Radial chair-boring machines have two spindles working at the same time and arranged to be set at different distances. The work is fed in on a table sliding on ways parallel to the bits. Some machines have adjust able table and fence and quick-return spindles. Some have more than two spindles, and in some of these the distance between spindles may be regu lated with but little trouble; in some, too, the angle at which the bits will bore is adjustable.
In vertical-spindle machines the spindle may be very readily counter balanced, so that the work need not be moved to the bit, but merely placed in position. The vertical universal borer has a table with vertical adjust ment, and also angular adjustment in a plane including the spindle-axis. A three-spindle vertical auger machine has for each spindle separate adjust ment across the stick, and for each one, also, its own counterbalance and handle. The table has a series of geared rollers, arranged to run in either direction, moving the timber end-wise either way. One belt from the counter-shaft carries power to all three spindles.
Some makes of horizontal machines have vertical adjustment for the table, which may also be tilted at any angle to the anger-spindle, to per mit of boring at any desired upward or downward angle. The boring spindle is thrust forward by a counterbalanced treadle. For very large work in hard wood the spindle is moved by a screw and a hand-wheel. The gang boring-machine makes a large number of holes at one operation without the necessity of laying them out. The boring-spindles run in frames gibbed to a connection gateway and vertically adjusted by a screw to each. In one type there lies under the frame and at right angles to all the spindles a long drum, and a continuous belt runs on this and on all the spindle-pulleys, the last belt-fold running the length of the machine between two pulleys having axes parallel to those of the spindles. This does away with the necessity of an idler for every spindle. The radial car-borer has a horizontal auger in a frame having motion in a hori zontal circular arc of 9o°. The bit has lengthwise movement and the table vertical adjustment. One form of horizontal car-boring machine has a horizontal auger-spindle running in a frame at right angles to the column which carries it, but parallel with the face of the column. This
bit is mounted in a frame, which has considerable vertical adjustment upon the face of the column. It also has horizontal lengthwise traverse. The sill or other piece to be bored runs upon a number of friction-rolls, which have their axes parallel to the axis of the spindle. The spindle and its frame are raised and lowered by power. The same machine, with an ar rangement by which the boring-apparatus may be pivoted to a plate which allows it to swing to any desired angle in either direction, makes a radial horizontal ear-boring machine. For car-work a three-spindle horizontal auger machine is very useful, each spindle having its own vertical adjust ment by power, so that each one may bear a different-sized auger from the others and any one may be used as desired. The table has rollers for the timber, and also a fluted roller and hand-wheel for moving the stock quickly to a determined point. Each bit is brought forward by its own handle when desired.
IMO/plc increase to the utmost extent the capacity of a drilling-machine it is frequently fitted with several drills and spindles, which can be worked at the same time. In the small horizon tal four-spindle drilling-machine, represented in Figure IS (ii/. 24), the rota tion is imparted to the articles only, while the drills are fed on in a recti linear direction; hence this machine may be considered a lathe with four spindles. In either case it represents an important principle for applied mechanics—namely, that of The mulfifilicalion of Mc fool, whereby the total expense for frame, moving apparatus, etc., for each separate tool can be con siderably decreased.
Comb/Ha/ion small shops where a great variety of work is required, while the quantity is not sufficient to warrant one machine for each operation, machines are built which can be rapidly and effectually changed from one class of work to another. Putting bor ing-bits and matching-heads on the end of saw-arbors, changing planing heads to moulding-bits, and the like class of substitutions, constitute one grade of possible variations in work; but some machines permit of two different operations being performed on opposite sides at the same time, each side working independently.