Jig Boring Machines & Techniques Jig Boring Training
Used by the B. Elliott Machinery Group, the Excel name indicated items of better-than-average quality and usually directed towards a specialised segment of the market; it was adopted by various of the Elliott brands, including Victoria, Cardiff, Progress and Invicta to market lathes, millers, small jig borers, die milling machines, precision filing & sawing machines, tool & cutter and surface grinders and other machine tools from the 1930s until the 1960s, .
A straightforward copy of the American Liney Jig borer, the standard Excel No. 1 used, like all others of its kind, a fixed compound table and relied for all vertical movements on a quill-feed head that ran up and down on ways machined into the inner face of a heavy, cast-iron column. The head, of massive proportions for its capacity, was counterbalanced by a weight hanging from a roller chain and wire inside the column. The only way of moving the head assembly through its 8 inches of travel was by hand, there being no rack or gear feed; however, with great ingenuity, instead of the original American designers allowing the weight to balance just the head they also arranged for the chain to lift in the middle of a flat bar that connected to both the head casting and the quill - so counterbalancing the latter and helping to reducing backlash (a similar mechanism being employed on one of the smaller Swiss SIP jig borers). Another, very rare version of the Excel has been found with the top section of the main column arranged to swivel on a massive boss; this arrangement, while adding to the machine's versatility, unfortunately precluded incorporating the head balancing mechanism. The writer has only encountered two examples of this model and, if you have one, he would be delighted to hear from you
A 0.5 h.p. 1425 rpm motor was generally fitted, this being fastened on a plate at the back of the column to drive forwards by "A" section V-belts via a ball-bearing supported and adjustable intermediate pulley to the main head - the system giving a useful range of eight speeds: 225, 350, 475, 740, 1000, 1700, 2000 and 3400 rpm. The drive was enclosed by a front-hinged guard, stayed by a two-part tie bar, that neatly and safely covered all three pulleys and both belts.
With a quill travel of 3-inches, the distance from its centre to the column ways (the throat) was 5.75-inches. The spindle assembly - beautifully made in nickel-chrome steel - was heat treated, ground all over, lapped on its bearing surfaces and help in high-precision bearings that were claimed to need no adjustment in service and which were provided with fifty pounds of pre-load pressure. To obtain perfect concentricity the outer diameter of the quill and the spindle nose were finish ground while running in their own bearings - and to prevent the spindle suffering interference from pull by the drive belt, its pulley (mirroring the arrangement used on many high-class lathes) ran on an independent set of ball races.
Collets were held in the quill by a compression nut on the nose - and could be had in sizes from 1/8" to 1/2" in increments of 1/32". Unfortunately, these collets were of the ordinary split-from-one-end type and so limited the machine's usefulness as a light-duty vertical miller - any sideways forces on the cutter causing them to work loose unless only the most judicious of cuts was taken. In recognition of the fact that so tempting a small machine would (unless locked in a strong room) be pressed into service as a milling machine, the Linley company went on to equip their version with Schaublin Type ESX collets which, being split from both ends had a vastly-superior gripping ability. In a similar vein the much later British Downham/Elliott version of the could be had quipped with an alternative collet set into which milling cutters could be screwed. If you have one of these machines and wish to mill check the collets page to see if any company can help. Early models used collets as the Brown & Sharpe 00 or 00A, catalogue numbers 4996 and 5071.