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Category Archives: CAM

Towards medial-axis pocketing

Update: some work on connecting MICs together with bi-tangent line-segments, as well as a sequence of lead-out, rapid, lead-in, between successive MIC-slices: It gets quite confusing with all cutting and non-cutting moves drawn in one image. The path starts with an Archimedean spiral (pink) that clears the initial largest MIC. We then proceed to "scoop" […]

Rendering an image with VTK

For exploring and visualizing various pocketing or area-clearing milling toolpath strategies I am thinking about reviving the "pixel-mowing" idea from 2007. This would be simply a bitmap with different color for stock remaining and already cleared area. It would be nice to log and/or plot the material removal rate (MRR), or the cutter engagement angle. […]

With FreeSerifBoldItalic, don't ever write "zj"!

Update: Here is "VX" with FreeSerifItalic. There is overlap in LibreOffice also. For the most part truetypetracer produces valid and nice input data for testing openvoronoi. But sometimes I see wiggles, and now this: It is frustrating to try to track down bugs in downstream algorithms that take this as input, and assume all line-segments […]

V-carving test

A first try at v-carving, with toolpaths produced by the ttt2medial python script.

Non-smooth output from ttt

I tried cranking up (10-fold) the number of line-segments that are used when approximating conics and cubics with lines. The results are mostly OK, but sometimes "wiggles" or "S-curves" appear, which cause problems for the medial-axis filter. This "P" is an example: The medial axis on the right does not look correct. If we zoom […]

EMC2 Filters

I hacked together a few python-scripts that can be run as "filters" in EMC2. They are opened/run from AXIS and produce G-code into EMC2. The first one is ttt2ngc which simply demonstrates my C++ port of Chris Radek's truetype-tracer. The original code is a rather monolithic C-program while my C++ port is divided into smaller […]

Graph filters

I've put together two graph filters that can be applied to the VD. The first one detects the interior or exterior of a polygon. When the VD is constructed the polygon boundary must be input in CW order, and any islands inside the polygon in CCW order (or vice versa). This allows running other downstream […]

2D Offsets

Once we have a VD it is almost trivial to calculate 2D offsets. While the VD for n line-segments takes O(n*log(n)) time to calculate, the offset-generation is a simple "march" that takes O(n) time. In this "A" example it takes 24 milliseconds to calculate the VD and less than 1 millisecond to produce all the […]

VD Alphabet

There was an issue with handling collinear line-segments, which is hopefully now fixed. OpenVoronoi seems to deal OK with most characters from ttt now. I am still getting some Warnings about numerical instability from LLLSolver, possibly related to these high-degree vertices which don't look quite right (this is a zoom-in inside the circular dot of […]

TTT++ and font-vd

Update: Now all the capital letters work! I wanted to test my VD algorithm on font-outlines. So I ported Chris Radek's truetype-tracer to c++ and added some python bindings. Here: https://github.com/aewallin/truetype-tracer Because my VD code cannot handle circular arcs yet, I took some old code from TTT 3.0 and made converting conics and cubics, the […]