email: tony@lathes.co.uk
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Centec Milling Machines
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Early Centec Horizontal   Centec 2C

Centec 2A Photographs  Centec 2A Photo Essay 

Centec 3 & 4 Series & Automil
   
Accessories   New Vertical Heads   Vertical Head Raiser Block   

Available for Centec Millers:
Copies of the Original Instruction Book for the 2A, 2B, 2C & Automill

Well-known since the early 1940s, and still enormously popular today, and the Centec 2, 2A, 2B and 2C (and less well-known 3 and 4 Series and  Automil) milling machines were originally manufactured by the Central Tool & Equipment Company at the "Centec Works" in Maylands Avenue, Hemel Hempstead, Hertfordshire, England. An earlier address, and one that appears on the maker's plates of some early models including the belt-drive Model 2A, was Church Terrace, Richmond, Surrey. This was the site of the Sunbeam Works, and is shown in contemporary Trade Directories as having been occupied by Centec from 1940 until 1956. The building still stands, only partially redeveloped and with part of it housing yet another service "industry" - a Tai restaurant.
Unfortunately, the serial number data for Centec millers is far from complete; the factory never issued complete lists and only US-based "Serial Number" book publishers give any information - and that, I suspect, given its paucity, was given only grudgingly. Hence, it's not unusual to find wide variations on what is shown below:
Serial Numbers recorded are, for the No. 2
1943.....429    1946….738    1949….933    1952….1091    1955….1194    1958….1203
Serial Numbers for the 2A
1946….79    1949….372    1952….1086    1955….1560    1958….1714    1961….1886    1964….2063
Serial Numbers for the 2B
1958….5213    1961….5519    1964….5706
Under the ownership of a Mr Samuels, the millers were of compact design, beautifully constructed and versatile in use - hence, they have long been respected by enthusiasts who appreciate a product of outstanding quality. Lots of handwork are known to have gone into finishing each machine, with hand-scraped surfaces and a final running-in test under power before dispatch. The original design dates back to the early 1940s, when the first model was introduced as a development of the V.E.C. or "Victa" horizontal miller, a machine sometimes badged as a "Warwick". As a point of interest, during the 1940s and early 1950s, Victa also manufactured lathes using the "Warwick" name. Quite different to the rather advanced range of geared-head lathes sold under the "Hobson" brand, this was a machine intended for model-engineering. Backgeared and screwcutting, with a gap bed and using an all-V-belt drive, it had a 3.5" centre height and admitted 18" between centres. Later, having moved to Pool in Dorset, Victa also built the Eagle surface grinder, a model originally manufactured by Dronsfield Brother, makers of Marlow milling machines.
Built from 1943 to approximately 1949, and fitted with flat-belt drive, the original Centec had a 12" x 3.75" table, a round overarm and was a horizontal-only machine - there being no facility to fit a vertical head; the next model. The Centec 2 was a substantially modified machine with the round overarm replaced by a much more robust and rigid dovetail fitting (a move reflected across the industry and caused by the need to stiffen machines to take advantage of new cutting tools that permitted the use of deeper and faster cuts). The dovetail overarm slideways, machined into the top of the column, also allowed the fitting of a vertical head. While the same design of simple, side-mounted countershaft continued in use with flat belt drive, later machines benefited from a change to V belt. In 1949 the Centec 2 evolved into the 2A, with changes that included a slightly larger table of 16" x 4.25" and, of greater importance, a completely revised drive system consisting of a 6-speed gearbox built into the body of the main column. The new drive (with a 0.5 to 0.75 h.p. 3-phase motor) gave spindle speed ranges of: 85, 195, 395, 595, 890 and 1400 rpm or, alternatively (with a 2800 r.p.m. motor), 170, 390, 790, 1190, 1780 and 2800 r.p.m. Some versions have also been found with 1 h.p. 2-speed, 3-phase motors that gave twelve speeds from 85 to 2800 r.p.m. Next, in 1958, came was the 2B - a miller that offered a number of improvements over earlier versions including a much more useful 25" x 5" table and the repositioning of the knee elevation handwheel - from its inconvenient location towards the rear of the column's left-hand face - to the front, where, not only could it be more easily manipulated, but also its action more easily observed. The castings of the 2B were strengthened and the knee benefiting from improved stiffness by being boxed in at the front. The final conventional Centec model was the 2C, this having a 29.5" x 6" table and mounted on a very heavy cast-iron stand.
Table travels of the various models were as follows:
2A - longitudinal 9", cross traverse 4.5", vertical 6"
2B - longitudinal 14" (less 1.25" with power feed) cross traverse 5", vertical 9.5"
2C - longitudinal 14" (including power feed), cross traverse 4.5", vertical 11.25"
2A - maximum distance from spindle centre to table 6.625"
2B - maximum distance from spindle centre to table 10.5"
2C - maximum distance from spindle centre to table 11.25"
For bench mounting the 2A weighed approximately 360 lbs - the 2B 500 lbs and the 2C (a comparatively rare and much more massive model stand fitted with a heftier main column, longer and wider table with a feeds gearbox and only supplied on a heavy cast-iron stand), weighing in at nearly half a ton.
One important and desirable accessory was the vertical head, by which means any ordinary horizontal model from the 2A onwards could be transformed into a very much more useful vertical and (when equipped with the optional swivelling table) a "Universal" model. The vertical head slotted into the same dovetail as the overarm and, being rather short of clearance as standard, could easily be raised in height by using a suitable raiser block with dovetails top and bottom. Three distinctly different versions of the head were manufactured: the first (Mk. 1), was an expensive-to-produce unit that mounted an enclosed bevel box at the back that turned the drive through ninety degrees - from where it was taken by an exposed V-belt forwards to the spindle; the Mk. 2 had its drive completely enclosed within the body but unfortunately, like the first, had no quill feed. The Mk. 3 version (and by far the most eagerly sought after) was a beautifully constructed unit that incorporated both a fine down-feed through worm-and-wheel gearing and a quick-action, rack-and-pinion driven drilling feed by a handle. The change from one type of feed to the other was through an all-metal cone clutch that, if properly set up, could be flicked into and out of engagement with just light finger pressure. The very first versions of this head had two horizontal slots across the bottom of the casting - one closed down by a nut and bolt to set the quill-to-bore clearance, the other equipped with a ball-ended handle to provide a means of locking the quill in the desired position. A picture the only known head of this type can be seen on this page.
As a point of interest, when a Centec is changed from horizontal to vertical drive the spindle will, unless the motor is fitted with a reversing switch, turn in the wrong direction.
While a table power-feed assembly was standard on the 2C it was an option on the 2A and 2B; when fitted four rates of feed were provided: 0.65, 1.19, 2.18 and 4 inches per minute each selected by combining any two from four pick-off gears stored under a cover on the right-hand end of the table. All later Centec millers had large, easily gripped, chrome-plated "balanced" handles on their table feed screws and clearly engraved, angled-faced micrometer dials. Early table feed screws were 1/2" x 10 t.p.i. square thread, later changed to a more robust and longer-lasting 5/8" x 10. t.p.i. - though the thread remained square. Feed-screw nuts on tables fitted with the quick-action, rack-and-pinion lever-operated feed were of the "half" type and, being pivoted and fitted with a cast-in handle, could be quickly dropped into and out of mesh. The quick-feed attachment on early models was relatively crude and used a pinion gear with a tapered end onto which fitted a handle with its mounting boss bored with a matching taper - so allowing the operator to set its position, or leave it loose and hanging down when not in use. A much-improved version, with a circular face ratchet tightened by a knurled ring, was eventually to replace it.
Besides longer tables, the 2B and 2C Models both had a more robust knee, with a front rather than side-mounted operating handle, and a wider cross slide. Because the 2C was intended for heavier work and more rapid rates of metal removal, the top of the main column was machined with a wider dovetail to accept a much heaver overarm. As a consequence, in order to allow the standard vertical head to be fitted, the makers supplied a step-down adaptor plate - a fitting that was thick enough to give the effect of a small raiser block. Although most types of Centec are found fitted to underdrive stands, the 2A was also available as a bench model with a motor mounting provided in the form of 4 raised T-slots cast into the right-hand face of the main body.
Continued below:.

Centec 2A set for horizontal milling.
Note the knee-elevation handwheel at the rear of the column

Continued:
Early stands (even the first under-drive version) were very compact affairs, constructed from heavy-gauge, sheet-steel and very little wider or deeper than the miller's base plate. Later machines were fitted to what can only be described as cavernous stands with enormous chip trays - some of which had wings extending to the full width of the table. These latter types, while ideal in an industrial location, are difficult to accommodate in an amateur's workshop and, as a result, many have been cut down. However, if you buy a Centec on an unmodified stand, before selecting your hacksaw blade it's worth knowing that, even though rather cumbersome, it's still possible to manoeuvre them through an ordinary doorway. All the "large-stand" mounted versions of the miller seen by the writer have been equipped with 3-phase electrics - and a problem can arise when fitting then with a single-phase motor - an annoying drumming noise caused by the stand acting as an amplification box. A simple solution is to slightly pull in the left and right-hand faces of the stand by fitting a length of threaded rod between them. With a couple of nuts at each end to adjust the tension the resonance can, with a little experimentation, be significantly reduced - if not eliminated. Rather than change the motor, it is now far better to take advantage of the falling prices of 1-phase to 3-phase inverters and fit one of those instead.
The 2B/2C was also offered in modified form as the "Automil" and "Automil Duplex", both with hydro-pneumatic drive to the table; each was made in much smaller numbers than the conventional machines and, while the Automil is more commonly found on a heavy cast-iron stand as a conversion from the 2C, it actually began life on the ordinary sheet-steel cabinet as a modified 2B. The "Automil Duplex" must have been an especially low-volume model and was built up from standard Centec components, mounted on a wide stand, and arranged so that parts could be milled simultaneously at opposing ends of the table. Each spindle was driven by a 1 h.p. motor, the table had 14-inches of travel, with a fast traverse in both directions, and a stepless feed rate from 1 to 400 inches per minute.  If you find a standard Automill it is reported to be (though the writer has never attempted it), a relatively simple task to convert it to manual "2B/2C" operation. While the normal spindle fitting (both horizontal and vertical) for the 2B was a No. 2 Morse taper, examples have also been found with a 30 INT, as specified for the 2C and Automill. Another Centec produced in smaller numbers - and one of the last machines made - was the No. 4; this was a much larger and heavier machine than the 2A and 2B and supplied as a horizontal miller only with a program-controlled and hydraulically-powered 10.5" x 40.5" table with 18 inches of longitudinal movement, 7 inches in traverse and 13 inches vertically. Powered by a 1.5 h.p. motor, and using principles outlined in patents (applied for, but either not granted or pursued), the table drive system had a stepless feed rate running from 0.5 to 50 inches per revolution of the spindle with a very high thrust capacity together with a 300-inches-per-minute fast-traverse. Rigid stops with micrometer adjustment collars were fitted at each end of the table to allow precise setting for dead stop and reversing - as might be used in plunge cutting - and the spindle arranged to stop automatically during rapid table returns in either direction. So that the required horizontal program could be quickly and easily set, four slots in the front face of the table were used to house adjustable trip dogs and, to cope with the high rates of metal removal that were possible, one end of the table was left open so that swarf and coolant could drain away quickly into a detachable collector. The spindle was considerably strengthened and enlarged sufficiently to take a robust 40 INT fitting; it ran in three precision bearings with the one immediately behind the nose being a taper-roller bearing with an inside diameter of three inches. Ten speeds were provided, ranging from 50 to 2000 rpm, by either a 3 h.p. or 5 h.p. motor. In line with its intended industrial use, lubrication was provided by a centralised, one-shot, operator-activated system that supplied oil to both slides.
Other specialist versions of the Centec included the 3, 3R and 3P and 3RV and 3V. The 3 and 3R had programmed control of the horizontal table motion - with the R version also gaining a vertical motion to the milling spindle that made it possible to combine more than one consecutive milling operation in each automatic cycle. The 3P had the refinement of a powered vertical head movement continuously controlled by the copy template and tracer valve. Shapes with angles up to 80-degrees from the horizontal, and very slow tapers, could be accurately copied without steps. Fitted with a 34.25" x 11.75" hydraulically-driven  table (8" x 30" working area and 14" of travel), all these models were considerably larger and heavier than the maker's conventional machines. On the 3 and 3R the spindle carried a substantial 40 International fitting and was driven by a 3.5 h.p. motor with an additional 2 h.p. motor to drive the hydraulic pump. An infinitely-variable speed drive was fitted that gave a range of 50 to 1400 r.p.m. or, optionally, 200 to 2000 r.pm. The  3RV and 3V had exactly the same programme controls as the 3 and 3R, but were of vertical rather than horizontal configuration. Their vertical head was of robust construction and fitted with a spindle supported in large, closely-spaced roller bearings and carried a 30 international or No. 3 Morse taper. The head was provided with a small amount of cross movement, operated through a calibrated dial, but this was for setting purposes only. Spindle speeds ran from 73 to 366 r.p.m in low range and 366 to 2200 r.p.m. in high. These specialist Centec machines were expensive: in the 1960s a 2B on a stand could be had for a modest £455; the 3R was a massive £3250 - more than twice as much as Smart & Brown's best toolroom lathe, the 1024
 Besides the machines mentioned, Centec also manufactured a range of milling machine accessories including indexing units and quick-action swivel base vices, a "Senior" router for wood and non-ferrous metals, profile (tracer) controlled millers, auto-pneumatic indexing tables - and could offer complete rotary-transfer machines built to a customer's specific requirements. They also appear to have had a hand in either the development or production of the "Omlor 70", a high-precision, single-spindle automatic lathe advertised for a time during the early 1950s. This lathe incorporated automatic backlash elimination and was able to produce complicated profile parts as well as shafts, bolts, screw and nuts of the kind commonly used in the watch-making, optical, electrical instrumentation and similar industries - if any reader has an Olmar (or an unusual or fine-condition Centec machine tool of any type, the writer would be interested to hear from you.
Whilst the 2A and 2B are the most commonly encountered models, any type of Centec miller is difficult to find. The "C is especially rare, as are the specialist machines which, once their productive life was over, would have been unceremoniously scrapped. The Centec miller, in all its forms, remains a remarkably useful tool - and because there is nothing on the market today which combines the compact nature, versatility and build quality of this lovely machine, they are sort-after on the second-hand market.

Some pictures below are high resolution and may be slow to load

Centec 2B with capstan-handle lever feed to the table and table power feed. Note the knee-elevation handwheel at the front of the machine

A beautifully restored Centec 2B fitted with a reground table, new feed screws and nuts and now in perfect working order

Centec 2B with power-feed table

Table power feed arrangement showing the dog-face pick-off gears that could be arranged to vary the rate of feed. The spare gears were stored in a slot in the left-hand side of the housing.

Centec 2C. The rarest of the conventional Centec millers, the 2C, was fitted to a massive cast-iron stand and, in addition to its larger compound table, also had a wider and much heavier main column and very much more substantial knee.
Because the 2C was intended for heavier work and more rapid rates of metal removal, the top of the main column was machined with a wider dovetail to accept a much heaver overarm. As a consequence, in order to allow the standard vertical head to be fitted, the makers supplied a step-down adaptor plate - a fitting that was thick enough to give the effect of a small raiser block
Note the 4 holes in each corner of the massive base - these are tapped 1" Whit to take eye bolts for lifting.
The miller must not be lifted on the overarm or round the column - the weight of the base can rip out the 3/8" Whitworth bolts that hold it to the column.

Early table longitudinal-feed feed screws were 1/2" x 10 t.p.i. square thread, later changed to a more robust and longer-lasting 5/8" x 10. t.p.i. - though the thread remained square. Feed-screw nuts on tables fitted with the quick-action, rack-and-pinion lever-operated feed were of the "half" type and, being pivoted and fitted with a cast-in handle, could be quickly dropped into and out of mesh.
Centec Milling Machine feed screws and nuts: I'm the owner of the green Centec 2b milling machine (shown above) As no feedscrews or nuts were available in England, I took the parts to a German machine shop in my home town of Solingen - a shop that works with the Wilkinson factory in town (yes, it's a German company!) and which maintains a lot of old British (imperial) machines.  The owner made new feedscrews in stainless steel and cut both X and Y phosphor-bronze nuts (including the much sought-after half-nut) from solid stock - like this.  X-axis feedscrew Euro 240.  X-axis half nut Euro 247.  Y-axis feedscrew Euro.  Y-axis nut Euro 168.
Phone: 0049-212-2308811 (mobile +49-172-2069383).  Email: Dieter.Falkowski@t-online.de
Because he doesn't speak English - and if you don't speak German - call me on 0049-212-818305 or 0049-176-724 83304 or
hugh_allen on Skype and I'd be happy to help you discuss the matter.  You'd have to send your parts - because hardly any two Centec millers  seem to be exactly the same - to be sure that you get the right items.

Table longitudinal-feed nuts with extended arms from a Centec 2B
The arrangement of the longitudinal feed nut on late versions of the Centec 2B was unusual - and of rather crude construction. The arm was arranged with a spring that positioned in the disengaged position - an ideal situation when the power-feed was engaged. However, if manual feed was required the arm had to be lifted and a slot-headed screw tightened - or the arm held up with one hand while the other turned the feed wheel

The rather crude mechanism that held the clasp nut arm in an engaged position

Hole in extended arm to locate the pressure spring

Three distinctly different versions of the head were manufactured: the first (Mk. 1, shown here) was an expensive-to-produce unit that mounted an enclosed bevel box at the back that turned the drive through ninety degrees - from where it was taken by an exposed V-belt forwards to the spindle; the Mk. 2 had its drive completely enclosed within the body but unfortunately, like the first, had no quill feed. The Mk. 3 version (and by far the most eagerly sought after) was a beautifully constructed unit that incorporated both a fine down feed through worm-and-wheel gearing and a quick-action rack-and-pinion driven drilling feed. The change from one type of feed to the other was through a metal cone clutch that, if properly set up, could be flicked into and out of engagement with light finger pressure.

Mk. 1 Head. The vertical posts were designed to carry a sheet-steel cover

Mk. 1 head bevel box

Rare Centec No. 2 with flat belt drive

The much-sort-after Centec Vertical Head Mk 3 with fine down-feed and drilling quill--the earlier Mk. 2 head (offered in later years as a cheaper alternative) lacked any form of quill feed.
The quill had a No. 2 Morse taper - although a few late models are to be found with the much-superior 30 International - a feed of 2 inches with a maximum distance from nose to table of  8" with a No. 2 Morse taper and 73/16" a 30 International. On the Automil (these are more commonly found with the 30 International) the clearance was 107/8" and 12" on the 2B and 2C. The whole head weighed about 70 lbs.
The drawbar was threaded 3/8" B.S.W. and both the plain vertical head - and early examples of the sliding quill head - were produced with the top of the draw-bar thread exposed. This is very dangerous; wisps of hair are magically attracted to the rotating thread - and can quickly lead to the entanglement the whole scalp. If you are using one of these heads either make a secure cover - or get a short hair cut…..

Various shapes and sizes of cover were fitted to guard the belt drive to the head. The one fitted to this machine is a factory standard unit for an early 2B.

- this page continued here -

Early Centec Horizontal   Centec 2C

Centec 2A Photographs  Centec 2A Photo Essay  Centec 3 & 4 Series & Automil
   
Accessories   New Vertical Heads   Vertical Head Raiser Block   

Available for Centec Millers:
Copies of the Original Instruction Book for the 2A, 2B, 2C & Automill


Can anybody help with the dimensions of  the coil spring in the
Centec vertical head? If so, please do email Hugh at: 
hugh@vsla.net

Centec Milling Machines
email: tony@lathes.co.uk
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