Early Milling Machines

The Wikipedia entry for Milling (machining) is recommended as a good source on the history of the development of milling machines. There is no point in duplicating the information presented, so this entry will be limited to some lesser-known aspects of the milling of metals.

A milling process had been in use from the 17th century to machine gears for clocks and watches.

It is likely that milling, or at least flycutting, would have been undertaken on ordinary lathes prior to the introduction of purpose-built milling machines.

The earliest milling machines made in the USA in the early 19thC were very similar to lathes, with the workpiece being movable in the X and Y planes.

Various claims have been made about 'interchangeable manufacture' and the associated use of milling machines in the second decade of the 19th century. However, the production of accurate work with a satisfactory finish is far from straightforward. Considerable demands are imposed on the rigidity of the machines and on the quality, detail design and method of holding the cutters. To address and overcome these challenges in the early part of the 20th century would have been an impressive achievement. It is easier to envisage milling being used for roughing out components, using semi-skilled labour, leaving the finishing to be done by filing. However, John H. Hall designed a breech-loading rifle in 1811 and went on to supervise production of this rifle at Harpers Ferry Armory. It is stated that he devised and built milling machines with guides and stops such that truly interchangeable parts were produced on machines operated by boys. Hall's ideas spread to Springfield Armory and the private armouries. When Simeon North began building Hall rifles in Connecticut, the Hall's gauging system ensured that parts were interchangeable between rifles from the two armories.. Discussions of 'interchangeable manufacture' rarely go into the all-important question of as-machined tolerances, or about which specific components could be used straight from the machine, and which items needed to be individually dressed to satisfy the gauging requirements.

The challenges of machine rigidity and the limitations of cutter design, manufacture and retention may have been addressed by simplicity: by having individual machines designed to do one specific job with one type of cutter and with the minimum number of moving parts (to reduce the scope for chatter due to looseness and lack of rigidity). An early example of such a machine was included in the Marc Brunel/Henry Maudslay blockmaking machinery at Portsmouth. The machinery included a form of vertical milling machine built in 1803, although it machined lignum vitae rather than metal. It was by no means a versatile machine, having only one purpose, namely the milling of recesses in sheaves.

An early example of a versatile milling machine with third axis (vertical) movement was that introduced by Gay, Silver and Co in the USA c.1841. It also featured overarm support for the spindle.

Another early type of versatile milling machine with Y-axis movement came to be known as the 'Lincoln Miller'. It resembled a lathe, but with a simple arrangement for elevating the spindle by raising each of the two headstock bearings by screws. Various names have been associated with its development: Thomas Warner, Frederick W. Howe, Elisha Root, and Francis A. Pratt.. The first examples were made at the Phoenix Iron Works, Hartford of George S. Lincoln and Co in the early to mid 1850s.. The arrangement for elevating the bearings was inconvenient, and it seems likely to impair the rigidity of the machine, and hence its acccuracy, productivity, and and ability to produce a good finish. Nevertheless, Lincoln millers were produced in vast numbers and remained in production for decades. On some, an outboard bearing was added, corresponding to the tailstock of a lathe.

The next type of milling machine from the Phoenix Iron Works was the Lincoln Index milling machine, also designed by Pratt and built by Whitney. The spindle bearings were fixed in the headstock (i.e. non-elevating). The headstock could be moved relative to the workpiece in the X and Y planes. The workpiece was held in a vice or other fixture on top of a vertical cylindrical column which could be elevated (Y plane movement). The column could also be rotated, and was supplied with an indexing (division) plate. Starting in 1861, numerous examples were supplied to the armoury of Samuel Colt.

The Lincoln machines were not particularly versatile, but the introduction of 'universal' milling machines in the early 1860s would revolutionise aspects of engineering production. The most prominent early universal machines came from Brown and Sharpe of Providence, RI. In addition to machining flat surfaces, grooves, etc., they were available with accessories to allow the machining of gears, twist drills, splines, etc.

A barrier to the acceptance of milling machines would have been the quality, availability, expense and ability to sharpen the milling cutters. These aspects were addressed with great success by Brown & Sharpe.

A further problem area concerns the method of holding the cutters, especially end mills, so that they run truly and are held securely.

Some British Developments

James Nasmyth wrote about a machine he built c.1830, while working for Henry Maudslay, to mill the faces of small hexagon nuts. He developed self-acting industrial versions of the machine and was selling them in the late by 1837. Writing to a customer in 1838, he advised that the cutter should never exceed 55 rpm to avoid damaging the cutter. By 1839 Nasmyth, Gaskell and Co had sold over 50 machines.

Richard Roberts produced self-acting machines on a commercial basis to machine hexagonal and other multi-faceted components, and these were sometimes described as 'polygon machines'. They were made by firms in which Roberts was involved, namely Sharp, Roberts and Co (early 1840s), Sharp Brothers and Co (early 1850s): see Directory of Manchester and Salford, 1853. p33-37, Roberts and Dobinson (early 1850s).

Kendall and Gent made a nut and bolt head cutting machine with three milling heads, allowing rapid production using cheap labout.

Richard Roberts was undertaking milling on a larger scale by 1839, when American visitor William C. Davol described Roberts's ' Cutting Engine for cutting locomotive Engine cranks, the cutter was made by having a cast Iron wheel about 18 inches in Diameter 3 1/2 to 4 In wide with cavitys cut in the edge about 3 In deep to 5/8 wide set 3 In apart round the face of the wheel to receive the steel cutters which was ruther wider than the wheel and ground sharp on three sides. '

A number of British firms produced machines for cutting keyways and slots for cotters using rotating cutters. These were commonly called slot drilling machines. Nasmyth, Gaskell and Co started making such machines c.1853, calling them 'patent grooving machines', although they were not patented by Nasmyth. Sharp, Stewart and Co started making such machines in the mid 1850s to Sharp and Furnival's patent of 1855. An accurate large scale model from c.1857 is/was on display at the Musee des Arts et Metiers in Paris. The Science Museum have a sample workpiece produced on one of these machines. Photo here.

Another Manchester maker was J. and J. Kershaw. Their 'Drilling & Recessing Machine' was described and illustrated in The Engineer in 1856. It was a small vertical 2-axis milling machine, limited to cutting keyways in shafts.

These slot drilling machines were effectively vertical milling machines, but their makers did not develop these or other milling machines to increase their versatility, unlike the situation in the USA, where universal milling machines were developed.

See Also

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