Hornamill milling attachments were manufactured by The Hornamill Machine Tool Co. Ltd. of 4, Royal Parade, Dawes Road, London S.W.6. It appears that they survived until the early 1970s, though by then demand for their limited range of products must have been slight.
So far, two main items by Hornamill have been discovered: an attachment to convert a horizontal milling machine into a vertical by a head that clamped to either a round or dovetail overarm - and an ingenious, self-powered lathe attachment. The milling machine accessory was of the same type as made in the United States by Bridgeport in the late 1930s and those from Tree, Halco, Kerney & Trecker and Dalrae.
Of a similar form to the better-known American Globe, the lathe attachment was constructed as vertical slide and called, by its makers, the "3-Way". It was intended for use on lathes with a centre height of 7 inches or greater and appears to have gone through several evolutionary stages, the final models being designated by the ratio of the drive fitted. Models available just before production ceased were the Plain Types Mk. 9 8:1; Mk. 9 12:1; Mk. 9 Low Speed and two versions on which the front section could be swivelled 20?each side of central, the Mk. 9 SF with a 12:1 ratio drive and the Mk. 9 SF/LS with extra low-speeds. How earlier versions might have differed from the last types is not, unfortunately, known.
Heavily built, the slide unit carried a standard, foot-mounted 1 h.p. 3-phase motor that drove not one, but two Timken taper roller bearing supported spindles with, on the Mk. 9, each having a No. 3 Morse taper socket. One spindle was arranged for high speed and the other for low with, at its outer end of the latter, a 2.5-inch long by 1-inch diameter stub arbor that could mount side-and-face and slitting saw cutters. Unlike the Globe, the (eight-speed) drive was by easily changed pick-off gears, not belts, so eliminating slip when being used towards the limit of its capacity ("pick off" gears are arranged in pairs and mounted on fixed centres). Weighing a considerable 112 lbs (51 kg), the unit had a vertical travel of 7 inches driven by a screw fitted with a micrometer dial graduated to show a slide travel of 0.001" (0.025 mm).
Speeds on the standard Mk. 9 8:1 version were 2500, 1860, 1200 and 850 r.p.m in high range and 310, 230, 150 and 106 r.p.m. in low. The Mk. 9 12:1 ran the same high speed set with a slower range of 210, 152, 98 and 72 r.p.m. The Mk. 9 Low Speed had a high-speed set of 1250, 930, 600 and 425 r.p.m. and a slow of 155, 125, 75 and 52 r.p.m. The swivelling Mk. 9 SF used the same speed range as the 12:1 ratio version and the swivelling Mk. 9 SF/LS the same range as the Low Speed model. As the drive was by pick-off gears, the speed range was simple to change and the makers offered unspecified sets to produce almost any that a customer required.
In use the "3-Way" was bolted to the lathe's cross slide or, on larger machines, to the top slide (this usually requiring some work) and then set so that the horizontal spindle was, viewed from above, in line with the lathe's bed. With the low-speed spindle in use a variety of operations could be carried out including thread and worm milling, circular grooving on bars held between centres and circular recessing and cam milling - the full extent depending upon the ingenuity of the operator. When mounted in the same position, the high-speed spindle could mill slots and perform tasks using end mill cutters along the top, bottom and centre sections of shafts tackling such jobs as woodruff and flat keyways and splines. With the attachment rotated through 90? either left or right, the low-speed spindle was presented at right-angles to the lathe's centre line. Set in this way shell mill and similar cutters could be fitted to the low-speed spindle and the lathe's carriage drive used to machine flats.
If you have a Hornamill machine tool of any type, the writer would be interested to hear from you..