A tool to determine the correct distance apart and depth of engagement of wheel teeth and pinions. It has a pair of parallel runners between the centres of which two wheels, or wheel and pinion, or escape wheel and pallets, may be adjusted to work properly together. The distance apart of the runners is transferred, as with dividers, to the plate where the arbours of the wheels are to be planted. Some old catalogues show a triple depthing tool which has an additional pair of runners in a frame at 90?to the other runners, for adjusting the interaction of a contrate wheel, escape wheel and pallets for a verge escapement.