[Jim27]

I am looking at a 2 sided FR4 board for RF (VHF) where one side is used for ground plane - the layout already exists(scanned artwork from an old magazine). The ground plane has about 30 holes that are from about 0.2 - 0.7 inches across and are odd shapes. I am just getting started with PCB milling and wondering how I can produce the large openings. I suppose I could mill the outlines (using an normal isolation V bit) and then manually peel off the unwanted copper foil. I could pull the drawing into a CAD program and generate gcode for milling them as pockets but wonder about the life of the end mill with all the surface area. Any other suggestions?

[blinkenlight]

Although one can always use generic tools and plugins, PCB milling is typically done starting from a set of Gerber files exported from whatever CAD you designed your board in, using one of a number of specialized applications explicitly meant for PCB millings tasks. There are a number of these, and more or less all of them are capable of generating "rub-out" toolpaths for inter-track copper removal, in addition to the typical "isolation" toolpaths that only trace around the tracks. The most up-to-date and easy to use is probably FlatCam (FlatCAM: PCB Prototyping CAD/CAM), which can generate g-code for all work-phases - isolation / rub-out / drilling / outline cutout. For "rub-out" you simply select your copper Gerber and generate a "non-copper region", then select the resulting layer and generate a "paint area". It's all subject to various settings like margins, tool width etc of course - one generally does rub-out NOT with the V-tip engraving stylus used for the isolation pass (that would take basically forever), but with a standard cylindrical milling bit: 1mm/2mm/3mm, depending on how precise you want to be and how patient you are). What results is a toolpath like this, from which FlatCam can just export G-code to mill it directly:

Attachment 364316