email: tony@lathes.co.uk
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TOS Zbrojovka FA4 Milling Machines

TOS FA2   TOS FA3   TOS FA5

TOS FN Universal Millers

An Operation & Maintenance Manual is available for the TOS FA4


From the late 1940s onwards, based in what was then a communist, state-controlled Czechoslovakia, the TOS/Zbrojovka/Skoda machine tool group offered a bewildering variety of products amongst which were dozens of different milling machines. However, one of the most popular and widely distributed was the FA range, consisting of the FA4 (described below), FA2, FA3 and FA5, all conventional knee-type machines with sales handled,  initially, through Elgar Machine Tools of Feltham, Middlesex and then by the much larger Selson Group.
All four sizes of the FA were available in three forms: a horizontal machine the "H"; as a "Universal", the "U" (fitted with a table able to be swung 45 in each direction from central) and as a robust vertical, the "V", that used the table and knee assembly from horizontal combined with a swivelling vertical head whose quill was driven by a fine-feed handwheel - but no quick-action drilling lever. Although all three sizes of machine shared a common layout, there was no attempt by the makers to stretch a smaller model into a larger; each was a novel construction with different main castings, table sizes, spindle speeds, motor sizes and table-feed rates. As was normal on this type of miller from all makers, the Universal was equipped, as standard, with the facility to couple a power drive to both a universal dividing head as well as various sizes of rotary table.
Over the years a number the millers developed and offered in other versions that included the FA3AH, FA3B, FA4AH, FA4B and FA5AH, FA5B; these notes concern only the earlier models.
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TOS Zbrojovka FA4-V Vertical

Continued:
FA4
A considerably more powerful machine than the FA3, the Zbrojovka FA4V, FA4H and FA4U all had a table 315 mm wide by 1600 mm long with three 18 mm T-slots on a 60 mm spacing and both power and "rapid" feeds longitudinally, in traverse and vertically by a separate 1.1 kW (1.5 h.p.) 1390 r.p.m. motor. Rapids were driven from the same motor (flange mounted against the rear of the feed gearbox, itself mounted at the left-hand side of the saddle) with initial drive through a pair of spur gears and then through multi-plate clutches with overload protection - a single spring-loaded directional lever on each axis providing the control. Travel stops were not mechanical but electrical, their activation stopping the motor.
Longitudinal travel was 1010 mm by hand and 1000 under power; respective rates for the cross feed were 365 and 355 mm and vertically 435 mm and 425 mm. 15 rates of power feed were available, these ranging from 10 to 1250 mm/min both longitudinally and across - the full range being: 10, 14, 20, 28, 40, 56, 80, 112, 160, 224, 315, 450, 630, 900 and 1250. Vertical rates were set at 25% of the others, being from 4 to 250 mm/min. Rapid traverses were set at 2800 mm/min longitudinally and across and at 800 mm/min vertically. Table power-feed controls - selection of direction, engagement and rate were all duplicated at the rear of the saddle at its right-hand end, so allowing the machine to be operated from the rear of the table - a possible bonus on some long or awkwardly-shaped jobs. An added and rather unusual safety feature was a pair of illuminated arrows that indicated the direction of table travel selected
Positive lubrication of the feed speed-change gearbox was by a piston pump, the recirculating supply also able to be directed (unfortunately not automatically but by pressing a handle), to send oil to the table feed screws and their support bearings and the sliding surfaces of table, saddle and knee. The heavily loaded knee screw was lubricated by an oil bath and, copying established Cincinnati practice, when normal or rapid feeds were engaged by a circulating supply.
Both horizontal and vertical spindles were mounted on their noses in a precision-grade, double-row roller bearing with a tapered bore that allowed a very precise adjustment to be made of the running clearance. Listed as standard was an ISA70 spindle nose fitting, with the option of a Metric 50 - though doubtless others would have been supplied to special order and may well be found on second-hand machines. On horizontal machines the makers offered the option of a spindle fitted with a flywheel, the intention being to make it more suitable for use with cemented carbide tipped blades.
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TOS Zbrojovka FA4-H Horizontal

Continued:
Able to be swivelled 45 each side of upright, the vertical head had a quill with a fine-feed travel of 85 mm with, instead of a screw-type adjustable depth stop, a telescopic design that was also connected to a dial indicator. In addition, for very precise work, it was possible to fit slip gauges into the stop mechanism.
Drive to both horizontal and vertical spindles came from a low-profile, 1430 r.p.m.  7.5 h.p. motor flange mounted against the rear of the main column with control by a forward-reversing switch and "Start-Stop" push buttons. Two electrical options were available: a 10 h.p. motor and an "Alnico" brake system where holding down the "stop" button brought in an electrically applied braking effect created by a rectifier supplying direct current to the motor. Motor overload protection was by thermal relays and the operator provided with an Ammeter to gauge how hard the machine was working.
Twelve spindle speeds were supplied, these being generated by a gearbox held within the main column and operated by two levers: one rotary the other quadrant. The speed range was identical for all three models: 32 to 1400 r.p.m. as standard but with the option of higher range that spanned 45 to 2000 r.p.m. Standard speeds were 32, 45, 63, 90, 125, 180, 250, 355, 500, 710, 1000 and 1400 r.p.m. and the higher range: 45, 63, 90, 125, 180, 250, 355, 500, 710, 1000, 1400 and 2000 r.p.m. A useful addition on such a large machine was the inclusion, as part of the standard specification, of an inching button - the makers also offering, on machines intended single-piece work (where changes of spindle speed might be very frequent) an automatic speed changing mechanism, this consisting of an electric motor controlled by a lever on the right-hand side of the distribution box. When a customer opted for this device the normal speed-change lever and inching button we no longer supplied.
Lubrication of the speed-change gearbox, spindle bearings and bevel drive to the vertical head was by an electrically driven gear pump, the flow from which could be checked (on some machines, but possibly not all) by a sight glass on the column's right-hand wall.
Coolant was held in the hollow foot of the miller and supplied by an electrically-driven pump. Returning coolant and chips were drained from the table and saddle through broad channels in the knee and then into detachable pans at either side (these holding coarse separator screens), before returning to the base where the compartment was divided into a number of settling tanks.
Electrical contactors, fuses and associated hardware were grouped together in a compartment at the back of the machine, the whole assembly being mounted on a neat, slide-out tray.
Supplied as part of the standard equipment with each new machine were the following: a milling arbor, coolant equipment, a complete electrical installation to the customer's voltage requirements, two grease guns, a set of spanners and an instruction book.
A number of useful extras was offered including a power-driven universal dividing head with tailstock and a support for long work, a power-driven rotary table and, for the horizontal models, standard, universal and circular vertical attachments, a rack milling device and a circular attachment with hand drive. In addition the usual range of machine vices, different diameters and lengths of milling arbor, spindle-nose reducing sleeves and collet chucks, etc.

TOS Zbrojovka FA4-U Universal

Knee assembly as used on the swing-table FV4U Universal miller


TOS FA2   TOS FA3   TOS FA5

TOS FN Universal Millers

An Operation & Maintenance Manual is available for the TOS FA4

TOS Zbrojovka FA4 Milling Machines
email: tony@lathes.co.uk
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