Continued:
Over the years the FP1 was to be built in three versions, each easily distinguished from the others: the Mk. 1 of the early 1950s had lever-operated engagement of spindle speeds (by the juxtaposition of two controls on the right-hand face of the column) but changewheels (inside a case on the right-hand side of the column) to vary the rate of table power feed; the Mk. 2 of the late 1950s used levers to alter both speeds and feeds whilst the Mk. 3, introduced during the early 1960s, was fitted with more convenient and modern-looking dial controls.
General Layout
Constructed in an ingenious way, the layout of the spindle-drive system was both compact and effective: the top of the main column was machined as a slideway to carry a separate housing that doubled to mount a horizontal milling arbor and also act as a base for the various heads or a horizontal milling overarm. The chrome-nickel alloy spindle was case hardened and ran in bearings that provided both excellent support and an easy means of adjustment. To solve the problem of how to drive the spindle when its housing was moved forwards and backwards (to provide lateral travel to the cutter), a long fixed gear was mounted parallel to and beneath it on the final-drive shaft and the upper gear allowed to slide along it. A word of warning for users of the English-made Alexander "Master Toolmaker" who might want to fit a Deckel head - the Alexander drive gear has a 21-degree pressure angle whilst that of the Deckel is 14.5.
Besides normal horizontal and vertical milling operations, all models were available with a range of accessories to cover slotting, jig boring, jig grinding, spiral milling and punch milling. In respect of these operations, an important part of the machine's versatility was dictated by the multi-angle, swivelling and tilting table; with just the plain table in place the miller remained very desirable, but it was not possible to enjoy in full all the FP1's ingenious capabilities.
Drive System for Head and Table
Cleverly arranged so that the table-feed rates were completely independent of spindle speeds, the drive system on the Deckel began with a two-speed, 3-phase motor mounted at the back of the machine on an easily reached, completely open and height-adjustable cast-iron platform. The table-feed gearbox was mounted inside the column, below the spindle-drive gears, and had eight speeds; used in conjunction with the two-speed motor this arrangement gave 16 feeds, the fastest of which, the makers suggest, was quick enough to used in place of a power "rapid-traverse". Whilst the rate of table feed was set by either pick-off gears or (later) two levers or a dial, on all versions the direction of movement was controlled by an unusual (for a machine tool) ball-handled rod, rather like a car gear-change lever. The lever controlled the movement of the main "vertical table" through eight different directions - left, right, up, down and a further four combinations where, with both horizontal and vertical feeds engaged at once, the table would move diagonally at an angle of 45 degrees. The table feed screws were all precision ground, ran though large bronze nuts and were fitted with exceptionally clear, finely engraved satin-chrome finish micrometer dials. Built-in steel rulers were provided for each axis of movement which, in combination with holders to accept dial-test indicators and gauge blocks, allowed high-precision measurements by co-ordinates to be made, independent of the feed screw readings. All table movements (around 300 mm longitudinally and 340 mm vertically) were fitted with automatic tripping stops with the upper one, to limit the table's vertical rise, fitted with micrometer adjustment. On the earliest model, to protect the table-drive mechanism against overloads, a shear pin was fitted hidden under a slip spring above the coolant pump. All gears, and their shafts, both spindle and table drive, were hardened and ground-finished. The "Y" movement was, of course made by the head, the travel being in the order of 150 mm.
Heads
Several types of vertical head and cutter supports were available: a standard overarm and drop bracket to hold a horizontal milling arbor; a standard Vertical Spindle Head, powered by the machine's own drive system; a High-Speed Vertical Spindle Head with its own motor; an Angular Spindle Head driven from the main motor and designed to assist with the milling of hard-to-get-at sections; a Corner Milling Spindle with its own motor and a swivelling, belt-driven end tip intended for machining internal corners and edges - and a rare Precision Boring Head from the LKB Optical Coordinate Jig Boring Machine. A simple Slotting Head was also listed.
Vertical Heads
Usually ordered with every machine as a standard accessory, the ordinary vertical head could be swivelled through 360º and was equipped with a (rather short) 2.375" (60 mm) travel quill carrying a No. 4 Morse or 40 INT nose. The maximum clearance between spindle axis and inner face of the main column was 11 inches (280 mm). Unfortunately, the head had exactly the same range of 16 speeds from 40 to 2000 rpm (or 95 to 1900 r.p.m) as the horizontal spindle - a range that (compounded by a very short lever and small knurled-edged handwheel to move the quill) limited its ability to use very small cutters. To get round the problem Deckel offered an alternative head, the "High-speed", powered by a 0.75 h.p. 3-phase motor that gave six belt-driven speeds from a low of 1900 to a maximum of 6000 r.p.m. Fitted with a 40 INT nose the head could be swivelled 45 degrees either side of central and, because the unit was self-motorised and did not require the usual gear drive, the base was able to be made extra long to provide a useful 7.875 inches of extra travel and an additional 4" of clearance from cutter centre to the column face. Unfortunately, instead of equipping the High-speed head with a long-travel quill with fine-feed control, Deckel used the same annoyingly restricted unit from the standard head - a design decision that any operator charged with the delicate handling of small cutters would have found most frustrating.
Continued below:

Continued:
Angular Spindle Head
An interesting accessory, designed to machine into places that would otherwise have been impossible or very difficult to get into, the Angular Head was fitted as standard with a No. 1 Morse taper socket into which a variety of special or standard cutters could be mounted. The head could be swivelled 360 degrees about both its longitudinal and vertical axis, so allowing the tool to be set at any desired angle "in space" - not quite up to the ingenious flexibility of the system used on the (very much heavier) French-built multi-swivel Hure miller, but not far off.
Corner Milling Spindle Head
Another unit intended for use in workshops producing mould and die tooling where access to internal corners and edges was difficult. The spindle carrier assembly could be rotated through 360 degrees about its vertical axis, whilst the cutter-spindle proper could be twisted through an angle of 90 degrees. A single-lip cutter was usually used, ground specially to shape for the job required. Driven from its own 0.55 kW motor, a round drive belt, with a pair of jockey pulleys to keep it in proper contact with its pulleys, passed down the length of the column and drove the spindle head directly. Because only very small cutters, required to run at very high speeds, were employed, just two speeds of 4000 and 6000 rpm were provided.
Precision Boring Head.
Lifted from an accessory range intended for the Deckel LKB Optical Jig Borer, and offered on all sizes of FP millers, the unit for the FP1 required the use of an intermediate gearbox. The head, as might be expected, was intended for very close-tolerance boring work, especially on proper jib-boring operations in conjunction with Deckel's own optical or standard measuring systems. The spindle ran in specially made, high-precision ball bearings and had 21 speeds and 6 rates of feed. Coarse setting of the head was made by hand against a graduated scale, whilst fine adjustment was through worm gearing against gauge blocks and dial-indicator readings. The head could be tilted through 90 degrees in both directions.
Slotting Head
The swivelling slotting head is one of those accessories that can sit unused on the shelf for months, but, when needed, is an invaluable tool. Eleven ram speeds were provided ranging from 16 to 200 strokes per minute. The ram stroke, the setting of which was read from a graduated scale, could be adjusted between a travel of 0 to 80 mm (31/8").
Buying an FP1
There are a few general points worth considering when looking for an FP1 or similar miller. Used examples are now available very reasonably, and it's possible to invest in an example with basic equipment, in sound working order, for little more than the price of a new, but larger Far Eastern machine of indifferent quality. Unfortunately the various accessories (especially the high-speed and slotting heads and various dividing attachments) are very sought after, and command high prices; however, once acquired they are a solid investment and easily sold on when no longer required.
Being relatively complex machines, with finely made parts, dismantling requires a certain mechanical sympathy. Be suspicious of any example that shows evidence of rounded nuts, hammer blows to any of the casings or other signs of brute-force intervention - it may have been through the hands of a mechanical incompetent and suffered hidden, serious and expensive-to-put-right damage. The joy-stick lever should slide without undue force through its gate - if it has to be wrenched, something is amiss.
The FP1 was developed into the larger and mechanically very similar FP2 and FP3 Series machines with the former, in many respects, identical to the FP1 and with most of the foregoing FP1 notes applicable to it. However, the FP3 Series, made until the late years of the 20th Century, included some rather different, specialised versions and none of the FP1 and FP2 accessories able to fit.