Stark No. 4 Precision Bench Lathe
Stark Tool Company – Waltham, Massachusetts
By Dan Eyring, Volunteer
The exhibit displays an example of the No. 4 Stark Precision Bench Lathe, put into production circa 1900. This early version of the No. 4 lathe includes a small table set up for use as a horizontal milling machine complete with a swivel dividing head and tailstock - with the cutter carried on an extension of the headstock spindle. The bevel-gear operated elevation control is a particularly compact and well-executed design.
The lathe is mounted on the manufacturer's superb iron-framed oak cabinet stand with self-contained drive system. The countershaft inside the stand carries three wide pulleys of different diameters with each driving up to its own fast-and-loose pulley on the overhead countershaft. The right-hand outer pulley within the stand provides a fast speed range, the outer left-hand pulley a slow range. The central pulley, mid-way in size between the outer pair, are arranged to provide a reverse drive - by the traditional means of putting a 180-degree twist in the belt. Any of the drives can be instantly engaged and disengaged by treading on one of three pedals which were connected, by wires, to the belt-shifting forks on the overhead countershaft.
Besides the lathe spindle, the countershaft also powers - via a 2:1 flat-belt pulley system at its right-hand end - a parallel shaft designed to provide a high-speed drive to milling cutter and grinding attachments held in the lathe's tool post.
As was the case for all early model Stark lathes, the lathe design is based on a bed with beveled edges and a single central T slot that located the headstock, tailstock and fittings such as a compound slide rest. However, at the heart of the lathe's accuracy was a superbly-made, high-speed headstock spindle and bearing assembly based on a design already standardized for watch maker lathes, wherein a hardened, ground and lapped spindle runs in glass-hard steel bearings - a system which represented the very best use of the materials and manufacturing techniques available in the late 1800s.
The spindle and bearings were originally advertised as being manufactured from "English steel" - almost certainly a reference to crucible steel. The headstock design continued unchanged until the late 1920s when the option of precision ball bearing spindles was offered, at first to special order - and then only recommended by the makers for applications where very high speeds had to be sustained for long periods.
Stark's claim to be to be the originator of the precision bench lathe was bold and unequivocal (and printed on all their sales catalogs), with the first examples being built by John Stark personally in 1862, well before any of his competitors - who were also mostly from the Waltham area. The company was also famous for their watchmaker's lathes and also built a wide range of specialized machinery and tools for use in watch and clock-manufacturing and repair plants.
Although the Stark Tool Co. has now disappeared the American tradition of very high quality precision plain-turning lathes is continued into the 21st century by both the Derbyshire and Levin companies.
[Source - http://www.lathes.co.uk/stark/]
If you would like to learn more about the fundamentals of lathes and the different kinds of lathes, please follow some of the links bellow:
What is a lathe?
What are the parts of a lathe?
What kinds of lathes are there?
What are the origins of the lathe?