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The unusual and versatile Armor horizontal and vertical "Turret" milling machine was made by the Aircraft Machinery Corporation in Burbank, California; literature indicates that this was a machine designed in the 1930s, and produced until at least the end of the Second World War, in 1945. Three models were offered: the 4H, 5H and 6H; the two smaller differing only slightly in capacity, specification and weight; the baby of the range, the 4H, was fitted with 7" x 27" table (16" of travel), the 5H a 7" x 28" (16" of travel)and the 6H a 8.5" x 32" (20" of travel). The cross feed on even the smallest machine was a useful 7", increasing to 7.5" on the mid-sized model and 8.5" on the largest.
Unlike a conventional miller (but similar in design to a jig borer) the compound table did not elevate; instead, the entire head assembly - which carried a horizontal milling set up at one end and a vertical at the other - could be wound up and down a vertical slideway over a distance of 11 inches. The slideway was mounted on a degree-graduated swivelling base, secured by six bolts to a substantial cast-iron housing, so that each head could be swung into position with the minimum of delay. Because each head had its own motor, and was ready for immediate use, it was often possible to leave work in place on the table and rotate the heads as they were needed; this not only minimised or eliminated the task of resetting, but also saved the time it took to tranfer and remount the job on another machine.
The same vertical head was common to all three machines and was available as the Model A without a quill feed, or the Model B with 3.5" of quill travel by a quick-action rack-and-pinion feed; it was driven by a V belt from a 3-phase 1/2 hp ball-bearing motor bracketed to its side; 6 speeds were provided, from 375 to 5200 rpm, or, with the optional backgear, 8 speeds from 125 to 5200 rpm. The spindle was hardened and ground, ran in Timken taper-roller bearings and was provided with a No. 7 Brown 7 Sharpe taper; the vertical head was not an Armor design, but built under various licences from the Ingersoll, Kearney & Trecker and the Cincinnati Milling Machine companies.
The horizontal arbor, driven from a ball-bearing motor with a final drive by either a countershaft and twin V belts (Model 4H, 1 hp), a Whitney Silent Chain (Model 5H, 1.5 hp) or a "backgear" assembly (Model 6H, 3 hp), was hardened and ground, ran in Timken taper-roller bearings and was fitted as standard with a Brown and Sharpe No. 9 taper - or, optionally, a "National". Although all models had 6 horizontal speeds, their range differed as follows: 4H: 100 to 2000 rpm; 5H 60 to 1200 rpm; 6H45 to 1450 rpm.
The table's longitudinal travel was operated by both a hydraulic drive - with fine, rapid and reverse feeds - and a hand-operated screw thread; when using the hydraulic drive the finest feed rate was 1/8" per minute on all models, whilst the fastest varied between 150" and 180" per minute; the change from hydraulic to hand feed was by engaging a simple clutch; a micrometer stop, mounted in a T slot on the front of the table, was a standard fitting.
The 4H weighed 1757 lbs., the 5H 1875 lbs. and the 6H 2210 lbs
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