Hayes were a small but respected Leeds-based company founded in about 1930 by George Hayes, a practical engineer of great skill whose original interest (and one that involved the company for may years), was the production of dies for dies-casting machines. The firm was to be eventually run by his son, Gerald, until a management buy-out in the 1960s. Besides work for die-casting companies and the production of numerous specialised, one-off machines, Hayes were famous for their very high quality precision milling machines including the "Tracemaster TM54" range of two and three-dimensional copy profile millers, the "Tapemaster 1380", an early numerically-controlled vertical miller; the "Gemini" automatic miller; the "Tracemaster TM43 and TM43-3D" two and three-dimensional copy-profile millers built for exceptional accuracy and with either hand or automatic guidance;  the "Linemaster", a two-dimensional precision copy-milling machine with Linerider optical following equipment able to work from a line drawing; the "Tapemaster 1090", a vertical milling machine controlled in the usual two axes but with control of the third from pre-set trips and tapes and the "Economill", a very heavily built precision profile miller.
The company's smallest conventional machine (and the one most likely to be encountered today) was the "The Diemaster Universal Die and Mould Milling Machine" - a machine distributed during the 1950s and 1960s through Dowding & Doll Ltd. of Greycoat Street, Westminster, London S.W.1. The Diemaster, typical of a Hayes' product in being directly associated with the top-quality toolroom work and carefully thought out in every detail of its design, was superbly constructed (alignments were to within 0.0002" per foot) and mounted on a substantial cast-iron base that held, in its rear section, a 1 h.p. 1425 rpm 3-phase motor. Twin V belts took the drive from the motor to an integral 9-speed gearbox with ball-bearing supported shafts and nickel-chrome gears; speeds were changed by twin-lever concentric controls mounted on the right-hand face of the main column; from the gearbox the drive was taken up to the ram by a wide flat belt on early machines and four V belts on later versions. The very useful spindle-speed range ran from 50 through 100, 150, 200, 400, 600, 800, 1600 to 2400 r.p.m. As a point of interest, once all the adjustment of the belts has been used up, or the belts deteriorate, replacing them is a straightforward procedure - providing you have a copy of the workshop manual; the best type of belt to use is the sort that can be found here.
The ram slide, fitted with a capstan-handle operated rack-and-pinion drive and linear vernier scales, could be wound in and out over a range of 7 inches. The head, which swivelled through 360 degrees, was equipped with a 2.5-inch travel, No. 2 Morse taper quill with a wheel-controlled fine feed on the right-hand side and a quick-action drill-feed lever on the left. Both the head spindle and its horizontal drive shaft were made from hardened and ground 'nitralloy' steel running in pre-loaded ball journal bearings with the right-angle drive into the head through nickel-chrome spiral bevel gears. The direct-fitting, draw-in collets used in the head had a maximum through capacity of 0.5".
A large weight inside the column balanced the knee assembly and made its elevation a remarkably light and simple one-handed affair; access to the weight allowed it to be adjusted if a very heavy job was mounted on the table. The 5.5" of traverse and 12" of longitudinal travel of the 21" x 6.5" table were similarly smooth and easy - the feed screws passing through pre-loaded ball thrust races in their support plates at each end of the table and on the face of the knee. As an option a larger table was also offered - though few have been seen - some 28" x 8.5" and with the longitudinal travel increased to 16 inches but that in traverse unaffected. The larger table can be immediately distinguished in photographs by a cast-in coolant trough around its periphery.
The design of the both table ways was unusual: the traverse was set at two levels with (two) independent gibs (that allowed the clearance to be set with great accuracy) whilst the longitudinal travel was ingeniously arranged with the table-support casting made as long as possible to give the table the maximum support no matter how far out it was moved. In order to obtain a decent amount of travel (though it was still only 12 inches) the sides of the knee casting was formed with large semi-circular cut-outs to let the table feed-screw end plates travel into it right up to the inside face of the balanced handwheels. The vertical travel of the knee was 14" and the maximum clearance between table and spindle nose 19.5".
Combining many of the elements of a small jig borer and a conventional vertical miller the Diemaster makes an ideal machine for the model or experimental engineer who needs to combine, in one machine, strength and rigidity for heavy cuts as well as a sensitivity of touch and the fine accuracy required for smaller, delicate jobs. Production numbers and dates are not precisely known but it is certain that machine No. 222 was built in 1965.
Although very few can have been produced (only one having been recorded in recent years) , there was also a conversion available to horizontal milling. This involved removing just the vertical head and replacing it with a very heavy casting that carried both a dive shaft and twin-bar overhead arbor supports -  the drive being taken from the same shaft. As such, the position of the cutter could be changed by turning the rear capstan handle and the speeds altered as normal..
The miller stood 59" high, was 43" from the back of the stand to the tip of the cross-feed handwheel and approximately 38" wide over the ends of the table's longitudinal feed-screws handles. Its weight was approximately 12 cwt (1344 lbs).
More pictures of a Diemaster can be seen here and here--and an interesting account of working at Hayes here.