One of the benchmarks are 90° overhangs in different directions, and I printed with vertical nozzle on an ordinary 3-axis FDM printer, therefore I prepared the G-code with a new tool (in-development) which coordinates segmenting and planar/non-planar slicing of sub-volumes, and the conic sliced segment was sliced with 25° conic angle so it remains printable with the vertical nozzle unlike the simulation where a 4- or 5-axis FDM printer is required:
Conic Sliced Overhang Segment
The simulation as reference:
and the actual print process with vertical nozzle on a low-cost 3-axis FDM printer:
Excerpt of the actual printing process with brief annotations:
Tilt Sliced Overhang Segment
Just for sake trying out, instead of conic sliced overhang segment, tilt sliced and 45° Z rotated to nicely extend to the maximum overhang position:
and the actual print of a slightly lower model but with the same features:
Comparing Tilted Sliced vs Conic Sliced Overhang Underside
Overhang In/Out: 2 Overhang Conic Segments
And revisiting the Overhang In/Out Model, which features ingoing and outgoing overhang, segmented into 5 sub-volumes:
ingoing1) overhang: conic (inside-cone mode)
outgoing1) overhang: conic (outside-code mode)
1) when dealing with conic slicing, the direction of overhang matters when deciding the mode of conic slicing, e.g. outside-cone or inside-cone.
and the actual print, a half of the model so the printing of inner overhang on the lower part of the model is visible:
It took me a few days to tune the 3-axis FDM printer to print in acceptable quality of this Overhang Model No 5 and also Overhang In/Out Model. A strong part-cooler was mandatory, well adjusted print temperature and slow perimeter as those extrusions align horizontally without vertical support; and it worked: the main idea is to segment and limit the overhang part to ~2mm thickness – a quasi “balcony” – which still allows a classic vertical nozzle with part-cooler to print such, and then switch back to planar printing again.
Another overhang piece, stretching out into one direction; the lower part Z-planar, and the overhang conic (outside-cone mode) with an offset to align better with the lower segment:
Overhang Out No 5: 3 Segments: 2x Z-planar & Conic
Perhaps a more realistic approach using the conic part as a “balcony” just for the overhang part sufficiently thick to carry next segment and switching back to Z-planar:
Early tests have shown the thickness of the conic overhang “balcony” depends on the actual length of the in-air overhang, where print speed, part-cooling capacity and extrusion consistency determine the geometrical accuracy.
Unlike with ordinary Z-planar slicing, it may be suitable to dedicate a particular slicing method and orientation for sub-volumes in order to take advantage of the possibilities like avoiding support structure, particular strength properties or surface quality.
This of course opens a wide-range of possibilities and complexity therefore:
but I think it’s worth it, in particular when a piece is printed more than once like with small series manufacturing / production.
The examples have been produced with various slicers and combined with a new application coordinating the segmenting and dedicated slicing methods, which currently (2021/04) is in development; it also involves a new file-format describing the segmenting and its slicing settings. The segment positioning was done manually as a start, but I expect with more experience and research some cases can be detected automatically.
Sub-volume segmenting is just one approach to take advantage of 5-axis FDM printing, another is continuous slicing along the form.