Fig. 3231.
[Fig. 3231] represents a sand-papering machine, by P. Pryibil, in which a spindle has three stepped cones on one end, and a parallel roller or cylinder at the other. The steps on the spindle are covered with a rubber sleeve, and the sand paper is cut to a template, and the edges brought together and joined by gluing a strip of tough paper under them. When this has become dry the paper is slightly dampened everywhere except at the joint, and is then slipped on the taper drums. In drying it shrinks and becomes tight and smooth upon the rubber covering with which the drums are provided. These are of different sizes to fit different curves in the work.
Flat work is done upon the table, which is hinged and provided with an adjusting screw to regulate its height, and it can be raised to give access to the drum.
When sand paper is applied in this way, every grain is brought into contact with the work, whereas at first only the larger grains cut when it is used on the faces of revolving discs, as in some machines of this class. Furthermore, when used on drums it is offered ample opportunity to clear itself of dust; it therefore does not become clogged, and, as a consequence, it lasts longer and does more and better work than when used on discs.
Fig. 3232.
[Fig. 3232] represents a similar machine, but having a spindle vertical also, so that one face of the work can be laid on the table, which acts as a guide to keep the work square, the table surface being at a right angle to the vertical spindle.
The vertical cylinder or drum is split on one side, and provided with internal cones, so, that by screwing down the nut shown the drum can be expanded to tightly grip the sand paper, which is glued and put on as already described.