Re: milling circuit boards

> Is it really and truly cheaper to make these
> boards after you factor in your time and amortize your equipment?
>

I make boards and prototypes using everything from hand wired
protoboards to professional board houses, and I think if you already
have a CNC machine in place, as I do, there are times when milling a
PCB board makes sense. If I have a project where the build quantity
will be low, professional appearance or packaging is important
(ruling out a handwired proto) the board is on the simple side and
I'm in a hurry and expecting multiple revisions, then milling the
boards is the way to go. Getting set up to do the first one was a
hassle, but now that I have the process in place its pretty quick
and painless. I don't like messing with chemicals and if you etch
the board you have to set up the CNC machine to drill the board
anyway, which is about the same effort as setting up to both drill
and mill it, so I prefer milling a board over etching it.

I use Eagle for the board design, and Eagle will output the design
in the HP plotting format. I then read that and the Excellon drill
file into the SheetCAM program (www.sheetcam.com) to generate the G
code to drill and mill the board.

I don't know if I could justify setting up a CNC mill or router from
scratch to do this just for PCB prototypes, but if you have a CNC
mill in place already its definitely worth setting it up to mill and
drill your boards.

Paul T.