Quote Originally Posted by Boyan Silyavski View Post
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.
That statement is true but is not relevant.

Having your bed as machine Z zero and using a work offset is no more complex than having your bed as work zero and setting the bottom of your stock as your Z zero in CAM, it doesn't require any fancy encoders or switches, it does require a little planning, but no more so than using a bottom of stock zero in CAM.

Having your bed as machine Z zero and using a work offset does have the considerable advantage that if machining or engraving a series of features in a surface you can do this on a variety of thicknesses of stock without having to refer to CAM to see what stock thickness you had set and then calculating a compensating offset ;-)

- Nick