Print Volume Verification Tool
Milestone ID: 886896
We currently have no tool to determine if a given 3d-model fits within "the print volume" of a given Hangprinter.
The term print volume is more complicated for Hangprinters than for other 3d-printers.
There exist a well defined reachable volume. It is shaped roughly like a tetrahedron, with all six edges bent towards the origin.
- The three bottom edges are bent upwards because the lower anchors need to be below the effector, to give it a downwards pull.
- All six edges bend towards the origin because of gravity. At the limit of the the tetrahedron wall, it is impossible to get an outwards pointing force or velocity, no matter how hard one tightens the lines. Gravity will pull the effector inwards until lines have sagged enough to give them a working angle. The better angle lets the lines pull outwards with a force that equals out the inward-pulling gravity.
This reachable volume is interesting, but very rarely relevant.
Most prints volumes will be more limited by lines touching the print and messing up the positioning of the effector when that happens.
Lines may crash into previously printed material, so the reachable print area at a given layer depends on the shape of previously printed layers. So the concept of a print volume exists, but it's shape is different for every print.
As long as we print in 2d-layers, we can analyze the 3d-model (the stl), by slicing it into layers.
In a more general situation where we don't print in 2d-layers, we would need to analyze the gcode directly, and consider every single move to be limited by every previous print move. Every single print move will cast unreachable "shadows" pointing from the anchor point and through the printed material.
To keep things simple from the start, this milestone only covers the case where we stick to printing strictly in layers.
We are in a similar situation as with overhangs: we need to remember previous layers, and make sure we don't mess up. In the case of overhangs, various software can analyze them and give us warnings.
We need a software that can analyze line crashes.
Before we start a print, we must get an answer to the question:
Will lines crash into the print, or not?