Marlin supports arcs in Gcode - Which slicer does as well?
August 15, 2013 01:45PM
From what I understand the Marlin firmware is able to follow arc movements when presented them in gcode. Is sli3r the only slicer that supports arcs?

Edited 1 time(s). Last edit at 08/15/2013 01:48PM by jzatopa.
Re: Marlin supports arcs in Gcode - Which slicer does as well?
August 15, 2013 02:51PM
I know skeinforge does, but at the time I tried it, there was a difference in the implementation. I forget the details, but it was something like the slicer producing absolute coordinates and the firmware expecting relative, or vice versa. I seem to remember that the respective authors felt heir implementation was correct.

Also, skeinforge crashed on me a few times while in that plugin.

End result - I turned it off.
Re: Marlin supports arcs in Gcode - Which slicer does as well?
August 15, 2013 03:01PM
Part of the problem is arc detection. STL files are all triangles - no curves. So the slicing program would have to make assumptions about what should be a curve and what shouldn't. A better file format would solve that problem.


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Re: Marlin supports arcs in Gcode - Which slicer does as well?
August 16, 2013 06:01AM
Marlin doesn't really support arcs. It cuts arcs into a number of straight movements internally, so there's no advantage of using arcs over sending these short straight lines directly. Other than perhaps better bandwidth usage.


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Re: Marlin supports arcs in Gcode - Which slicer does as well?
August 16, 2013 06:04AM
Does any geometry/maths pro here know how his could actually work?

If you define parts of a mesh as splines (be they Bezier, NURBS or whatever) can you slice them to get a description of the resulting curves.

How would one then work out the infill? Currently slicers use polygon offset libraries - could you similarly work out the 'offset' of a curve, or would you have to convert it into a poly first?

Edited 2 time(s). Last edit at 08/16/2013 07:36AM by marcosscriven.
Re: Marlin supports arcs in Gcode - Which slicer does as well?
August 16, 2013 07:51AM
too processor intensive, at least until arm cortex takes lead or a strong enough case is made for expensive 32 bit processors for boards used in general 3d printing. The trend is for lower cost hardware, and minimal support costs. the strengths of using arduino as is.

slic3r will do arcs if enabled, at least older versions can.
the arc is broken down into segments that are manageable by marlin firmware to prevent over calculation. It effectively does process arcs if you consider the arc accurate to placement of 0.1mm the general resolution of filament placement on a reprap printer meaning any more detail will not improve quality of the arc drawn. the arc accuracy can be changed in firmware.

as for skeinforge it supports arcs only in infill or fill script around when it changes direction. general solid layers and perimeters do not.

Edited 2 time(s). Last edit at 08/16/2013 07:55AM by jamesdanielv.
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