Every time your machine is powered on you have to "Home - Zero Return " it.
When you start with a new product you have to find, with a 3D-Taster or dial gage, the workpiece-points that you want as G54-XYZ.
When your display shows, X15, Y-10. Z-20. for example you put this in the G54 OFFSET (WORK).
You don't have to "Home" X and Y-axis, maybe only the Z-axis, now you can start-up from this point.
For your own safety it is better to put a Z2. (inch) in EXT so your complete nc-program runs 2 inches above your product so you can
see that everyting goes correct. When you power off your machine and start it up again you must "Home" to zero again but after this
you can start immediately. Till you start with a new product your G54 will be the same.
The G55-G59 you can use when you put more product on your machine table.
When your machine has to start with Z in "Home" position you can change the start of your program like below.
O100( TEST )
G54 G17 G40 G80 G94
G00G91G28Z0
M6 T1 ( or T1 M6 )
S1250 M3
G00 G90 G43 X0 Y0 Z20 H1
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Heavy_Metal
The Netherlands.