BORING-MACHINES, WOOD. From the primitive auger to the high-speed multiple gong boring-machine of the present day is it far cry ; each year sees more advance either in the speed of work. in the quality of the work done, or in its range of dimensions and position, etc., until the catalogue of boring-machines alone would comprise quite a list, and a complete description of each kind made would fill a volume of no mean size. Suffice it if we select from a long list a few of the most typical or most ingenious and special for mere mention, in to the descriptions of construction and operation given in the former volumes of this Cvelmeedia. In sonic boring-machines the spindles are run by gearing. and in others by belting,. The latter permits higher speed of the sjandles and smoother running. For certain classes of long boring, as in wooden pump-tube work and the making of porch the cutter is carried on the end of a hollow pipe which has a worm rotating therein to carry out the chips; this being necessary in a horizontal machine, while a. vertical machine would he undesirable by reason of the great length of work required to be done. Even such a simple operation as boring holes for pins, as in sash and door work, is now performed by an attach ment to the double-arm sand-papering machine; the work being done by simply pressing the hand on the string, which drives the bit into the work, and on removing the hand the spring withdraws the bit from the hole, A very convenient machine for use in small shops, or where much large boring does not require to be done, is a portable boring-machine, Fig. 1, which is , entirely and may be fastened to P a post and belted directly from the line shaft.
There is a vertical spindle bearing the boring tool and driven by a mitre gear, inclosed in a box housing which carries the bar for starting and stopping, also a counterbalanced lever for bringing the auger to the work. The boring spindle passes through one of the mitre wheels, so that it may be raised and lowered while ro tating. A machine intended to meet the de mand for boring to the center of large pieces is built by C. B. Rogers & Co., and differs front the usual types of small single-spindle boring machines in having its spindle at a greater dis tance from the vertical post, so that holes may be bored in the center of the large piece. There is a stop-rod to regulate the depth of the hole bored, and also one to control the length of throw, thus doing away with the common ad justable collar of the spindle. The spindle is balanced. The table tilts for bevel work, and may be raised and lowered by a screw and hand wheel in front. The guide may be reversed to the front of the table. A cabinet-maker's bor ing-machine for two or three spindles, made by C. B. Rogers & Co., has a square column like
table east in one piece, and upon which there is a_plate which bears the front boring spindle lox, which, when they show two in number, are adjustable to and each other by a right and left hand-serew. Where there are three, the center lox is stationary and the others are adjusted to and from it by the screw and crank. The rear spindle-boxes have ar swiveling motion on the table to accommodate the changes in distance between the front boxes; and they are driven by an endless belt which, passing from the main driving pulley at the lower tort of the machMe, goes over one boring-spindle pulley, down under an idle pulley (which has vertical adjustment to take up the slack of the belt as it stretches), up over the other lor ing-bar pulley, and down under the main pulley. Thins both the spindles run in the same direetmon, and their adjustment practically makes no difference in the tightness of the belt. Eaelt of the mandrels to which the boring-bars are attached has a universal joint between it and the spindle. The table upon which the work is placed. and which bears a fence, is adjustable vertically in slides on the front of the machine, being controlled by a screw and hand-wheel. The table also has a horizontal movement to and from the bits. One very use ful of boring-machines, especially for ear-work, has three or mons vert kid spindles, each bearing a (1111'494ga-sized bit, and each having a conntwlalanced lever by which it may be drawn down to the work without much effort, and may he retired when the hand is tnken from the lover. In smelt umehines, there is little or no necessity for any lateral adjustment of the distance between the spindles, as only one is used at a time ; but an inilan'llInt feature is that the ones which hear the adjusting bits are driven at slower speeds than the others. Where they are for heavy work, the table upon which the lumber rests is furnished with four rollers. and in improved machines of this type the timber may be pushed along on the rollers by hand, if not very heavy, or the rollers may be operated by a hand-wheel in front of the machine, thus giving also a fine adjustment. The feed-rollers may also be turned by a fric tion-power attachment from the countershaft. The belt is best endless. passing over the main driving pulley below on a horizontal shaft, then up over a horizontal pulley on a line with the spindle pulleys and at right angles with the main pulley, then over one spindle pulley. making a quarter twist to get there, then back and forth over idle pulleys and the other spindle pulleys, and down over another guide pulley to the main pulley below.