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Probably the most common "serious" add-on for any lathe is a milling slide - this accessory providing a travel either just vertically or, on models with a swivel on the both the horizontal and vertical axis, at any chosen angle. A wide variety of types have been offered with some, like one version of the later Myford model, having a double swivel with a two clamp bolts on each axis that added much-needed rigidity; others, for example the sophisticated Boxford type, had only a swivel on its vertical axis but could mount, for work holding purposes, either a vice or, more usefully, a small T-slotted table (and, in addition, a very expensive dividing attachment.) A special model, intended to carry a high-speed milling and grinding spindle - and oddly not equipped to do otherwise - was the English Potts, this being a vertical column type and available with base fittings that allowed it to be mounted on the majority of model engineering lathe of the time. Some slides on watchmakers' lathes and of the Bench Precision type (as made by such as Stark, Ames, and Schaublin) were also intended for this purpose, the drive coming from an "overhead", a special countershaft fitted above the lathe with its pulleys arranged to give very high r.p.m. A rather special example of this type - and a very fine one - can be found on a superb American-built lathe of unknown origin, the "Unknown41"
The Chicago Tool & Engineering Co. of 8365 South Chicago Avenue, Chicago were in business from around 1918 making a variety of machine-tool fittings - vices and rotary tables included - with their market most definitely directed, in early years, towards the Amateur and casual user of machine tools rather than professional, amongst the more printable comments about their products being: "Palmgren showed the Chinese how to make pure crap for the hobbyist". So, possibly not something that one would find taking pride of place in a toolroom then...
Designed to be as simple as possible to mount, the claw-like foot of the Palmgren milling slide was just slipped over the toolpost stud and bolted in place. If the lathe had a T-slotted cross slide - though this was a fitting very rarely found on US lathes, but common on small lathes made in the United Kingdom - the unit could be secured by a T-nut and stud. Three sizes were offered, these having jaw opening widths of 1/1/2 , 2 1/2 and 4-inches with the vise forming the whole of the slideway and the only means of securing a job - the largest version being over twice the price of the smallest and intended for much bigger lathes. All types have been found with a number of different right-angle mounting brackets, these being supplied to fit most popular lathes including models by South Bend, Logan, Clausing, Delta/Rockwell and Sheldon: what might be described as the "standard" type used a simple slotted (fork-like) base for clamping down, with the slide arranged to pivot around a boss locked by a single through bolt; another mounting took the form of a forked foot with the slide clamped by two bolts passing through a pair of curved slots. Yet another had a base with a curved slot that allowed around 30 degrees of swivel each side of central and, through the vertical face, a single bolt for swivel that was backed up - for use when set vertically - by two additional bolts with each passing through its own (curved) slot. When the slide needed to inclined either side of central, one bolt had to be removed, leaving just one to aid clamping. A micrometer dial was fitted as standard to the feed screw, with many users finding it far too small - although because the dial did not obstruct the slide's travel, this was longer than would otherwise have been possible.
Do milling slides work? They do, but all suffer from several intractable problems including being able to see what is happening (you'll notice the illustration below shows an operator posing for the photograph - but unable to see the cutter working…) However, when fitted with a high-speed spindle for milling or grinding they are perfectly acceptable, though when holding work to be machined by an end mill or slot drill held in the chuck of a lathe the spindle speeds available are rarely high-enough for effective use with small diameter cutters. Rigidity can also be a problem and the Palmgren, with its vice constructed as an integral part of the slide, had a particular drawback - if the vice handle was wound up really tightly the whole slide was distorted sufficiently to make it stick or even jamb. However, if patience is exercised - and just very light cuts taken - most jobs can be completed successfully. The lesson? If you can afford a vertical milling machine and have room for one, life is very much easier.
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