NEW ROCK-BORING MACHINE.

Westport Times, Volume II, Issue 238, 6 May 1868, Page 3

NEW ROCK-BORING MACHINE.

A professional gentleman, present on the occasion, supplies to the Bendigo Advertiser this interesting description of the new rock-borer:— A trial was made on Thursday, at Messrs Vivian and Co's foundry Castlemaiue, of Mr E. G. Eord's patent rockboring machine, in the presence of twenty or thirty of the principal persons interested in mining affairs in Castlemaine and Sandhurst, and some of the engineers connected with the department of the Victorian Water Supply. The machine itself is a cylinder about 30 inches in length over all and 4-o- inches in diameter, having a screw bar to fix the front end against its work, upon which screw the arrangement for the machine to move itself forward when at work is fixed, viz., a brass nut with notches on it. The screw bar is fixed three or four inches off the side of the cylinder, and projects one foot nine inches beyond the front end of it. The machine is self-acting in every movement. An ordinary sized drill is us°d, made in the usual way, only with not quite so keen a cutting edge, and is made round at the but to fit into the nut. The piston is moved in the cylinder much on the same principle as a steam hammer, only that compressed air is used instead of steam. On this occasion the pressure varied from 80 lb to 43 lb on the square inch. We should state that the arrangement for this trial was only made in a very temporary manner; a round boiler, 30x40 feet diameter, which happened to be lying in the shop, being converted for the time into an air receiver. The air receiver could only be filled with compressed air before the trial commenced, as the air pump could not be worked while the machine was being worked, because the same piece was used (which contained some water to keep the air cool) to force air into the boiler as was used to drive the machine; hence the difference of pressure after working two hours—the air being continually expended from the receiver without any being pumped in. The valve motion of the machine is a new and beautiful idea, and works well — it is difficult to describe it without diagrams. The motion for turning the drill as it works is also a very pretty piece of mechanism, and is quite original ; it works admirably. The stones upon which the machine was tried were necessarily not very large, as they had to be carted to the foundry; they consisted of a piece of Milestone and a piece of granite, perhaps together weighing about a ton. These stones had to be bolted, and wedged up to the machine, and were not thoroughly fixed, so that at first starting the stone moved a little and jammed the drill in the hole; but after the first half hour of working the stones became settled, so this jamming did not occur again. The first hole tried was put in five inches in about one minute; the second, third, and fourth holes were in the block of granite, right through the block, 12 inches in thickness, in five minutes i <?., 36 inches in 15 minutes (not counting the time of changing the drills.) The next two holes were put in ten inches, each into the bluestone, at the rate of one minute and a half for each hole for actual boring time. The last three holes were put in the bluestone with one drill; equal to a depth of thirty inches in four minutes and a half actual boring time ; the holes were all about one inch and a quarter in diameter. The reason that the holes were not put deeper than ten inches was because no longer drills had been provided; there is no difficulty in putting holes in to any depth with this machine. The time taken up in changing the drills would be about five minutes, but when men get accustomed to their work, much less. Mr. Christopherson, the chief engineer of the department of Victorian Water »' upply, was present for a short time, and expressed himself highly pleased with the performance of the machine ; but it is a pity that pressure of business necessitated his hurrying away to Melbourne, as he would" have been much more pleased with the manner in which the machine worked after the stones had been properly bedded. "We think this invention is likely to make an entire change in the system now adopted by most of the mining companies, who have to sink or drive far in the hard rock.

[BEtfDIGO ADYERTISEB, APRIL B.] As Beveral inquiries have been made about Nr R Or. Ford's patent rockboring machine since we published a short report of the trial of it at Messrs "Vivian and Co's foundry at Castlemaine on Thursday last, we now give our readers a few more particulars, for which we are indebted to the same gentleman who gave us the first account. The weight of the machine itself is 120

lbs, and the method of fixing it in a shaft or drive would be determined according to circumstances. Thus, in sinking a shaft or in a small drive, a piece of timber 9 inches square and long enough to reach across the shaft, with a screw at one end to tighten it across the shaft or drive, is all that would be required, upon which the machine can be fixed to bore at any angle. But in a large and long tunnel, it would bo worth while, probably, to have the machine fitted on to a lorry with one cast iron column, or two, if two machines were required. The method of conveying the air pressure to the machine from the airreeeivor on the surface would be by means of a 1 inch ordinary gas piping, to within 30 or 40 feet of the work, when a half-inch flexible hose must be used, in order to adjust the machine to its work, and remove it while blasts are discharged. Three-horse-power of any ordinary engine is sufficient to pump the air to drive one machine. The calculation from the only date which we have at present shows the cost per foot of putting in holes into granite is about one-half of the cost by hand labor. Irrespective of the saving in money, where time is an object in sinking or driving the machine would be very beneficially used, as we think it saves 75 per cent in time over hand labor.