Newbie question about homing and coordinates and CAM

["Barry E. King" <beking-at-home.com>]

I apologize in advance if this is a FAQ or something I should otherwise be
able to derive....however...I am a newbie with machining.  This may not even
be the right forum for the following questions, if so please advise.

Since installing the home switches (mechanical snap switches) the system of
course resets itself to 0 on all axis.  I have the home switches set at the
extremes of each axis with the table all the way left and forward whilst
facing the machine, and the spindle all the way at the top.  I prefer to
work with Z 0 being the highest point on the work piece just because I find
it easier to think about things in that fashion when creating the tool path.
Plus, anything with a -ve in the Z is going to be a cut so it seems to make
checking the code a bit easier.

Before the switches just initialized EMC with the piece set up and ready to
go, and set the tool height to the topmost surface of the part.

How to I set the machine coordinates for a piece to be machined?  Or, do I
need to adjust my practices now and generate tool paths with the new home
position in mind?

I had been considering putting +/- limit switches and placing optical home
switches in the center of the machine's envelope, but I am not sure if that
is a good idea or not.  What is typical or standard practice?

Last question, although I have successfully used BobCAD/CAM 17 to create
workable tool paths, I find the program obtuse and buggy and frankly
fallling short of the mark for what is sold as a professional software
package.  BobCAD definitely has some nice features but it is very clunky.
Most stuff so far has been easier to do by hand in IntelliCAD, but I will
need a good CAM package for more complex parts.  Are there affordable or
better yet free CAM solutions for linux?  Even a Win32 version would do the
trick.


Thanks,

Barry