Manufactured during the 1960s, the Hercus No. 1 tool and cutter grinder was the smallest of a range of such machines either made or factored by the Australian company. However, the No. 1 does appears to have been an indigenous design - and not a re-badged Clarkson, or similar.
Mounted on a rather slender cast-iron plinth cast integral with a stable, square foot, the machine had a centre height of 3.5" and admitted 15" between centres.
Included with a new machine was a range of equipment that allowed it to undertake external and internal cylindrical grinding, surface grinding and the sharpening of cylindrical cutters, saws, gear cutters, hobs, angle cutters, end mills slot drills, parallel and taper reamers etc. Items included: a No. 3 Morse taper universal workhead; tooth rest; a pair of work drivers; an internal grinding attachment; No. 1 Morse centres; a rough-turned 1.5" x 8 t.p.i. U.S.S. screwed chuck backplate; plain, dish and flared cup grinding wheels; drive belts and spanners.
Carried in double, spring-loaded high-precision ball races the spindle was of the oil-lubricated type and required no adjustment for the life of the bearings. Made from seasoned cast iron, the 5.25" x 24" two-part table was supported by ball bearings running on hardened steel ways and moved through its 12.5" of travel by sensitive rack-and-pinion gearing - control being possible from either front or rear with the usual pair of adjustable stops fitted in a T-slot running along the front edge. Connected by a central stud, the two parts of the table were locked together by clamps at each end with swivel control (for taper grinding) controlled by a screw adjustment at the right-hand side.
Carried on a sleeve that fitted over the centre column, the knee could be swung at right-angles to the spindle axis of the grinding wheel and was provided with clamps that provided an exceptionally solid lock. The 6" of vertical travel was controlled by a handwheel and screw thread with the micrometer dial reading in intervals of 0.001" - this being rather a coarse setting when surfacing grinding. Arranged so that the slides were always covered, the 4.5" travel cross slide had long ways with screw-feed control and another 0.001" graduated micrometer collar.
Totally enclosed and so proof against the ingress of grinding dust, the main motor was of 0.5 h.p. and the workhead 0.03 h.p. Convenient push-buttons were arranged on a plate fastened to the front of the main motor with the contactor switches protected inside the column.
The greatest distance from the wheel centre to table was 7.75"; the work-head centres could rise 1.75" above the centre of the grinding wheel and 4.25" below. Occupying a floor area of 38" x 32" x 53" the Hercus No. 3A weighed approximately 6.5 cwt.
Extra equipment listed included: 1.5" raiser blocks for the dead-centre work-heads; a 3.75" grinding wheel extension spindle; a gauge to judge the setting of centre height; a 3" swivel-base precision machine vice and a right-angle bracket to carry it (this allowed the vice to be swung to any angle in two planes); low centre holders with centres (useful such work as tap sharpening and grinding reamer flutes) and a collet attachment complete with a set of collets sized from 1/16" to ? in steps of 1/64".
If any reader has a Hercus tool & Cutter grinder, the writer would be interested to hear from you.
An owner writes: I was given my machine many years ago, it was going to be scrapped but appeared to be quite a nice job in regard to both design and construction. However, one drawback is that the motor is about the only thing that is sealed from dust ingress. On my example the slide that moves the table forwards and backwards has been worn by dust coming straight off the wheel - mine having a tatty piece of canvas between the column and the slide (they obviously had tried to protect the slide somewhat). The Slides for traversing from side to side do not have bearings as you describe having two V-slides( inverted Vs) like a lathe bed , so this must have been an alteration to the design at some point - again mine are badly worn.
The dovetail column seems to have survived well, I guess up and down movement is not used half as much as the other two. The wheelhead bearings were fine, but the little double V-pulley had seen better days.
As you mentioned, the slide-travel increments are coarsely graduated and have plans to use a different table on the knee to give some more head space. It would be great with a tall column and a new compound table and a vertical milling head (just dreaming ?)..