Friday, October 12, 2012

More CNC friendly Board-Off

During the week I replaced the macros for exporting the board outlines as DXF files which hopefully mean that the outline generated in BoardOff can be used by CAD/CAM software without any modification to drive a CNC machine.

It turned out to be easier than I thought. I just created a basic DXF drawing in ACAD9 with the types of lines, curves I wanted to added. This gave be the nasty, in coherent header and a proforma for each of the curve types I needed. A bit of cutting and pasting to turn it into VB and ta daaa

 Previously the outline was made up of 1mm, seperate line segments. When I tried to load it into Mach3 (Shareware CAD/CAM software) it didn't create a tool path correctly. With the upgrade I've changes to a new type of DXF entity called a polyline which is a single line made up of a long list of coordinates - much like G-Code which is the language of CNC control.

 LazyCAM, which is the tool I used for creating the G-Code to import into Mach3,appeared to create a sensible tool path and didn't miss anything. Yet to be tested on a CNC but I'm hopeful that the output from BoardOff can be loaded into a CAM package without modification.

 So far, I've only upgraded the outline template. The plan is to do a bit of work on the rocker jigs and explore whether its possible to generate a 3-D surface for the rocker table. From what I've read you can take a grid of 3D points and create a topological path to pass a smooth surface through them - which sounds like a 3D spline fit. It might be possible with BoardOff to pull out the vertices for 1mm x 1mm tiles (a POLYMESH in DXF speak) and use that. Not sure how smooth the surface would be though. Maybe enough if your willing to clean it up a bit before using it.

  Screen Capture BoardOff output in LazyCAM