Manufactured by the Machine Tool Division of Hamilton Associates Inc. in their own factory at 1716 Whitehead Road, Meadows Industrial Park, Baltimore, Maryland 21207, the miniature Hamilton vertical and horizontal milling machines were sold from the mid-1960s onwards. They were advertised as being suitable for Research and development laboratories, the educational needs of industrial arts and vocational training, manpower training and vocational rehabilitation and as a stand-by tool in industrial machine shops - though oddly they missed out on their appeal to amateur model and experimental engineers. Both were based on the unit attached to the Company's combined lathe and horizontal miller, an arrangement that had been tried as early as the latter part of the 1800s when several of the high-quality American Bench Lathes - Stark and Cataract amongst them - had been offered with a horizontal milling attachment built onto the left-hand end of their beds.
Each machine shared the same knee assembly and single-T-slot 14" (355 mm) long and  2.75" (70 mm) wide table with a longitudinal travel of 8" (203 mm), in traverse of 3" (76 mm), vertically 4.25" (108 mm) and with dovetail locks provided for each axis. Apart from the table and knee, the construction of each model differed according to its special function.
On the vertical type, sixteen speeds were provided in two ranges; the low range being 150, 227, 317, 479, 554, 720, 954 and 1175 r.p.m. and the high 360, 545, 760, 1150, 1330, 1730, 2290 and 2820 r.p.m. Not provided as standard, but available as an option, drive came from a rear-mounted, 1-phase, 1/3 h.p. 110-volts motor controlled by a safety no-Volt release push-button starter.
Arranged like a drill press, the motor was mounted on a plate at the rear of the head and drove (on early models) direct to the spindle using a Gates belt running over 8-step pulleys; the use of the narrow but very strong 5 mm wide Gates belt on this tiny miller enabled far more speeds to be provided than possible with an ordinary Z-section (10 mm wide) wedge belt. As the head and motor were carried on a round overarm, the entire assembly could be moved in and out and also swivelled 90° each side from upright, a degree scale being provided to check the setting required. It appears that late-model machines may have had a modified drive system that included a tensioning jockey pulley and two side-by-side belts in order to transmit more power; the change might have coincided with the change of the maker's badge from a black oval to a white or silver rectangle
Bored through 3/8" (9.5 mm) and provided with a suitable drawbar to retain collets and cutters, the No.1 Morse taper spindle ran in precision taper roller bearings and was fitted with a threaded nose - this though to be 1.5" x 10 t.p.i.. Up and down travel of the spindle was 2.75" (69.9 mm) controlled by a handle connected to a rack machined into the back of the 2-inch diameter quill. Unfortunately, no fine-feed handwheel was provided, but the handle could be repositioned for ease of use by a pin that engaged with a series of holes drilled into the mounting boss - and screw-adjustable stops were provided on the vertical ruler.
The clearance between the spindle nose and table was varied from a minimum of 1.75" to 6" (44.45 to 152.4 mm) and the centre line of the spindle to column V-way from 1.5" to 5.5" (38.1 to 139.7 mm).
Accessories available included the previously-mentioned electric motor and push-button starter, a safety cutoff for the cast-iron belt guard, milling vice with T-bolts, cutter-holding stub arbor, shell-mill holder, end mill adaptor, drill chuck, a set of split collets and a workbench suitable to hold two machines.
Very much smaller in real life than it appears in photographs, the vertical model stood just 26" (660 mm) high, 17" (432 mm) wide, 24" (610 mm) deep and weighed, with motor and switch, 120 lbs. (53.43 kg).
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On the horizontal model eight speeds were provided of  360, 545, 760, 1150, 1330, 1730, and 2820 r.p.m. - though on this version the makers did offer other ranges to special order. Not provided as standard, but available as an option, drive was from a side-mounted, 1-phase, 1/3 h.p. 110-volts motor controlled by a safety no-Volt release push-button starter. From the motor, the drive passed, using a single belt, to an intermediate 8-step pulley and then to the horizontal spindle with both being of the narrow, 5 mm wide Gates type, their use enabling far more speeds to be provided than possible with an ordinary Z-section (10 mm wide) wedge belt.
Fitted with a screw thread (possibly 1.5" x 10 t.p.i.) and a No.1 Morse taper socket, the spindle drove a 1/2" diameter arbor supported by a drop-bracket on the end of a round overarm.
As on the vertical model, the single-T-slot table was 14" (355 mm) long, 2.75" (70 mm) wide, had a longitudinal travel of 8" (203 mm), in traverse of 3" (76 mm), vertically 4.25" (108 mm) and with dovetail locks provided for each axis. A separate unit, the main column was bolted to a substantial, deep-base casting and, in turn, the whole surrounded by a standard-fit, 13-inch square sheet-metal chip tray.
Like the vertical model, the horizontal was much smaller in real life than it appears in photographs and stood just 21.5" (546 mm) high, 19" (483 mm) wide, 17" (431 mm) deep and weighed, with motor and switch, 90 lbs. (40.8 kg).
Accessories available included the previously-mentioned electric motor and push-button starter, a milling arbor (why was this not part of the standard equipment?) a safety cutoff for the cast-iron belt guard, a milling vice with T-bolts, a cutter-holding stub arbor, shell-mill holder, end-mill adapter, drawbar for the horizontal arbor and a workbench able to carry two machines.. 
Very much smaller in real life than it appears in photographs, the vertical model stood just 26" (660 mm) high, 17" (432 mm) wide, 24" (610 mm) deep and weighed, with motor and switch, 120 lbs. (53.43 kg).