An Operation Manual is available for Boko Millers
Boko milling machines were manufactured by Bohner & Köhle, based in Esslingen am Neckar in the Stuttgart Region of Baden-Württemberg in southern Germany. Most were of the large industrial type and shared a common design: a fixed co-ordinate table together with a milling head that could be moved up and down the front face of the main column. While the larger metal-machining models compromised, amongst others, the WF2, F3, F30, and F63, the three smallest machines in the range were not intended for metalworking at all; instead, they were destined to be employed in pattern shops, making complex moulds in wood to be used in the casting industry. Four models are known to have been offered, these being, in ascending order of size and complexity the F0, F1, F2 and F2V. In addition, with the introduction of the F2V, two improved models of the F1 and F2 were announced: the improved F1/Fu and F2/Fu.High-resolution pictures - may take time to open
Equipped with a 27.5" x 17.5" table with four 0.55-inch wide T slots, the table on the F0 had all-manual feeds to the with longitudinal travel of 24 inches, in traverse of 14 inches while the head could be elevated through 8 inches. The table could be swivelled on its central vertical axis and the head, fitted with an ISA30 nose taper, also tilted through 90° each side of vertical.
Driven by a 2-speed 1.5.2 h.p. motor, ten gear-driven spindle speeds were available of 90, 125, 180, 250, 355, 710, 1000, 1400, 2200 and 2800 r.p.m.
The throat from spindle centre to inner column face was 18 inches and the maximum diameter that could be accommodated on the table 51 inches. The all-up weight was 2000 lbs.
Although much larger and, at 4100 lbs more than twice as heavy, the F1 was also an all-manual machine. With travels of 39 inches, longitudinally and 24 inches in traverse, the 39.5" x 25" table was machined with six 0.7-inch wide T-slots and fitted with an effective automatic roller blind that guarded both the table's longitudinal feed screws and sliding ways. The maximum diameter that could be held on the table was 62 inches.
Power rise-and-fall, controlled by a 0.5 h.p. motor, was fitted to the No.4 Morse taper head at a fixed rate of 79 inches per minute, the travel range being 12 inches, the throat 24 inches and the head able to be tilted 90° each side of vertical. With power coming from a 2.5/3 h.p. motor, seven spindle feeds were available of 45, 90, 180, 360, 720, 1400 and 2800 r.p.m.
Intended for the heaviest work, the Boko F2 weighed 6380 lbs - 2.85 tons - and had a 47.5" x 27.5" table with six 0.7-inch wide T-slots and travels of 47.5 inches longitudinally, 31.5 inches in traverse and a head with a vertical travel 12 inches. Although the table's cross-feed was manually operated, the longitudinal and rotation movements were both power-driven, from a 0.75 h.p. motor, at infinitely-variable rates, the former being from 8 to 79 inches per minute and the latter from 8.7 to 87 inches. Each travel was also equipped with a rapid-feed at the single fixed rate of 98 inches per minute for the longitudinal feed and at rotary (at a limit of 39 inches in diameter) 106 inches per minute.
Fitted with the same vertical head and drive motor as the F1 - and so having the same travels and feed rates - just a more powerful 1.1 h.p. motor was fitted to the elevation drive.
Fitted with the table as the F2 and having the same travel lengths, instead of manually operated power traverse feed, the F2V had this power driven at an identical variable as the longitudinal feed of 0 to 79 inches per minute. The rotary speed was also slightly modified - though again limited to workpieces no more than 39 inches in diameter - this being 0 to 87 inches per minute. Rapids were fitted to all the table feeds; longitudinal and traverse being set at 78 inches per minute and circular at 86.6 inches per minute. Table drive motors were increased in power compared to those used on the F2; that driving the table's longitudinal and rotational feed being 1.5 h.p. and that for the traverse feed, also 1.5 h.p.
Driven by a 2.5/3 h.p. motor the head had the usual No.4 Morse taper spindle and speeds through reduction gearing of 45, 90, 180 and 355 r.p.m. and by direct belt drive of 355, 710, 1400 and 2800 r.p.m. The standard height capacity of the miller was 30 inches, though this could be increased by the provision - at extra cost of course - of a taller main column. The FV2 weighed 9030 pounds. Details of the F2V on this page.
The metal-working versions, the WF2 - and especially the F3 and F30 with their column able to be swivelled around on the base casting - were highly versatile machines. They had cutting heads that could be swivelled and fitted with various right-angle milling spindles, work tables that swivelled and, in addition for special-purpose work, optional extra-height columns. The result was a range of machines that could undertake an almost bewildering variety of complex machining jobs on both ordinary and complex shapes. The extent to which they could be adapted is shown, using an F3 as an example, on this and one other page; their specifications and technical details can be found by following the hyper links at the top and bottom of each page.