CNC PCB Milling

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I use for the Lite version of CadSoftsEagle to capture schematics and pcb designs. Eagle is an extremely powerful tool, with a free version avaiable for non commercial users. One feature of Eagle is a nifty programming language to create user language programs, simply called ULP's. There are several ULP's available to mill pcb's that can be downloaded from the CadSoft ULP downloads page. Cadsoft Downloads But the one I have settled on using is Pcb-gcode PCB G-Code Yahoo Group a ULP (user language program) associated with CADSOFT's Eagle Schematic Capture and PCB Design Tool. One of the features I like about PcbGcode is the setup window that is available in version 3.3.2. It allows you to specify gcode formats, machine and cutter characteristics.

Once you have captured a pcb design in eagle, simply running the pcb-gcode-setup.ulp from the file->run menu will bring up the setup window. In that window you will see five tabs where you can select the available options.

The beginning of milling boards was rather frustrating for me. Tweaking out backlash, trying various cutters, how to hold boards and hold them flat, cutting rates being the main frustrations. So here are some tips from what I've settled in on. 1. You machine needs to have low values of backlash. 7mills originally on my Y axis was almost impossible to do anything but a very simple pcb. 2. Mill a flat fixture to hold you pcb's. The fixture needs to have repeatable hardpoints so it can be removed and replaced repeatibly. 3. I use double sided carpet tape that I got from HomeDepot. It's very thin, maybe 12mils thick. It adheres to clean hard surfaces very well. (I clean the surfaces with denatured alcohol) So well that in fact I have broken boards removing them because of a little impatience. 4. I feed at 10ipm at 30,000 rpm with a bit I really like: Think & Tinker mechanical etching bits. Specifically the 60degree coated EM2E8-0625-60VC-001. By far this bit is the best I have tried, and can cut isolation paths in the 7mil region. 5. Ebay is a excellent source of low cost blank pcb material. My screen pictoral

More PCB milling links:

MILLPCBS.COM

Chris's PCB milling

10Bull's excellent article on PCB milling.

Yahoo Group on CNC milling of PCB's.

Here is an excellent website for making a PCB holding fixtures clamps and other pertinent info for PCB milling.

Engraver bringing information related to making PCB's.

Depth stop used for precision engraving depth control. The also have carbide engraving bits.

Think n Tinker mechanical etching bits. (45, 60 and 90 degrees)Part numbers EM2E8-0625-45V-001 , EM2E8-0625-60V-001 , EM2E8-0625-90V-001

DrewTronics Andrew Abken's engraving bits.

CAMBAM Brusselsprout (Andy) CAM program.

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