Using an infinitely-variable speed spindle-drive mechanism that operated through expanding and contracting cone pulleys in conjunction with a speed-reducing gearbox, the head of the Boxford VM30 miller was capable of being tilted over through 45 degrees either way of central. A friction device was included to help obtain the correct setting - without the weight of the head overcoming the strength of the operator - and a dowel pin used to located the head in its true vertical position. Early versions employed a coil spring to assist with the opening and closing of the driven pulley, later models used a neater diaphragm-spring arrangement. Fitted with a 30 International taper, the spindle ran in "sealed-for-life" pre-loaded Timken taper roller bearings with a 12 mm thread drawbar to retain collet chuicks and other fittings.
Two sets of spindle speeds were available, giving a most useful range between 55 and 2000 r.p.m. Speeds were changed by the simple means of rotating a dial (which incorporated a rev. counter) on the front face of the head. To obtain the range of slow speeds from 55 to 500 rpm, a gear was engaged by lifting then rotating through 180° a knob on top of the head (the advantages of being able to infinitely vary a spindle speed are considerable; it is nearly always possible to obtain a setting which is just right for the job in hand, and the changes can be made both instantly and in very small increments). Unfortunately - as an obstacle to fine work - there was no quill feed on the head - either drilling or fine - all vertical movements had to be generated by elevating or depressing the knee.
With two T-slots, the 21.65" x 5.9" table had 11" of longitudinal travel and 5.5" of cross; unfortunately the table handles were in powder-coated aluminium and, whilst very smart when new, the coating has a tendency to peel off and look very untidy. Power table feeds were never offered - though the writer has seen third-party and home-made units attached, the latter type driven by a 24-volt truck windscreen wiper motor and gearbox. The throat was 11" - as was the maximum vertical clearance between the table and the spindle nose.
Nearly all VM30s were fitted with a 3-phase motor and changing it for a correctly-size single-phase unit (unless you can find one with the same diameter shaft as the original to mount the variable-speed pulley) is difficult; it's far easier (and more efficient) to employ an electronic variable-speed "Inverter" that, in conjunction with the mechanical speed change, gives both a wider speed range and finer control of the speed setting.
Complete on the maker's stand the Boxford milling machine weighed approximately 339 kg (748 lbs)..