This page describes a CAD program that I am developing to use with my CNC router. The program is intended to allow me to draw things and export my work as a DXF file. Here is a link to a reference document for DXF. Here is a forum page where I discuss Processing code that is used to create DXF code containing lines, circles, arcs and ellipses. There are many free CAD programs out there and I am not recommending that you use this one. This is mostly indulging my hobby of writing code.
To add lines: First add points using the Add_Pt button then select point and press the "+PT" button, to remove points from line list, select point and press "-PT" button. A series of connected lines can be created by adding additional points to the line point list. When all of the points have been added, press ADD button to add lines to the drawing.
To remove a line, select two points at the ends of the line and press the "CUT" button
This came in handy when I made my rocking chair. I had purchased a set of templates for the chair and wanted to cut out the parts using the CNC router. I cut out each paper template and glued them to mdf boards. Using the straight edges of the mdf and a T square, I marked the template every 20 mm in the y dimension. I then measured x values for each y position and entered the x and y values into a spreadsheet. To create a file that the DrawDXF program would read, I added two lines to the top of the file and two lines at the bottom. The two at the top indicate that the file is scaled in mm and contains a set of points. These lines are:
true scale
points
The lines at the bottom of the file indicate that the points are connected sequentially by lines:
lines
all