I'm a newcomer to CNC. I've converted a standard bench mill with all the recommended bits and pieces - limit switches wired in series for each of x,y and z with the lower z limit adjustable to cutter length so there's no chance of it meeting the table. In the absence of any 'bench mark' CNC knowledge the mill is currently set up as per the Mach3 manual with relatively slow feed rates and I've run a couple of the included wizards in aluminium to test everything - especially me!!!

So far, so good... My questions relate to the use of home settings. I've read the manual and posts, here and elsewhere but I'm having trouble understanding the real value of home switches and where the home reference 0,0,0 points apply in the software. After years of setting up conventional mills with the 3 DROs zeroed at a designated datum point, I've approached CNC on the same basis. I've tweeked the G Code to establish where the 0,0,0 datum is, jogged the mill to the work piece, zeroed XY and Z, moved all three axes away and engaged warp drive... The Estop is on a flying lead and the limit switches protect the machine and so far its done what was expected.

However I'm on a steep learning curve and easily confused with this new terminology. I'd appreciate some logical (and uncomplicated) explanation as to where I'm missing the point with home switches/settings - what are they used for? I know the size of the table and how large my working area is. Logically the only time limit switches become vital is when human error overrides software. Having said that it would be relatively straight forward to redesignate the limit switches as home switches as presumably they would fulfill the same function of not overunning the machine but I need some clarification of the shortcomings of this plan.