Fox of Derby: Lathe in Birmingham
Note: This is a sub-section of Fox of Derby
See photographs. This is described as 'c.1820', and it came from an 1817 machine shop at Milford Mill, Derbyshire.
It is now in store in the Birmingham Museums and Art Gallery Collections Centre, having been removed from the former Birmingham Science Museum.
W Steeds' 'A History of Machine Tools 1700 - 1910' includes photographs and information on the lathe. It is larger than the lathe at Wortley Top Forge, having a much longer bed, but the design is very similar, except for the lack of a leadscrew for screwcutting.
The lathe was 'officially' dated at 1817, although Steeds was 'inclined to put it five to ten years later'. The lathe also features in L. T. C. Rolt's 'Tools for the Job', and it is interesting to note that, like the Wortley lathe and the Birmingham museum planer and London Science Museum's slotter, it came from Strutt's ground-breaking workshop at Milford Mill. Rolt says: '… they were used in the construction and maintenance of textile machinery. They were driven by waterwheel and as the date 1817 appears on the cast-iron beams and line-shafting brackets of the building that was evidently built to house them, it is reasonable to ascribe them to this year. The machines have been attributed to William Strutt, but while Strutt was a most ingenious engineer and was undoubtedly responsible for the Milford building, the advanced and masterly design of the tools clearly reveals the hand of Fox'.
The acheivement of James Fox in identifying key aspects of lathe design, which we now take for granted, cannot be overstated. His appreciation of the the important design criteria and the quality of his detail design and the quality of construction are remarkable for the time.
Details
In photo 3, the ratchet handle and small wheel (bottom left) were connected to a small chain which moved the drive belt between the fast and loose pulleys on the overhead lineshaft, in order to start and stop the lathe. A great deal of effort went into making the cast iron bracket for this lever, and bedding it to the shape of the lathe's bed and leg. The bracket is also visible in photo 13. The horizontal rod at the bottom of photo 3 moves a lever to operate the reversing bevel gear cluster seen in photo 4. The bevel gears turn the square layshaft which drive the worm and wheel to move the lathe's carriage.
In photo 6, the two brackets projecting from the headstock are used to support the shaft with six pulleys and two gears seen in photo 7. The two gears slide on 'feathers' (long keys which are a sliding fit in the gears). One pair or the other will be engaged to provide high or low ratios, giving 12 spindle speeds.
Photo 8 shows the carriage (saddle) and toolpost, and the large wormwheel which turns a pinion engaging with the cast iron rack to traverse the carriage. An important feature of the carriage is the extent to which the 'wings' extend forward, providing excellent support when the toolpost is close up to the headstock (the slideways for the carriage extend all the way to the end of the bed). Also note the cut-outs near the ends of the 'wings'. These were provided to accommodate a plate, enabling to carriage to be used as a boring table.
Photo 9: The worm travels with the carriage. To disengage to drive from the carriage, the large lever seen in photo 8 throws the wheel forward out of engagement. Alternatively the square layshaft can be stopped or reversed by the bevel gear cluster at the headstock end.
Photo 10: The design flair and the fine workmanship are evident in every detail of the toolpost.
Photo 12: The design of the tailstock is generally well thought out. It can be moved along the bed by a hand-cranked pinion. Provision is made for offsetting the centre for taper turning. The only shortcoming is that the barrel can only be moved forward by the forcing screw, and has to be pushed back after releasing the screw.
Photo 13 shows the steps taken to ensure that the cast iron bed was rigid, without incurring excessive weight.
Photo 16: Fine work by the blacksmith: the square part of the layshaft was forged and filed, not machined.