Re: [CAD_CAM_EDM_DRO]floating z axis

I am a frequent operator of a professionally built LPKF PCB milling
machine. Scotch tape is quite sufficient to hold the PWB down while
milling. The LPKF system also uses two pins to align the PWB. The
cutter is surrounded by an annular ring (a "donut") that provides a
stop. The ring can be adjusted up or down to control the cutter
depth. The z-axis is driven to the stop (contacting the PWB) by a
solenoid on the cheaper models and pnuematics on the high end
models. You can see examples at: http://www.lpkfusa.com/ (<---
perhaps someone can tell me how to make this a link)

The system works quite well. In the hands of a skilled user a
tapered cutter can produce PWB traces reliably to +/- .5mil

You would think that the annular 'foot' rubbing on the board would
cause probems, but if it is smooth it works very well.

Hope this helps