As far as can be ascertained, there were three surface grinding machines badged as "Pallas": a heavy but simple all-hand-operated one, the No. 0; the conventional fully powered No. 2 and the No.2Z, a very much more massive machine almost twice the weight of the No. 2 and with correspondingly greater capacity.Pictures below are high resolution and may take time to load
Pallas No. 0 Plain
Although the type has been made in other countries, it appears that the UK is home to more than its fair share of small, hand-operated surface grinders. Amongst those known are the Eagle, Capco, Superior, Herbert Junior and the tiny EXE.
All, even today, are useful machines: easy to set up and use they provide both the advantage of exercise -and disadvantage of lungfuls of metallic dust. So, if using one, rig up an extraction system - and use a good quality mask.
Introduced in 1954, the Pallas, was for its type, well specified and heavily built. The nickel-chrome steel spindle ran in precision, angular-contact ball races with spring-loaded compensation for expansion as they warmed in used. The table was unusual with in instead of a V and flat underneath - or running on anti-friction bearings.- on the Pallas is resembled a conventional V-edged lathe bed and was moved by a relatively small handwheel operating through a pulley and wire rope. The table top was also unconventional for the type of machine where, instead of the usual single T-slot down the centre, a T-slotted table was fitted - this able to be replaced by either a permanent or electrically operated 12" x 4" magnetic chuck.
On the competing models by Eagle, Capco and Superior, the grinding head was part of or bolted to the top of the main column, so ensuring absolute stability. However, the Pallas was arranged so that, like the popular American-made Brown and Sharp Series 2 models, the head moved up and down on square-sided ways, a handwheel with a large micrometer dial (graduated to read to 0.001" on the first machines made and 0.0005" on later examples) being used to activate the travel. To eliminated backlash in the drive, the head was counterbalanced by a weight hanging inside the column. The spindle, tapered at the end to take a grinding wheel mount, was driven directly by a flanged mounted 2800 r.p.m. 3-phase motor - rated at 1/3 h.p. on early models and 1/2 h.p. on later.
Unlike the Capco, which was available in various models, and the Eagle - built in Mk. 1, Mk. 2 and 534 Models - the Pallas No. 0 appears to have lasted a relatively short time, is very seldom encountered and was only ever offered in the single form shown below.
Pallas No. 2 Power-feed operated Surface Grinder
Was there ever a No. 1 Pallas surface grinding machine ? The writer has yet to find any evidence that there was - the next model in the range being the No. 2. Typical of its era with a mechanical table drive and looking not dissimilar in many respects to the Smart & Brown No. 2 Series models - and almost a dead copy of the "Robot" built in New York and also sold - or copied - in the UK as the Hoborough. Hence, the grinder worked, mechanically, exactly as would both the American machines:
to set the limits of 13.5" x 5" table's travel, adjustable dogs were carried in a T-slot that ran the full length of the table's front face. In operation, these caught against a plunger set in the forward part of the manual reversing lever - this plunger able to be withdrawn against a spring to allow, for whatever reason, table movementws to go beyond the reversing point but without disturbing the dogs. Set centrally on the saddle, the manual reversing lever was a useful facility when working on very short jobs, just flicking it left and right causing the table to oscillate as required. When operated by hand, one turn of the table's longitudinal handwheel produced a travel of approximately 2" - the wheel able to be disengaged against a spring-plunger for safety reasons when power drive was engaged. The table's longitudinal travel was a nominal 14 inches and the cross 5.75 inches.
More mechanical delight was to be found in the automatic traverse movement, the limits of its travel being controlled by stop dogs mounted in a T-slot on the saddle's right-hand face. A friction-type arrangement, the automatic cross-feed mechanism could be set to index the feed in, or out, at either or both ends of the table travel - the setting being achieved by two knurled-rim nuts set in partial-circle slots on the face of the unit. Feed rates from 0.01" to 0.09" were available, a large knurled-edge nut in the middle of the assembly being used to engage and disengage the drive; with the mechanism in the latter state the cross-feed could be manually operated without fear of the drive re-engaging. Driven by a 0.5 h.p. 3-phase motor, the 2,850 r.p.m. grinding head had a vertical travel of 7.25 inches with a maximum clearance beneath the wheel to the table of 7.25 inches - and to the T-slotted auxiliary table of 5.75 inches. The recommended grinding wheel was 6 inches in diameter and 1/2 inch wide. The Pallas 2Z weighed approximately 814 lbs.
Pallas No. 2Z
Built along the exactly same mechanical lines as the Pallas No. 2, the 2Z employed an identical form mechanical table drive the limits of which were controlled by stop dogs. With a working surface of 18.5 inches by 6.5 inches, the table had a longitudinal travel of 20 inches and across of 6.5 inches.
While the Pallas No. 2 had a grinding spindle running in three spring-loaded, angular-contact ball races, that on the 2Z was hardened and ground and turned in plain, adjustable bronze bushes. Driven by a 1.5 h.p., 1550 r.p.m. 3-phase motor, the spindle ran at 2,200 r.p.m, had a vertical travel of 9 inches and a maximum clearance beneath the 7-inch diameter by 1/2-inch wide wheel of 14 inches.
Also different to the No. 2, the drive system of the 2Z was contained within the cabinet base and of the conventional grinder type where a single continuous flat belt, guided by a pair of jockey pulleys passed up to the grinding head; as the head moved up and down, the belt was automatically tensioned by a weighed arm.
Very heavily built with an all-up weight of 1532 lbs, the maker's claimed that the main body of the machine on its own accounted for 72% of the machine's mass. Pictures of the 2Z's can be found below.