Early Rivett 8" Precision lathe.   
Was this beautifully-finished 8-inch Precision Lathe, as the makers proudly boasted in their literature, "The most complete tool of the kind ever conceived." ? Whilst even then that particular piece of hyperbole was probably taken with a pinch of salt the 8" Precision certainly came as close as was possible to this ideal using contemporary technology. It was a thoroughly well-thought-out design, made from the finest-quality materials and manufactured to a standard of fit and finish that even the passage of many decades cannot fail to disguise.
Edward Rivett had a long background in the watch tool industry before he turned his hand to manufacturing larger machines. From 1884 he was the General Manager of The Faneuil Watch Tool Company of Boston and expanded the factory's product range to include precision grinders and more profitable lines of larger bench lathes, including the No. 3 and No. 4. By the late 1890s he had designed, and was producing, the 8" Precision, which used the headstock and tailstock of the earlier No. 4 plain-turning precision bench lathe, but with a completely different bed 40-inches long, of cast-iron, milled and scraped finished on all sides. The distance between centres, was 22 inches and the swing 81/2" inches.
The unusual arrangement of having the smallest headstock pulley by the front bearing (instead of the other way round as is still common) meant that not only could the bearing could be much larger than normal for a lathe of the same centre height - but it was also surrounded by a greater mass of supporting metal.
Both spindle bearings had outer surfaces which were cylindrical in section - and could be continuously adjusted for wear whilst preserving their central alignment. The front bearing was 21/2" inches in diameter and both were 23/8"-long. Until about 1910, a now hard-to-find 4OS collet was used, later models employed the 4NS - and the last versions a 5C. 
The maker's description of the spindle and its bearings is worth considering: " ….. of the best tool steel, and like the spindles are made as hard as fire and mercury will make them, and then ground with diamond to a perfect fit." I suppose that says it all, really ……
If the headstock bearings were particularly well made, then the design and construction of the bed and carriage was even more impressive for, instead of sliding just on the top surface of the bed, and being located by keeper plates front and rear, on the Rivett 8" Precision almost the entire front face of the lathe bed was brought into play as part of the saddle-bearing surface to produce a bedding area of 74 square inches, a figure which it is believed has never since been surpassed on any lathe of comparable size Most lathes use only the top face, and upper edges of their beds to guide the saddle, but on the Rivett the front face of the bed, formed into dovetails and plain ways, was used to support the apron as well. This resulted in a very stiff structure beneath the cutting tool and a saddle-to-bed bearing area of 74 square inches (the rare English Spencer lathe had a similar but inferior system - and the little Toyo precision lathe of the 1960/70s rejoiced in twin aprons guided by both front and rear bed faces).
The lathe carried a maker's plate on the front of the apron that, fortunately, carried patent dates: May 17th 1887, November 10th 1891 and August 27 1895. However, these dates are not always a reliable indicator of production schedules and were often applied for some years before being granted: neither were they were they always strictly connected with the machine to which they were applied, often being used as a form of self-advertising - though in the case of Rivett's superb products  this would have been entirely justified. If any reader has an 8-inch Precision, or a variation of the lathe with different dates on the plate, the writer would be interested in hearing from them.
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The leadscrew, having been cut from, "one of the best master screws in the country.", was used only for generating threads, a separate power shaft being fitted to operate the power longitudinal and cross feeds. The power sliding, that is, along the bed, was operated through a "friction gear", able to be engaged and disengaged by a lever on the apron. A useful automatic disengage was also fitted to this feed, its trip stop being adjustable along the bed. Later 608s included a micrometer adjustment in the apron part of the stop, which allowed the machining of shoulders to within finely set limits.
An unusual extra, invented by Mr Rivett himself and which could only be fitted at the works for $50 before delivery of a lathe, was a device to compensate for temperature variations in the length of the leadscrew. No specific details of this compensatory mechanism are known.
As time passed the 8" Precision underwent numerous small changes; improved and enlarged micrometer collars, larger backgears of a different ratio, alterations to the leadscrew quadrant assembly, the option (never advertised) of a modified headstock casting with a single very wide flat-belt come pulley), the introduction of a screwcutting gearbox and changes in design to the apron and its power feed mechanism. The final version of the 8" Precision was the "608 Toolroom Lathe" - and it is this with model, and the watch-making lathes, that the name of Rivett is most closely associated today.
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Rivett 8" Precision fitted with a device catalogued as either the "Slide Rest and Milling Attachment" or "Cutter Milling and Gear Cutting Attachment" was a milling slide which included an indexing unit but was of a simpler construction than the "Spiral Attachment and Traverse Miller".
The cross feed travel was 4 inches and the vertical and angular movement 5 inches. Cutters up to a maximum diameter of 3 inches could be manufactured by the attachment, except ball cutters which could be generated in the range of 1/8 inch to 3 inches in diameter.
Index plates were supplied having 45, 56, 60, 64, 72, 80, 84 and 100 indents with others available to special order.
Rivett's advertising emphasised the pride they had in their lathes' ability to generate cutters and claimed that, even though they had milling machines of the very best kind in their workshops, nearly all their special angle cutters were made on either their No.4 or 8-inch precision lathes.
Also visible in this close up is the neat mechanism by which the screwcutting changewheels were driven. A gear, fitted to the left-hand inboard end of the headstock spindle, (and shrouded by the drive pulley) drove a gear and shaft which passed underneath the spindle bearing and emerged to drive a set of changewheels on the double-slotted quadrant arm. Later versions of the lathe offered the option of this mechanism including tumble reverse - but as space was very limited within the headstock belt-pulley, the gears were very small and prone to wear out both themselves and the larger gear that drove them.