Getting volumes of circular milling path step by step

[blusser]

Hi,

what I basically want to do, is to remove something step by step in a circular manner.
For this, I place a small cylinder in a bigger cylinder and make it move in a circular manner.
From this Path, I would like to get the Volume that has disappeared, every n-th. step.

What I have done so far:
I import the miller and the Object in to FreeCAD, so I don't have to create it all the time.
I split the Problem in to the downwards path and in to the circular path.
I placed my smaller object into the bigger Object and move it downwards. This works perfectly and I can get my removed Volumes by using the common command.
My problem:
If I start moving my smaller Cylinder in the bigger Cylinder in the circular manner, my common part starts moving with the smaller cylinder.

So the stuff I milled away moves. I attached the script as well as the objects.

I looked at the Path-Toolbox, but I did not see, how I could get the volumes for each step.
https://wiki.freecadweb.org/Path_scripting

Cheers Blusser