Abstract: A power crimping tool especially for use with a fitting of ring shape having a pair of oppositely extending fins on a ring diameter, has a base on which is an extending anvil with a first planar surface having a first die configuration therein. Pivoted on the base is a lever generally overlying the anvil and having a second planar surface having a second die configuration therein. A power driver on the base connects to the lever through a pair of toggle links having pivot pins interconnecting the toggle links themselves, connecting one of the toggle links to the lever and connecting the other toggle link to an adjustable mount for setting the toggle links slightly away from a straight line in one extreme position and so positioning the first and second planar surfaces a predetermined distance apart. There is a spring for return motion of the lever and there are guides for confining the lever laterally. There is also a protected manual control on the base for regulating the power driver.