PrusaSlicer 2.9.1-alpha1

PrusaSlicer

Summary

This is the first alpha release of PrusaSlicer 2.9.1. This release introduces new algorithm to detect collisions during sequential printing, multi-material interlocking, and many bugfixes - mostly of older bugs.

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.

Arrange for sequential printing

We are introducing a completely new algorithm to detect collisions during sequential printing. But not only that by far. We have actually made a new arrange algorithm that automatically positions and orders objects in such a way that collisions are avoided. Using sequential printing thus becomes safer and very easy to setup.

Just to give some context, PrusaSlicer allows sequential printing of objects (Print Settings -> Output options -> Complete individual objects) for very long time. This approach has both pros (less travels and stringing, smaller cost of a print fail) and cons (possibly longer print time because of cooling-related slowdown). However, printing objects sequentially also means that the print head has to travel downward after an object is finished, which opens a possibility of a collision with another object printed previously.

Until now, it was up to the user to decide whether current positioning and ordering of objects will lead to such a collision or not. While PrusaSlicer had a very crude check for collisions and while it showed outline of the extruder clearance area in the scene, it was quite misleading and giving extreme amount of false positive detections, rendering it hardly usable.

These times are now gone:

In addition, 3D model of the extruder is rendered when browsing through the Preview using the horizontal slider (as seen above). This is to help the user asses the situation. When a collision is detected, an error message is shown informing the user about which object was crashed into. The error does not block export of the G-code.

As of now, the feature is only provided for Prusa printers (except MK2 and HT90, the latter of which will be added before 2.9.1 final), because it requires detailed information about the extruder geometry. Printers by other manufacturers may be added later, if we are provided with the necessary data by the community. The exact format of the data may still change at this point (in general they are reasonably simple sets of extruder slices in heights where they change significantly plus the model for visualization). Testing and collecting feedback on the function as a whole is a priority at this point.

When PrusaSlicer does not have this extra information, it falls back to a very simple generic model based on extruderclearanceradius and extruderclearanceheight config options. These options are in slicer for years and were used for the crude sequential printing check, we decided to keep them for this single purpose. The values were moved from Print Settings to Printer Settings, as they describe the physical geometry of the printer. The "fallback" model used for the algorithm is seen on the picture below, printing MK4 parts on an Ender:

arrange_generic

Note that the horizontal slider has two modes - it can either browse through the whole print, or just the top layer. For assessing sequential printability, the first mode is probably more useful. The switch was in Preferences, but we have now also duplicated in it the slider settings menu in the bottom right corner, so it is readily accessible:

horizontal_slide

The algorithm heavily relies on z3 solver ↗. Thanks to Microsoft ↗ for developing the library and releasing its source code publicly.

Related to #1052, #1095, #1662, #6474, #7787, #8948, #10216, #10709, #11834, #12592, #12815 and possibly others.

Multi-material interlocking #11588

Printing with multiple materials is often challenging regarding proper connection between adjacent parts. Especially some materials do not bind well together, meaning that the boundaries form weak spots in the resulting print. The same problem (to a lesser degree) affects prints with multiple extruders of the same material. To alleviate these issues, PrusaSlicer now has an option of interlocking the neighboring parts together:

interlocking

The option can be turned on in Print Settings -> Multiple Extruders -> Advanced, where one also finds a couple of related parameters.

The feature was originally developed in Ultimaker Cura ↗ and it was later ported into OrcaSlicer ↗. The implementation in PrusaSlicer was ported from there, with only minor modifications. We would like to express our gratitude to everyone involved in the development of this feature.

Configuration options to simplify printing with different materials

While PrusaSlicer in fact supports many scenarios in multitool/multimaterial printing, it was never very user friendly to set everything up in the user interface. In 2.9.0-beta1 ↗, we introduces an additional config option to help setup printing with multiple nozzle diameters. In this release, we are adding a similar tool to help with bed temperatures. The bed temperature is defined in Filament Settings, and it is not intuitive to see what happens if two filaments with different bed temperature in the config are used.