A conventional but very heavy (3200 kg/7000 lb) "Universal" horizontal milling machine, the Simplon UM had its separate base and internally ribbed column cast in Meehanite iron, the fine grain structure of which promised superior strength, minimum friction on the slides and resistance to wear. Also in Meehanite, the knee was a substantial one-piece, box-type casting designed to have as large a surface area as possible to support the saddle and so reduce vibration and flex. Fitted as standard was a 1600 mm x 360 mm (63" x 14.25") table able to be swung 45° each side of central and with three 16 mm T-slots (0.63") wide on a spacing of 60 mm (2.4"). Table travels under power (using a 3 h.p. motor built into the knee were 1150 mm (45.3") longitudinally, 360 mm (14.2") in traverse and 500 mm (19.7") vertically. By hand the travels were slightly longer being, respectively, 1170 mm (46"), 370 mm (14.6") and 525 mm (20.7"). The horizontal hand-driven feed was by full-circle handwheels at both ends of the table while for traverse and vertical movements a  pair of sockets on the front of the knee took a detachable crank handle. Selected by a single dial-type, direct-reading control on the front face of the knee, twelve rates of power feed were provided ranging from 10 to 820 mm/min (0.4" to 32.3") for the longitudinal and across and at half those rates vertically. Rapids, working through a multi-disc clutch and controlled by a long lever pivoting from the knee's right-hand face, were included as part of the ordinary specification having a rate of 2500 mm (98.5") per minute horizontally and in traverse but, for safety and finer control, at half that rate vertically. All gears in the power-feed drive system were in a heat-treated, case-hardened, nickel-chrome steel and lubricated by an oil bath.
Driven by 10 h.p motor the Cr-Ni-Mo spindle ran in adjustable taper-roller bearings, carried an ISO 50 nose and could be moved so that its centre line was a maximum of 525 mm (20.7") away from the table. Controlled by a combination of a direct-reading dial and lever on the right-hand face of the main column, eighteen speeds were available that spanned 25 to 1650 r.p.m. or, as an option, 30 to 2000 r.p.m.
Available as part of the optional equipment were a pair of plain (non-quill-feed) and universal vertical heads driven from the horizontal spindle with step-up gearing that gave speeds 25% faster than the horizontal. Either head, when supplied, was permanently fitted to a swing-arm carrier that allowed it to be mounted and removed with the minimum of effort.
Unlike smaller models of Simplon milling machines, a number of electrical controls, including those for the feed direction start, stop and reverse, were mounted on an adjustable, swing-out pendant.
Supplied as part of the standard specification were the following: a complete electrical installation, a horizontal cutter-holding arbor, a hand-crank lever for the traverse and vertical feeds, a set of spanners and an instruction book. The usual range of extra was listed including plain and universal vertical heads, induction hardened ways, a slotting head, various diameters of cutter-holding arbor, micrometer boring heads, optical positioning systems (these models came before the easy availability of Digital read-outs), standard and universal dividing heads, rotary tables in several sizes, inclinable supplementary tables, an assortment of machine vices, guideway guards and a work lamp..