I will suggest this method of keeping track of your origin.
I am now in the middle of a 3 day carve. ( not 3 days long but i am splitting up a 4 hour program over 3 days since I only get an hour or so a night to work on it. )
I do not leave the controller on. It is shut off. And I do not worry about keeping the axis in the position I left off at.
Start by clamping a block on your table that can be permanent, for the duration of your job, and away from your work. I have a notch cut out of the front left corner of the wasteboard that is for this purpose.
Use your tool setter block to find the front left corner of that block. Make that the origin for now.
Write down the numbers circled in the pic below:
Then find your origin on your actual workpiece and make that your origin in the usual way.
Write down those numbers as circled in the pic below:
Now use paper and pencil or Notepad as I did to organize those numbers and subtract the first set from the second set as done below:
“ORIGIN OF WORK:” is the origin of the actual workpiece I am working on.
“FAR FRONT LEFT CORNER:” is the origin of the cutout on my waste board. This would be the permanent block you clamp somewhere. This number will be different every time I start the machine and home it. Only by .010 to .020 but enough that it would ruin my work. This is why I do not just use the offsets from the home position.
Then start your job in the usual way and stop it when you want and shut every thing down. Move the axis if you want - it doesn’t matter.
Then when I come back to start the job again be it a day or a week later - I start my machine and home it.
Then I find the front left corner of that permanent block I still have clamped to the table and make that the origin temporarily.
Don’t write down any numbers now - it is not needed.
Go the the MDI and type in the X and Y distance to move I calculated before:
I leave the the Z out of it for now because rapiding on X Y and Z at the same time is dangerous if anything is in the way. Leave the spindle up high. ← I stress again PUT YOUR SPINDLE UP HIGH BEFORE YOU PRESS PLAY! ( Don’t ask me how I know this is so important)
Press play on the MDI and go to the new offset position. Make that new place the X and Y origin.
Then move the spindle to a safe place and press the Z0 button on the controller to take it down to the Z0 of that permanent block.
Then type in the MDI again G0 G90 Z.651 ← this is the number I computed earlier.
Set that new place as the new Z0.
That’s it. ( it takes longer to explain it than to do it )
You are now back to your original origin.
If you take the time to setup this separate block and record these numbers before you start a big or expensive job you will not have to worry about finding your origin after a power failure either.
You will also note I wrote down “Roughed to .980 above Z0”
That is so I can stop a 4 hour program, go into it latter and edit it to start right where I left off. That is a discussion for another day.