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PCB Routing

I recently acquired a Roland iModela iM-01 which I intend to use for routing small PCBs. This is the first of a series of articles about getting to a working toolchain. There is a bit of a learning curve with using CNC and many of the tools only exist for Windows. One of the things I wanted was a tool path tracer - so I could quickly see what the NC-code / RS-274D / G-Code does.
After much searching I came across tkBacktracer (http://sourceforge.net/projects/tkbacktracer/) a large tcl program which seems to work well and is extremely portable. It does particularly well with the output of PCB-GCode a plugin for Cadsoft Eagle.

The problem I had with the code I generated was that it was defined in the negative X-axis (Machines generally don’t have a platter that moves further than their physical origin) as a result the code appears to fail with the physical origin - this should not actually be a real problem on the physical machine as the user origin just needs to be shifted such that the model fits inside the working area of the machine, it does however add complexity in that an “unusual” origin needs to be selected and causes problems for other simulators.