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A product of the U.S.-Burke Machine Tool Co. of Cincinnati, Ohio, the "Millrite" was designed as a low-cost competitor to the established Bridgeport and other high-class makes of turret milling machine, the Millrite was of essentially simple but strong construction and offered - on the basis of one main column - several alternative head, ram and table assemblies.
With hand-feed only, the standard model had a table with a working surface 7" x 27" with 16" of longitudinal travel - though longer examples of 8" x 32" and 8" x 36" - with travels of 21" and 25" respectively - were also available to special order. A variable-speed power feed kit was available (but only sold for factory fitting to new machines) which gave feed rates from 1" to 18" per minute. The micrometer dials were large, (3.5" in diameter) and calibrated exclusively in English units - there being no sign of a metric option in the accessories' list. The feed screws were of generous proportions, a full 7/8" in diameter, of Acme form and running through bronze nuts. The cross feed travel of the table was a useful 8" - whilst the head could also be moved in and out of its swivelling support through a range of 12.5". The combination of these movements meant that a standard machine could bring its cutter as close as 4" to the main column yet reach as far away as 16.5" (with corresponding figures of 6.5" minimum and 17" maximum for the Compound-swivel ram machine). With the head set to swivel, the cutter was able to sweep along an arc with a maximum radius of 25" (12.5" minimum) and cover, in conjunction with table's longitudinal movement, a length of some 62".
With the quill retracted, and the knee lowered, a maximum clearance of 17.75" was available between the spindle nose and table - although 5-inch raiser blocks were available to increase this as required.
Fitted as standard with as simple, V-belt drive head powered by a 1 hp, 1800 rpm motor, six well-spread spindle speeds were available in each direction of 335, 575, 970, 2550, 3075 and - very useful for running smaller cutters - 4535 rpm. However, at least three different motors are known to have been offered: a 0.75 h.p. with speeds from 250 to 3400, a 1 hp 1200 rpm unit that gave 250, 430, 725, 1160, 2300 and 3400 rpm - and another 1 h.p. type of 900 rpm with a range of 185, 320, 540, 860, 1700 and 2500 rpm.
A "High-speed" head was also listed, but details of this are sketchy; it is known to have been fitted with an all-ball-bearing spindle - rather than the combination 5-bearing taper-roller and ball bearings of the ordinary unit - but its motor rating and speed range are not known. If any reader is able to provide details of this head - or additional information generally about the Millrite - please do get in touch.
With just a short V-belt from motor to quill, the resulting concentration of mass at the front of the ram was mitigated to some extent by the length of the ram's engagement with the top of the column - for even when fully extended approximately half its length was still fully supported within the V ways. Unfortunately, when the head was required to be set at an angle, controlling the combined mass of head and motor - whilst maintaining the desired angle and tightening the clamping bolts - was not easy. The quill - which could be ordered with various internal tapers including a Brown & Sharpe No. 9 (standard), B & S No. 10, R-8, 30 International and No. 2, 3 or 4 Morse - was fitted with fine down feed as standard with the option of a quick-action rack feed for drilling purposes. The Millrite could also be fitted with attachments giving variable-speed power feed to the quill, the longitudinal travel of the table and the vertical movement of the knee; it was possible to include all three units on one machine. The head with a power down-feed quill used a separate motor, attached to the back of the ram, to provided an infinitely-variable drive that gave feed rates from 0.5" to 2" per minute. The power could be knocked off manually at any point, or an automatic trip, positioned on the front of the head, used instead.
Stiffened internally by a continuous ziz-zag brace, the ram was of two types: a standard unit with the swivelling head mounted on an large, integral flange and a rather more versatile type where the head was fastened to a swivel bracket that allowed a range of "nodding" movements. In combination with the standard swivel head, this ram allowed a cutter to be manipulated into almost any position.
For a miller to standard specification the floor space required was approximately 60" x 50" and the weight around 1100 lbs.
If any reader has a Millrite with a different specification to those outlined the writer would be pleased to hear from you..
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