You should make the tool holders from a sacrificial material (nylon, plastic, etc.), if your machine has a crash, the tool holders will break and not damage the spindle bearings or the carousel. Also mount a physical home switch so you can index it or use an absolute rotary scale. This will save you time when homing the machine. Do you have an air source to blow out your spindle? If there is a chip on the tool and is not blown out, it will affect accuracy. Alignment pins on your tool holder instead of a lot of bolts will also help when there is a crash, the pins will align new tool holders and the bolts just hold them into place, if you don't want to use pins, machine a guide block or use a key for alignment. Tim