Abstract: The milling machine tool holder or chuck is used to support a spindle on a chuck axis through which a crossbar is transversely and slideably mounted. First and second ends of the crossbar adjustably support a mirror and a dial indicator, respectively, so a machine operator can see a dial face of the dial indicator that is not visible and facing away from the operator. The crossbar has a bend which enables the dial indicator to be articulated to conveniently measure features near the chuck axis without interference between the spindle and the dial indicator. The dial indicator is securely mounted to a clamp adapter which is mounted to the second end. A wedge-shaped slot in the adapter is configured to receive and secure one of a plurality of sizes of dial indicators.