Chap. XIII.
TOOLS AND MACHINES.
1031
and spring fall. Two ironstandards passing from a pitin the floor of the manu-factory support a table atany required height, on whichthe iron work to be drilledis laid ; the drill is insertedin a socket at the bottom ofthe shaft, where it is securedby a bolt.
The portable Hand Drill isa similar machine, and foundvery convenient for a va-riety of purposes, particularlywhere the work to be drilledis difficult to move. A framesupports the upright spindlewhich carries the drill; onthe top is a screw, by whichit can be raised, and the re-volving motion is given bytwo small bevel wheels placedat right angles with eachother; these are turned bya small fly-wheel, to the rimof which is affixed a handlefor working it; at the sametime, a slight revolving mo-tion is given to the upperhandle, which causes the drillto descend.
The Foot Drill differs onlyin the mode by which theupright drilling spindle risesand falls; the examples al-ready given are self-acting;on this it is performed bythe pressure of the foot.
Machines for boring or upright drilling were some years ago much employed in the pre-paration of timber water pipes. In the work by Belidor before alluded to, the tree to bebored is mounted upon a truck or wheel carriage, and well secured in its place: a water-wheel gives motion to a vertical spindle, which by means of a trundle and face-wheel movesround a horizontal bar that carries at one end the auger, by which the boring is effected:as this revolves, motion is given to another wheel, around the shaft of which is attached arope that draws the carriage forward on which the tree is placed, as fast as the borer cutsits way : when the whole is cut through, the carriage is drawn back, and the process isrepeated with a larger auger, and so on, until the whole is of a sufficient diameter.
In some machines the tree was made to revolve, and the cutter was fixed : the tree wasin a vertical position, and in other instances the core was cut out whole; this was per-formed by employing a hollow’ cylinder, armed at the extremity w’ith a circular saw’, of thetrepanning form, the cylinder being made to rotate as the saw cuts its way : the coreentered the hollow of the cylinder as the latter advanced, and was thus preserved. Stonepipes were so cut that the block of stone was set nearly upright, and in the centre of theintended pipe a block of wood was fixed, with a hole drilled in the middle to receive thepivot of a perpendicular axis or spindle, considerably larger than the intended pipe, and ofa triangular or square form; this revolving, performed, by means of the cutter w’hich wasattached to its end, the centre operation.
The horizontal boring Machine used for metal cylinders consists of a piece of iron calleda cutter-bead, which slides upon an axis, and has the knives or steelings which perform theboring fixed into it. The cylinder to be bored is firmly secured upon a frame prepared toreceive it, and the cutters are advanced by means of a hollow’ cast-iron tube, on each sideof which is a longitudinal groove or aperture : the cutter-head consists of two parts, viz.a tube fitted upon the axis with the greatest accuracy, and a cast-iron ring fixed upon fourwedges; on its circumference are eight notches, into which the cutters or steelings are heldby wedges ; the slider or catst-iron ring is prevented from slipping round by two short ironbars put through the axis, and passing into notches cut in the ends of the sliders. The
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