email: tony@lathes.co.uk
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Toyo-Sakai ML1 Precision Lathe
Also sold as the "Spindle Star"

Toyo ML1 Continued Here

An Instruction Books & Drive belts
are available for the ML1

Toyo Home Page   ML210 Milling Head   Toyo ML2




Designed and developed during the 1950s by Mr. Sakai, owner of the Japanese Sakai Special Camera Mfg. Co. Ltd., the original Toyo was not intended  as a commercial proposition but to help with production of his large-format box cameras. However, so successful did the lathe prove (and, with so few machine tools of the type available in Japan at the time) it found a ready home market followed by strong overseas sales - where the competitive price undercut machines of similar quality from Germany (for example, by Lorch and Boley Leinen) and in America (Levin and Derbyshire). In germany the lathe was marketed by the Forkardt-Gefitec Company, from Dusseldorf, and badged as the "Spindle Star"
Of delightfully simple construction, yet cleverly-engineered, the precision ML1 was 590 mm long, 260 mm wide, 175 mm high and weighed around 15 kg. With a 50 mm centre height and a capacity between centres of 250 mm the lathe was ideal for watch, clock and instrument work and was unusual for its time in having (like the late-model Boley F1 lathes of a similar size) a tightly integrated drive system. While the Boley was based on established watchmaker's design, and fitted with specialist equipment for turning and boring pivots, Toyo used a drive system very similar to that on the 1954 Emco "Unimat" with a rear-mounted 100/240V 50/60 HZ 145W motor (with neat, built-in switch-gear) set to drive the spindle directly or via a speed-reducing intermediate pulley. The result was a range consisting of a single slow speed of 250 r.p.m. and three high of 1000, 2000 and 3000 r.p.m. Running on precision ball races the hardened and ground spindle was bored through to clear 12 mm and carried an unusual  size of Morse taper in the nose - a 1.5. The spindle end was formed not with a thread, but a blank end, tapped to take chucks and other fittings secured by bolts passing through their bodies. This arrangement provided perfect precision and security when run in reverse, but meant a time-consuming job to change fittings. For holding collets a simple type of compression collet holder was offered (with a screw-on nose) that took standard dead-length collets in metric-only sizes with bores of : 2, 2.5, 3, 4, 5, 6, 8 and 10 mm.
Continued below:

The clean lines of the precision Toyo ML1

Continued:
Of great interest was the arrangement of the bed and carriage: the bed, carried on a cast-iron under-plate, was machined with "vertical" square-section ways on the front and rear faces and formed the support for a carriage with aprons at both front and rear - a design that was, for its size, unique. As confirmation of the suitability of this arrangement the superb, hand-built Rolls-Royce precision lathe of 1948 used an almost identical arrangement. Because the headstock could be rotated on the bed, only a two-T-slot cross slide was fitted - there being, at first, no offer of a top slide unit, just a simple block toolpost taking 8 mm deep tools being provided. However, with the advent of the useful little ML210 lathe the slide from this was offered as an option under Part Number 3017. Although the cross slide travel, at 65 mm, was very reasonable, the makers neglected to use the old trick of increasing this (and thus making it more useful when a milling slide was fitted) by the simple expedient of using a cantilevered feed-screw support bracket instead of the simple flat-plate type fitted. One revolution of the handwheel advanced the slide 1.5 mm.
Unlike most contemporary precision lathes of its size and type (which tended to use just a simple, watch-lathe type bolt-on compound slide assembly with a long-travel top slide) the ML1 was able to drive its saddle along the bed. Not only could this be done with a graduated handwheel at the tailstock end of the bed (the travel was 250 mm) but also under power, through a train of gears connected to a leadscrew that ran down the centre line of the bed. However, in this respect it was not alone, the tiny American ManSon hobby lathe of the 1940s managed the same feat on an even smaller scale. With the leadscrew passing down the centre of the bed the carriage attachment point was arranged to be directly under the toolpost, so ensuring as near a straight-line pull as possible - rather in the manner of, amongst others, the toolroom-class Boley L Series lathes
Available as an optional-extra, the changewheel set was mounted inside an enclosure carried by the outer face of the leadscrew's dog-clutch assembly. Although the gear were able to generate a useful range of pitches - 0.25, 0.3, 0.35, 0.4, 0.5, 0.6, 0.7, 0.75, 0,8, 0.9, 1.0, 1.25 and 1.5 mm - the relatively high bottom speed of 250 r.p.m. made screwcutting rather an awkward proposition. However, in mitigation, it must be said that the surface finish of the very small diameter threads likely to be generated would have benefited from such revolutions. The gears could also be arranged in various compound settings to give different rates of fine sliding feed and their housing ensured that no lubricant was splashed onto the drive belts or contaminating the operator's hands as he changed speeds.
Of conventional design - but with guidance ways at both front and rear - the No. 1 Morse taper tailstock had a 38-mm travel barrel with its handwheel engraved (or most likely rolled) with a micrometer scale graduated at intervals of 0.025 mm. One turn of the handwheel advanced the barrel 1.5 mm.
Over a long production run only minor changes were made to the ML1, one of which was the use of parallel instead of taper-face micrometer dials and the use of a chrome rather than natural finish. Another version of the ML1 was also made, the ML2. Fitted with a 250 mm diameter faceplate, and having three speeds of 100, 300 and 500 r.p.m., this was intended for large-diameter facing work but sales must have been few and the model is rare - most clock, watch and instrument makers already having larger lathes in their workshop.
Despite being a genuine precision lathe, with a number of advanced and ingenious features, models of all years  were finished in an unfortunate choice of paint - a cheap-looking green "Hammerite" - that would have been more at home coating one of the early, casually-assembled and badly-made Taiwanese lathes made for the amateur market in the early 1970s.
A friend of the writer's bought a new ML1 in the early 1970s and, after changing the micrometer dials for a set of larger, finely-engraved and chemically blackened units, spent many years turning out tiny experimental jobs under sub-contract to Rolls Royce..

Arrangement of the motor-drive system and the outrigger plate carrying the carriage-feed gear train

Toyo ML1 headstock showing both the belt-drive and changewheel covers in place and the ball-ended dog-clutch operating lever used to engage the carriage feed




Toyo ML1 Bed-support plate and bed assembly

Underneath the cross-slide showing the generous proportions of the cross-feed screw and bronze nut

Like all Toyo lathes the non-zeroing micrometer dials left something to be desired with cruder-than-expected engraving of the 0.025 mm interval scales

The layout of the bed ways is clearly shown in this picture of the tailstock
and carriage handwheel assembly


Toyo-Sakai ML1 Precision Lathe Continued Here

Toyo Home Page   ML210 Milling Head   Toyo ML2

An Instruction Books & Drive belts  are available for the ML1

Toyo-Sakai ML1 Precision Lathe
Also sold as the "Spindle Star"
email: tony@lathes.co.uk
Home   Machine Tool Archive   Machine-tools Sale & Wanted
Machine Tool Manuals   Catalogues   Belts   Books  Accessories