Hello,

My homebuild CNC (in french) http://www.equinoxefr.org/post/2008/10/06/fraiseuse-cnc-do-it-yourself/

and a new version is coming soon http://www.equinoxefr.org/post/2009/11/22/fraiseuse-cnc-diy-v3-episode-1/

With a typical homebrew CNC build, is it possible to mill a PCB with traces small enough for surface mount components? If so — are the homebrew mills we’ve seen on HackADay sufficient, or are more precise motors required?

I’m also unsure as to whether or not the bits thin enough to do the job would snap while skimming across the copper.

If this is feasible, I’d certainly love to build a machine rather than continue to buy etchant…

A CNC PCB board engraver might be one of the easiest types of CNC machines to build. Small work envelope, engraver and maybe three drill bits are all the cutters you need … disco!

There are “spring tension” engraver bits that will just follow the board even if it’s not totally flat. That’s a good way to solve a tricky problem:
http://bbs.homeshopmachinist.net/showthread.php?t=30156&highlight=engraver

As for precise motors, you will likely use a cog-belt pulley to connect the motor to the motion screw, so simply use small on the motor and large on the screw to increase “resolution”. More disco!

I’m building a CNC milling machine, but on reflection I think I should have built a PCB engraver first to achieve some quick success for inspiration (and have a useful tool too).