Typical of the specialist machine tools manufactured by Sloan & Chace was their Automatic Pinion and Small Spur Gear Cutting Machine. This cleverly-designed and beautifully constructed piece of machinery was used to produce, one at a time, small gears up to an inch in diameter for use in pocket watches, clocks, typewriters and other mechanical devices. After a suitable gear blank had been fixed in position it was automatically indexed through the required number of steps while a rotating cutter generated the tooth form. For light work, or where the quality needed was not so high, a single cutter was used to form the complete tooth profile but, if a lot of material had to be removed (or very precise gears manufactured) special versions of the machine could be ordered that mounted either two or three cutters on the spindle. Each cutter was ground so as to remove more metal than the one preceding it and each was automatically moved forwards into the position after the one before had finished its job.  The mechanism was arranged so that each cutter could be individually adjusted to compensate for inevitable reduction in diameter that occurred as it wore in service, or after being reground to correct its tooth form. However, the makers advised that, "In actual practice, a two-cutter machine (having one roughing cutter and one finishing cutter) has been found equal to the most exacting requirements." The machine stood on a hollow cast-iron box that held the all-important coolant supply that was pumped over the cutter and workpiece before draining back,  through filters, into the sump. The spindles and their bearings followed traditional watch-lathe design being conical in form  and manufactured from the finest quality, hardened and ground steel. The work-holding and high-speed spindles were carried on dovetail slides that could be: "delicately adjusted by stop screws".
A special wall-mounted round-rope (gut-drive) countershaft was provided that ran at 700 rpm; this drove the cutter spindle at 1700 rpm and the worm shaft (by which means the automatic indexing and other movements were generated) at 1200 rpm. The machine weighed 123 lbs.
A much later Bechler pinion cutter can be seen working here. Although a more complex device, with a number of advanced features, the principle of operation is identical to that employed by the Sloan & Chace.

Sloan & Chace Automatic Gear Cutter No. 1. Designed with the same ingenuity and built to the same high standards as the company's Automatic Pinion and Small Spur Gear Cutter this slightly larger (though still very compact)  miniature machine tool was intended for the economical production of: "gears of light pitch up to 3.5" in diameter in stacks up to 2" long." The machine was arranged with two horizontal spindles, both mounted on V-slide ways, at right angles to each other; one spindle carried a rotating cutter whilst the other, on a horizontal slide, held a set of gear blanks on its nose and could be made to move forwards and backwards over a range of up to 2.5 inches. Both spindles and  their adjustable conical bearings were made from hardened and ground steel with the drive to the cutter spindle by a single 1.5-inch diameter flat pulley from a remote countershaft. At the end of each cut  the dovetail slide carrying the cutter spindle was caused to rise slightly (to prevent marking by lifting the cutter clear of the job) and, as the work-holding slide moved backwards on its return stroke, the partly-finished gear was indexed round by a worm-and-wheel driven crank working through a pawl carried on an adjustable swinging arm. Cut depth could be adjusted by hardened stop screws fitted with micrometer dials reading to 0.001".
The makers claimed that seven-eights of the machine's time was spend in actual work and only one-eighth in returning and indexing and, as it  worked entirely automatically and stopped after the final tooth was cut, high rates of production could be maintained with one operator able to look after several machines simultaneously.
The picture shows the machine with its protective cast-iron swarf cover removed; this guard was fitted with a hinged access door to allow work to be removed and replaced with a minimum loss of time. In addition to the standard machine a version adapted for spiral gear cutting could be made to special order.

One of a range of similar machines offered by the company for the economical, small-batch production of light gears in any material including steel, the Sloan & Chace No. 3 Fully Automatic Gear Cutter was based on the design of a simple horizontal miller . The machine boasted table and indexing movements all positively driven by gears with the main driving mechanism enclosed within the knee and lubricated by an oil-bath. The table's fine fed  was by a screw thread travelling through a fixed bronze nut and its rapid return provided by a separate belt drive to a pulley low down at the back of the main column. The indexing mechanism was protected from swarf by cast-iron covers and arranged to start and finish slowly (to prevent "overthrowing") - it being activated by a crank turning a pawl carried on a adjustable swinging arm. The crank could be adjusted to give any throw to a maximum of one-sixth of a circle - though the makers claimed that by increasing the width of the cam on the index trip an index of one-half circle could be obtained.
The cutter spindle ran in adjustable tapered bronze bearings and both it and the work-holding spindle were (to allow the use of readily-available milling machine arbors) supplied as standard with the then ubiquitous Brown & Sharp No. 10 taper. The machine could be driven by either existing overhead line shafting or by the maker's own fast-and-loose countershaft unit with 3-inch wide pulleys at a recommended speed of 160 rpm. 3 spindle speeds were available and three rates of table feed: 0.001", 0.002" and 0.003" per revolution of the spindle. The machine weighed 1325 lbs.

A specialised machine of a type also built by several competing companies (prominently Stark, Waltham and Rivett) all of whom had close connections with the mass-production  watch-making trade, the Automatic Staff and Pivot Lathe was intended for the rapid and accurate manufacture of the "staffs" and "pivots" used extensively in watch and clock mechanisms.
Should you have a similar machine - or any other unusual Sloan & Chace machines - the writer would be interested to hear from you.