then when you set your fixture plate as your Z zero using a calibrated tool
and store that position.
Any z positive values (ie: 0.430") you machine at will be exactly as you enter on the control.
ALL tools will see the set Z zero as just that.
setting each part as a seperate Z zero seems a little unnecessary..
and leave a possibility of errors and mistakes.
You need to get into the habit of zeroing every tool you use to the same known datum and this will help you
with everything else.