Posts made by kwisatzsawyer

That's more than fair. I was trying to decide if I wanted to write the slicing part myself so I could get G2&G3 movements from a CAD format. I knew I didn't have the free time for STLs (and apparently neither does anyone else). But I figured if I had a file format that had geometry I could slice it into gcode with Perl. I hadn't thought the problem through past cylinders and spheres before I realized it'd be pointless if the firmwares my printers run don't support true arc movement. Higher polygon count is the solution that makes the most sense if arcs are turned into line segments anyway. I'll put on my TODO list writing a gcode file that builds a simple cylinder (say 25mm radius, 10mm high) and compare that to the same printed from a cylinder of similar dimensions in CAD, exported to STL, and printed. I think you'll be proven right, but what the hell.

Do you think true arc motion planning (instead of a bunch of line segments) would be analogous to 16 vs 32 vs … 256 micro-stepping? My gut tells me it'd be similar: progressively quieter due to smoother operations but insignificant gains in accuracy? Wouldn't smoother tool moves make for fewer / diminished acceleration-caused print artifacts?

tl;dr: the "DefaultArcSegmentLength" in Configuration.h is set to 0.2 (I assume this is mm). Is that a function of the nozzle diameter (0.4mm / 2 = 0.2mm)? For using smaller nozzles, would I then set this to be a fraction of that for smother arcs in G2/G3 commands? How feasible is it to code true arc movements in the firmware?

Longer version: I spent three days printing a Saturn V model and was a little disappointed by the surface finish (using a Ultibots D300VS-PLUS, so circles should be easier). I've read up on the inherent issues with slicing STLs (even high-res ones). And I was toying with writing a processor for OpenSCAD or comparable to get better prints from geometric shapes. But reading the firmware code, it just seems to slice the arcs into a bunch of 0.2mm segments anyway.

Long term, I can see plenty of use-cases for G2/G3 commands (once curved triangle supports / slicing from CAD files directly / etc is a thing). In the interim, I'm wondering about whether it makes sense to just write my own gcode from scratch for some of my projects (e.g. small, high detail stamps for wax sealing). I have 0.15, 0.25, and 0.3mm nozzles. Would it make sense to change the DefaultArcSegmentLength to a smaller increment for the smaller nozzles?

Thanks!