Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

[JOGARA]

So I attempted to make my own soft jaws. The CAD was not easy but managed in the end.
Wanted them so I could put my stock aluminum in and machine it all the way to finished product. This only required 2-3 setups.

Decided on machine half the stock off and that left me with 2 cases for my electronics, I can then shove that on the soft jaws to mill out.
Using a 6mm hole to get X and Y and eye balling Z (Z being really easy to do).
Either something is out in my measurements or the 6mm hole method just isn't accurate enough.
Obviously on this machine it is not that accurate but to be nearly 0.3-0.5mm out in X and Y it must be my error.
I am also just using a standard vise, might not help though it has been pretty solid so far. I can only guess my main issue here is going to be repeatability.

Really need a 3D probe I think to help here.


What I am going to do is go back to my old method of super gluing my stock on a bit of 5mm which then allows me to mill out everything.
I really want to be able to step this up to a production level though as I have quite a few to make, just being able to run step one 20 times and then step two 20 times would be great. No changing tools every 10-30 mins. Just swap out the part for the next operation.
That and the glue is a pain to clean up and sometimes does not stick fully resulting in the part flying.