Designed for use by instrument, optical, watch and clock-making repair shops and in experimental and development workshops today the little Pultra cylindrical grinder is a rarely-encountered machine but, like the similar (though more heavily built) Jones and Shipman versions, is a highly sought-after addition to the machine shop of any truly ambitious model or experimental engineer.
On cylindrical grinders, in order to grind very small diameters to a high degree of accuracy, the surface speed needs to be very high. To achieve this the workpiece spins in one direction and the grinding wheel, often powered by a separate motor, in the other. With a little ingenuity this type of grinder can also be adapted to other tasks and an examination of the pictures below will show the machine set up for grinding between dead centres, a method also used for many years on horological and precision bench lathes.
The Pultra could take a maximum length and diameter between centres of 5.5 and 2 inches respectively and run a 5-inch by 0.75-inch wide grinding wheel at up to 4400 r.p.m.  The slides were all provided with pressure oil nipples, for positive lubrication, and the longitudinal slide had a maximum stroke of 3.5 inches. The feed micrometer dial wheel was 4 inches in diameter with 250 divisions - 10 revolutions moving the slide 1/4 " towards stone (1 div =0,00254 mm)
On the Pultra a cast-iron table at the rear with a single longitudinal T-slot was used to carry the grinding head and motor assembly (the arrangement allowed the head to be positioned anywhere along the length of a workpiece) whilst the bed, headstock and drive motor were formed as part of a compound slide immediately in front of it. The headstock, whose spindle ran in ball races and took WW-20 collets, was arranged to carry a simple bracket on which was mounted the drive motor. With no power feed fitted to either traverse the operator was required to move the table left and right with a small handwheel connected to rack-and-pinion gearing and make the necessary in-feed by the use of a very fine-pitch screw fitted with a large-diameter micrometer dial. For grinding tapers and awkward shapes the bed could be swung on its mounting and, in addition, the head assembly rotated in its housing. To minimise vibration the grinder was mounted on a heavy, purpose-built stand with built-in coolant and electrical controls - three separate push-button switches for the head, grinding wheel and coolant motors and a reversing switch. 
Though the machine appears to have used no standard Pultra parts, the headstock, with its overhung drive pulley, bore a strong family resemblance to that employed on the 17/50 and 17/70 lathes.
There were two other Pultra grinders, a radius type and one of unknown type.