The best way to avoid this is to avoid slotting and add geometry so as to provide a roughing clearance, and cut as a pocket down to at least tab depth — then the finishing pass can plunge along the finished edge and not deflect.
The best way to avoid this is to avoid slotting and add geometry so as to provide a roughing clearance, and cut as a pocket down to at least tab depth — then the finishing pass can plunge along the finished edge and not deflect.