SANDPAPERING MACHINE'S. Sandpapering machinery, with which may be included finishing machines using sanding belts, and sanding cylinders and cones, arc of great variety, according to the class of work which they are to perform. The function of all is the same : to remove roughness and produce a smoothly finished surface. Their action is often supplemented by polishing attachments, which put upon the wood a luster, and give it a smooth, velvety feel which mere sandpaper or its equivalent could not impart.
The sand-belt machine shown in Fig. 1 is for polishing the body of wagon and carriage spokes, and also for finishing neck yokes, single trees, handles, and similar articles. There are two sand-belt pulleys, having parallel horizontal axes, the dis tance between which may be regu lated by hand wheels and screws ; the article to be polished is held between centers supported by radial parallel arms, swinging on an axis parallel with those of the belt pulleys. One of these centers may be turned by a hand crank, so as to present every side of the piece in succession ; the other is a (lead-center.
Another type is known as the bracket machine, being designed to attach to a wall or post. There is a bracket bearing a vertical pulley spindle, and a hinged arm, the outer end of which has a vertical spindle, on the lower end of which there is a drum covered with sandpaper upon its lower head. The rotation of the sandpaper drum, and the traverse of the hinged arm in every direction in a horizontal plane, enable the machine to cover the entire surface of a door, or similar plane piece, and at the same time do work that is reasonably free from scratches. The sandpaper disk is vertically adjustable to different thicknesses of stock, and has a spring handle to regulate the pressure on the surface, and a suction fan to carry away the dust. Another form of this machine has, instead of a bracket, a column placed near a cast-iron table, upon which the door or other piece is placed, and the hinged arm has more joints. In the column is placed the exhaust fan.
Another machine has a single vertical spindle, bearing a plain cylindrical drum or tube of small diameter, covered with sandpaper on its convex surface, and is useful for finishing the internal and external curves of scroll-sawed work. The spindle in the best of such machines moves automatically up and down by a crank and pitman, as it rotates, so as to free the surface of the work from scores. A development of this type has two such spindles, placed about :; ft. apart, and one bearing a large and the other a small cylinder or tube. these working in curves of either large or small radius. In these, each spindle has a verti cal reciprocating as well as a rotary tnovement ; the former being produced by cranks at each end of a shaft, running across the frame at the bottom of the spindles.
A triple-drum sandpapering machine, shown in Fig. 2, is for sandpapering planed sur faces for furniture, pianos. etc., where the work is to be varnished or painted. There are three drums. made of steel, on which the sandpaper is placed, its grade being according to the work to be done. The first drum carries coarse paper, the second a fine grade for smoothing, and the third a finer grade for polishing. Each of these drums has lateral oscil lation across the material, to prevent the formation of lengthwise scores, which would be the case if the material moved straight, and the rolls had no such endwise vibration. The feed rolls are eight in number, four above and four below the platen, and are driven by a train of expansion gearing, They are so placed that the material will pass between the upper and lower sets, and open to receive material 8 in. thick. The lower rollers are placed one each side of the drum, each roller being in a separate bed-plate, which is adjustable with the roller, and the roller has a separate adjustment Cram the bed-plate. Each bed plate can be set to gauge the amount of cut to each drum, or all the bed-plates can be set in line, and the drums set to the cut desired above this line. The upper rollers are mounted in a frame over the corresponding lower rollers. The pressure rolls are three in number, one over each arm, to hold the material firmly to them, and are separately adjustable by hand wheels in front, which operate worms and worm gears.
There has been produced one machine which will joint and sandpaper the meeting rails of sash. The sash is placed on a movable carriage, with the meeting rail resting against ad justable stops. by which a heavy or a light eat may be obtained, as desired. The sash while passing through the machine is held in position by springs, by which means the meeting rails are worked to the same thickness. The jointing is done by a rotation cutter head on the 7ertical axes of one side of the machine, and the sandpapering head or drum is borne by a horizontal shaft, which springs its working surface practically in line with that of the cutter heads. The capacity for jointing and sanding is eighty windows per hour. There is a plow ing and boring attachment, the sash being placed against a gauge on the lower table, at an angle of about 30', and the stile bored with one bit to receive the cord, The sash is then placed against a gauge on the upper table, and grooved or plowed to the hole, so that the cord can be heavily knotted and slipped into the hole, and the weight of the sash will draw the knot to the bottom.
Sand Wheel : see Ore-dressing Machinery.