your own matrix of purging volumes (like in previous PrusaSlicer versions). When you decide to do that, the values from the configuration are not used.

Spiral vase mode improvements

When using spiral vase mode, the toolpaths are generated as usual and the resulting extrusions are then extruded while gradually increasing z. This approach led to seam-like artifacts on the print in places where the layer transitions would normally be (#4116, #2841). In addition, the last layer would end abruptly, creating a sharp "edge" where the extrusion ends.

Both these issues were addressed by @andrewboktor by interpolating between adjacent layers and by gradually reducing extrusion flow at the very end of the print. The improvement was recently merged into OrcaSlicer (SoftFever/OrcaSlicer#3091), and we got a pull request with a port to PrusaSlicer. After we evaluated the feature, we decided to merge it because it is well written, well working and very useful.

Thanks to @andrewboktor for the time and effort invested into the issue, and to both @vovodroid and @tg73 for providing a pull request with a port from OrcaSlicer (#12079, #12142).

Other improvements with respect to 2.7.2

• PrusaSlicer is now able to open 3MF files generated by BambuStudio and load geometry from them. (#10718, PR #10808, thanks to @cmguo). Please note that BambuStudio allows to save a 3MF containing G-code only, which is not supported by PrusaSlicer and loading of such 3MFs will fail.
• Metadata of binary G-code have a new item named objects_info, which lists all the objects in the print and their boundary polygons. The same info was added into the comments at the end of ASCII G-codes.

Bugfixes with respect to 2.7.2

• Pressure equalizer limits were not respected when Dynamic speed on overhangs was used (#9485). This is now fixed. Pressure equalizer is also not applied after long travels. Many thanks to @MGunlogson for providing a fix in his pull request #9622.
• Fixed a bug resulting in inadequate anchoring of bridging extrusions. This bug was introduced in PrusaSlicer 2.6.0. #10231, #11500, #11633, #11173, #11117, #9999, #10313, #11150, #10493
• When using Cancel object feature, the marks denoting where one object ends and another starts were placed incorrectly. As a result, there was a missing deretraction after all travels to objects which would normally be printed following the cancelled object. The issue was even worse with sequential printing, where the uncompensated retractions on the cancelled object summed up and could result in filament being unloaded past the driving gears.
• When arcs (G2 and G3 G-codes) were enabled, PrusaSlicer generated toolpaths outside the print area in certain cases (#12381).

Translations

• Updated POT
• Added Slovenian translation (#12422, thanks to @jernejp21)