Issue with Cura coordinate system

[leotssr 0]

 

Hi everyone, 

 

I am currently involved in a research project aiming at developing an algorithm allowing to convert an stl file into a hybrid G-code file generating additive manufacturing and machining trajectories. This algorithm is implemented as a plugin in the open source Cura environment. Unfortunately, difficulties are encountered when it comes to adjusting additive and drilling tool paths.

In our algorithm, the STL file is first turned into an additive Gcode with Cura. Then the same STL file is sliced and an offset contour is generated on each layer and turned into Gcode commands. Finally additive and milling paths are combined into one single Gcode.

The main problem comes from this last step. Indeed, when the STL file is imported in Cura (first step) the center of its coordinate system seems to be modified in order to place the part in the middle of the bed. We don’t know what transformation is applied to the part. If you have any idea please contact us,

 

Thank you very much

 

Léo

[Cuq 198]

You can try with : 

node.getWorldTransformation().getData()

 

 

But not sure you get what you want . In this case it's the Transformation comming from the 3mf file, With a Stl As you have notice it will gives you  :

 

[1. 0. 0. 0.]
[0. 1. 0. (height/2)]
[0. 0. 1. 0.]
[0. 0. 0. 1.]

 

 

 You can Also Try SuperSlicer As Free Source Code . It already integrate a Slicer + an integrated Function to generate the milling Toolpath : 

 

 

Again not exactly your request but a good start for this type of project with some interesting option like the milling_extra_size to add some material to the shape to be sure to get enough material to be milled .. 

 

[leotssr 0]

Hi Cuq,

 

Thank you for your very detailed answer.

 

The  function

node.getWorldTransformation().getData()

has indeed return the matrix you showed us. Unfortunately it only correspond to the placement of the bottom of the part on the bed. 

 

We tried to use the centroid and masscenter functions of trimesh in order to try to place the center of milling coordinate system at the same position as the one of the additive coordinate system. With no success. 

 

When it comes to SuperSlicer, it is what we are trying to do in smaller proportions ^^

 

Thank you very much,

 

Léo

[Phil0110 0]

It sounds like you're having some difficulties with adjusting additive and drilling tool paths in your algorithm for converting STL files into G-code. It's possible that the center of the coordinate system is being modified when importing the STL file into Cura, but it's unclear what transformation is being applied.

[Cuq 198]

For me there is no problem just a misunderstanding of the concept of origin and origin offset on CNC machine.  By using the origin setting in the center of the bed in Cura the problem should not exist. But since I still didn't really understand what was wrong with the Cura coordinate system question, maybe I have a wrong idea of the problem.

Edited March 30, 2023 by Cuq