I am quite new to mechanical engineering, but currently working on a project which I eventually want to sent to a CNC service for machining. Many services I found can manufacture to, e.g., ISO 2768-m tolerances, (+/- 0.1mm from 3mm to 6mm, +/- 0.2mm from 6mm to 30mm nominal sizes).
This range of tolerances are sufficient for most of my part, but for some bore diameters, locating features, and their relative position I require a tighter tolerance, which I should specify in a drawing (wherever those requirements are tighter than ISO 2768-m).
However, I really struggle to understand how to interpret the general tolerances (e.g., from ISO 2768). I attached a sketch of a simplified geometry I want to tolerance properly. On the left there is the ideal CAD model (no tolerances) and on the right is how I understand that ISO-2768-m general tolerances would apply to my part, i.e., whenever the produced parts is within the boundary on the right side, the manufactured part would be considered okay. I assume I might be very wrong about this interpretation and would highly appreciate if somebody could help to clarify if/where I am wrong. Thanks a lot!