The following drawing and detailed explanation of the operation of Vincent Dunker's contact printer were graciously provided by his grandson, Leo Pruneau, of Woodend, Queensland, Australia.  Leo Pruneau has previously held many high-level positions in automobile manufacturing including director of design for GM's Australian subsidiary, General Motors-Holden's Ltd.  As design director, Leo was responsible for many of the beautifully styled Holden automobiles which are now admired by automobile enthusiasts around the world. (see Vincent Dunker's biography at http://dchis.com/Dunker%20Biography.htm,  or click on the blue lettering below Vincent's photo on the 1950s page.

 
 
 
1.  Sliding bar at the right (with handle in place) before handle is moved downward   2.  Sliding bar moved left by downward motion of handle advances print paper

The apparatus described above is the contact printer’s primary feed and control mechanism, and is an important part in the functioning of the printer.  It works in the following manner –
 
 From the roll, the contact printing paper is fed between the aluminum plate and the blue metal plate, and under the front and rear slotted components (DOGs) to the side, located on the top of the printer box.

 When the handle is operated, activating the rod-mounted wood strip, to move it forward and backwards the DOGs work in combination with each other.  The rear DOG, attached to the wood strip, pushes the contact paper forward, while the front DOG, mounted to the printer box, holds the contact printer paper in place.


 Depending on the direction of movement, in the forward motion, the rear DOG's ‘rubber-tip’ wedges against and grips the contact paper to push it forward.  On its backward movement, the rubber tip – because of the angle and the bevelled end shape – slides over the contact paper without gripping it.
 
 Conversely, the front DOG functions in the opposite manner.  Due to the angle of the rubber tip, and its bevelled end shape, the contact paper slides forward without being gripped.  However, it cannot move backwards because the contact paper becomes wedged against, and gripped by, DOG's ‘rubber tip’, and held stationary.

 The printing of the negative occurs at the end of the stroke, when the handle is in the flat position, and the two DOGs are closest to each other.  To continue after the negative has been printed, the wood strip along with the attached DOG is moved backward by the handle until it stops at the end of the stroke against the upturned blue metal part.  At this stage, the rear DOG, with its rubber tip, is in position to grip and push the contact paper forward to the next frame for the printing cycle to continue.

Due to its rapid recycling action, the printer was capable of producing up to a dozen plus images per minute from a single negative!