Quote Originally Posted by magicniner View Post
Work Offsets allow you to have bed level as Machine Z-zero with the top of work as your Work Z-zero, that's what Work Offsets are for. ;-)

The professional CNC machinists I've spoken to tend to use a top of part/stock Z zero,

- Nick
Unfortunately DIY cnc machine will be always one step behind due to the lack of absolute encoders or scales that at all time tell the machine the exact position, even if power switched off. To rely on working offsets on a machine equipped with cheap chinese limit switches is ridiculous. As i said somewhere above on a couple of occasions i measured 0.4mm initial imprecision and now while browsing 3D printer stuff i found some reports that temperature also changes the situation..

Now the thing is that you are right in a way, cause on a DIY machine, nothing happens if 0.1-0.4mm things are not right when homed. But you could not continue aluminum job if power is cut or you need to reset steppers, i have tried that to no avail, at least a couple of times