Q. Is it possible to generate tool paths for CNC equipment from IntelliCAD drawings?

A. Use an AutoLISP routine

Small engineering firms often have substantial investment in milling machines, lathes, machining centres and other automated equipment. Many of these devices can be programmed to reliably machine complex parts.

The more sophisticated machining centres often have associated 3D CAD programs, used to generate cutter paths for the creation of parts. After the cutter path for the part has been created using this software, this path is turned into a machine accessible format, such as G codes, for the actual machining process. Unfortunately, different manufacturers tend to favour their own CAD program, and since it is not uncommon for machine shops to own a heterogeneous collection of devices, operators may have to learn several CAD programs in order to fully support the machinery. This can be inefficient.

Experience has shown that for relatively simple machining jobs, it is better to teach operators to use a relatively simple industry-standard CAD program such as AutoCAD or IntelliCAD to create the part drawing and then extract the tool path from that drawing utilising several simple macro programs.

We have found that if a 2D drawing of the part is constructed in AutoCAD and a polyline representing the cutter tool path is created as a separate entity, then it is possible to extract the coordinates of that polyline to a file using a simple AutoLISP function.

We can then produce a printout of the required part, along with a list of the key coordinates for the required tool path. The machine operator can then use his experience to apply suitable lead-in and lead-out paths, plus define the cutter feed rate  and other machine-specific characteristics, and input the coordinate data from the printed list. This system obviates the necessity for learning different drawing programs for each piece of equipment. Moreover, if changes are required to previously machined parts, then it is simple matter to make the alteration to the drawing and re-extract the tool path data.