Still in production, the VersaMil is an interesting accessory designed to be both attached to a lathe, or almost any other machine tool, to increase its versatility - and also as a stand-alone unit which can, for example, be mounted onto a compound slide rest and then attached to very large components and machining operations carried out directly on the workpiece. The use of the attachments is limited only by the operator's imagination and ability to rig up some attachment to the job; little publicised is a whole sub-industry of portable machining expertise that uses not only the VersaMil but a variety of other bolt-on, clamp-on and magnetically-held devices.
Built originally by Dumore Grinders in Wisconsin, the VersaMill was thought to have been introduced during 1952 (though actual details are hazy) and quickly found a home in the US Military for use on both ships and in thousands of maintenance trucks and trailers - indeed, the VersaMil set is still installed in virtually every small ship and submarine in the US Navy. In 1978 Dumore sold their tool line to the Phillips Corporation and the Versamil part of the business acquired by the present owners in 1999. In addition to the original VersaMil the Company now manufacture a much larger version, the Master Milling Machine, a device that can have heads with a massive 50 taper spindle and motors of up to 20 h.p.
Of simple but ingenious design, the VersaMil is composed of a few basic elements: a hardened and ground spindle with a No. 2 Morse taper contained within a head holding an oil-bath-lubricated, right-angle-drive gearbox. A precision feed-screw drives the head up and down four hardened and ground columns arranged in a square pattern and sandwiched between a cast iron base plate and top cap.  The 1725 rpm motor is mounted on a platform at the rear and drives to the gearbox via a single V-belt - the mounting being designed so that should motor get in the way of a job on one side it can be removed and replaced on the other.
Although the unit is perfectly usable on its own, a range of attachments is marketed to extend its versatility including internal, external and deep-hole grinding units, a high-speed milling head, a shaper attachment, a "universal" head, two sizes of feed table to adapt the unit for self-contained operation and a dividing head designed specifically to attach to a lathe and allow the accurate indexing of the spindle when machining gears or drilling holes in a flange.
If any reader has photographs of their Versamil in action, the author would be pleased to hear from you.