on a fixture using the mounting holes 48 b provided in the cylinder mounting plate 48 referring again to fig1 the mode of movement of the invention will be described the motor housing 45 is free to move axially along the rail bearings 12 forward movement is limited by the stop block 51 which comprises an adjustable stop pin 28 the adjustable stop pin 28 will generally be an elongated threaded bolt with a locking nut 30 to keep it from moving during forward movement of the motor housing 45 compressed air is applied to the cylinder 16 moving the threaded shaft 17 outward the threaded shaft 17 being secured to the motor housing 45 will move the motor housing 45 forward within the constraints of the rail bearings 12 the motor housing 45 will move forward at a rate determined by cylinder 16 until it is about to engage a work piece at a distance set by the operator the velocity controller 14 will engage the adjustable stop pin 28 forward velocity of the motor housing 45 will there after be limited by the velocity controller 14 the velocity controller 14 is a type of shock absorber device well known in the art having an external pin 14 a and an internal plunger when the external pin 14 a impinges upon the adjustable stop pin 28 an air volume inside the velocity controller 14 is compressed and allowed to bleed out in a controlled fashion which regulates the forward movement of the motor housing 45 the motor housing.