Black crackle finish Emco Unimat Mk. 1 (possibly a Mk. 1a) in cast-iron
Although an almost continuous series of small and larger changes altered many details of the lathe's construction and appearance, the general arrangement of all models was identical: a pair of bed bars was carried between supports formed at each end of a "bed tray" that was made first of cast iron, then a heavy zinc "ZAMAK" alloy and finally a much lighter grade of ZAMAK. To discover which is which invert the machine and look at the underside of the bed: a single large "X-shaped" stiffening web denotes cast iron; multiple X-shaped webs indicate a bed in ZAMAK. To distinguish between the lighter and heaver ZAMAK versions (unless you have two to hand and can pick them up) examine the area where the milling post comes through - on the lighter there are six bracing ribs around the hole and on the heavier there is just one round boss in the middle of that rib towards the front; on a light base, 5 of the 6 ribs have round bosses while the 6th, towards the tailstock, does not. The heavier base, having a much higher zinc content (hence the weight), meant that it could be subjected to "plastic cold flow" if left under constant stress. Owners have seen this phenomena exhibited in a Unimat left in the vertical mode for many years where the hole in the base was so deformed that the column was no longer truly vertical. Could the change to the lighter, higher-aluminium content base have been due to this or, much more likely, cost savings?
A central leadscrew was used to drive the carriage up and down the bed rails. Although at first the carriage had no form of lock, later models were given a clamp bolt at the rear that also acted as a form of adjustment to the sliding fit. The cross slide followed the same design and, just like the English Drummond Little Goliath of 25 years earlier, ran on two bars instead of conventional machined ways. The headstock could be swivelled on its mounting and, fastened to its end face (and so rotating with it), was an aluminium bracket that carried the motor and (on most versions) an additional speed-reduction pulley. By reversing the pulleys, and rearranging the belt runs, 11 speeds of approximately 900 to 7200 r.p.m. could be obtained.
With its unique headstock design, ingenious drive system and clever accessory mountings everything points to the lathe being designed from the outset as a multi-purpose machine that could be gradually equipped with a range of profitable extras to allow its use as a metal or wood lathe, miller, drill press, polisher, grinder, jig saw, saw bench, wood planer or jointer, sander or even - with the headstock detached from the bed and fitted with a grip - as a hand drill. The conversion process from one mode to another was generally well thought out and simple to execute: for example, to complete the important alteration from turning to milling and drilling, the headstock, complete with its motor-drive system, was removed from the bed and remounted on an aluminium bracket carried on a 24.5-mm diameter steel bar that plugged into the hole formerly occupied by the headstock's mounting stud. As a note of interest there were at least two designs of vertical column and methods of locking them in place: the later type had a groove was machined round the shaft with a blind hole, bevelled at its entrance, against which the locking bolt pushed. On earlier examples the hole was drilled though the shaft and a different type of locking bolt used.
In order to provide a vertical feed, the 12 mm threaded headstock spindle and its bearings were mounted within a cylindrical "cartridge", with a rack, formed along its rear surface, engaged by a splined bar inserted into a hole bored through the top face of the headstock. By this means the cartridge, under the tension of a large spring, could be propelled in and out of the casting by 5/8" or so - a movement that was also employed to help accommodate various accessories when in the ordinary lathe mode. The first kind splined drive-bar used to move the cartridge was fitted with a very short, plain handle but later a black knob was added and finally the handle (retaining the ball), was lengthened. To excite the anoraks amongst us, some 6 variations on the handle have so far come to light. Although the exterior dimensions of the cartridge were one of the few things to remain unchanged throughout production, its contents did not. The first example used a crude system, similar to that employed in a bicycle hub, with crowded (loose) balls contained between cones with the single-groove drive pulley held in place (overhung, at the left-hand end of the cartridge) by an M12-1 nut, the adjustment of which was used to set the bearing pre-load. The outside face of the front cone was ground to an abutment flange for items screwed onto the spindle nose - although this arrangement may have caused problems with the bearing adjustment, with heavier interrupted cuts tending to tighten the cone and reduce clearances. Later arrangements were more sensible and robust, with the use of two single-row, self-adjusting sealed-for-life ball races (NSK Bearings part number E13-305) and with wavy "Belville" washers providing the thrust. An alternative precision cartridge, the "Clockmaker's Sleeve Order No. 1022" was also eventually offered; this was designed to appeal to workers dealing with very small components, and accepted tiny B8 collets. As a point of interest, the spindle from this unit was also used in the Toolpost Grinder (part number VS2-460) that Emco offered for their larger V7, V8 and V10 lathes.
In order to form a chronological sequence, and so help owners categorise their lathe, the various changes to the cast-iron models (in so far as they have been discovered) will be listed as "Mk. Numbers". It must be emphasised that the manufacturer did not use these, nor were the alterations given any publicity at the time. It is also possible that the lathes inspected may have been upgraded or modified - and it is entirely possible that some of the following conclusions are incorrect.
Unimat Mk. 1a: the first production machines are very rare, and this model is the earliest known example on which research can be based. Despite being intended as a mass-production unit evidence from these specimens shows that, at first (no doubt because of the still-severe economic conditions at the time), the Emco factory would have had a limited number of automatic production machines and a good deal of hand-work went into each example. There is also an indication that little time or material was wasted with, for example, the castings having an indifferent cosmetic finish and wrongly spotted and partially-bored centres holes corrected - but with the initial damage to the component ignored. As it would have provided the easiest and most reliable route into production the first version (like nearly ever other amateur lathe of the time), had its base and other major castings in iron. The first lathe, with an overall length 16-inches, was shorter than later versions and the base unit just 123/8-inches from end to end that allowed a capacity of only 5 inches between centres. Unique to the first one or two years of production the base's other main identifying features were its middle section, formed into a convex chip tray (with a flattish bottom), raised ridges running along the front and back walls and the boring of the casting at both ends to accept two solid-steel, 12-mm diameter bed bars each retained by a horizontal grub-screw. That section of the base on which the headstock fitted was rectangular in shape, with a flat front, and bored to accept a large "inverted-cone" that allowed the headstock to be rotated or quickly detached. A pin, screwed in through the left-hand face of the casting, engaged against the cone, and drew the headstock down and locked it in place. Unfortunately there was no provision for aligning the headstock, other than fitting the tailstock ram with a centre and pushing it into the spindle hole - while simultaneously tightening the locking screw.
There were several serious oversights on this first model including a lack of provision to lock either the saddle or the cross slide to their respective bars and feed-screws with a 'right-hand" thread' - giving that annoyingly counterintuitive situation where turning a handle to the right produced a moment towards, instead of away from, the operator. One feature found on some early models (the writer's own example being so equipped) was a tiny oil hole drilled vertically through the front wall of the carriage by which means the end of the cross-feed screw, where it passed through the casting, could be lubricated. The smaller turned-parts on were probably made on a "Swiss Auto" - and ideal machine for making quantities of precision miniature components - with the plain-steel, 28-mm diameter handwheels having a pleasing diamond knurl around their outer edge, tiny micrometer dials engraved into the inner boss and straight pins for hand-grips. It is likely that more than one kind of handwheel was fitted on the production line, with some being of a slightly different diameter to others.
In comparison with later machines the drive pulleys exhibited several significant differences: they were thinner in section and of a much lighter, even delicate construction. Manufactured in fully-machined cast aluminium they had deep 'V' grooves and were mounted in the reverse direction and with the pair used on the motor and idler stud (at 49-mm), larger in diameter. The original belts were in the form of coiled-steel wire "springs", not an ideal material to run against aluminium. The motor bracket, later a neat die-cast affair, was a rather rough aluminium casting with only the holes machined. From the start of production the motor bracket came with an idler pulley - but machines have been found without this fitting (possibly to ease the fitting of a particular accessory) and hence only 6 instead of 11 speeds. A later offering was a "slow-speed" bracket with two idler pulleys designed to allow much lower revolution and so make more effective use of the "chase-type" screwcutting attachment.
Constructed as a one piece casting, the first tailstock had a distinctive spindle-retaining nut, just inboard of the handwheel, and a very pronounced rearward cantilever (to maximize the machine's limited between-centres' capacity). Because of its construction, and the fact that the bed bars were socketed into the base casting, it was necessary to dismantle the entire lathe if the tailstock had to be removed.
Instead of a taper, the 3/4-inch travel ram was fitted with a parallel socket and a external thread identical to that used on the headstock. An examination of the castings used on early lathes show them to have an inferior finish to later ones, though no doubt their material quality was entirely satisfactory. The vertical pillar was 24.5 mm in diameter, 240 mm long and with an installed length of 200 mm. The hand-grip used to convert the headstock into a drill was quite rounded, perhaps a little smaller than the latter cast-iron production version--but much more comfortable to use.
Made in Holland (by Motoren Eindhoven) the ball-bearing, 40 watts, 4000 r.p.m. brush motor resembled those used on contemporary sewing machines and was rated for intermittent use only. In order (no doubt) to give the unit a "machine-tool" or "technical" appearance it was finished, apart from the black-varnished field-lamination area, in an attractive crackle-black paint to match the lathe. To check if a motor has plain bearings look for a small hole in the (protruding) bearing housing at each end. The hole leads to a felt washer that wicks just oil, less any dirt, into the sintered-bronze bearings.
American machines all appear to have been delivered in a rather splendid fitted wooden box - while European customers, apart from those sold during the mid to late 1950s, had to be content with finest-quality cardboard. If you see a box for sale be aware that those for the very first models - the Mk. 1a at just over 12-inches long - were smaller than those for later machines. Most of the first boxes had nicely bevelled vertical corners, until at some point during SL1000 production , this was stopped, probably as an economy measure. Accessory boxes of the time were very distinctive with a turquoise (or teal) blue-and-white label with "Emco" spelled out in a diagonal line, a 'circle M' logo and "Made in Austria" printed underneath in small letters.
Having established the lathe in production Maier then set about both improving production methods (which necessitated changes to the machine's construction), and ironing out some of the design deficiencies that were becoming apparent as owners began to explore the limits of its potential.