The knife-cleaning machine illustrated at Fig. 1 is a strong and serviceable article, and can be made without the aid of any expensive tools. Fig. 2 is an elevation of the machine. The baseboard A, the central upright B, and the crank C, which carries the handle Z), are made from 1-in. stuff, while the two wooden discs E and the uprights F, which carry the spindle G are of 3/4 -in. stuff. The pieces are in single thickness; but to prevent warping it is advisable to make the baseboard and the wooden discs of two thicknesses, with the grain crosswise, glued and screwed together. The baseboard having been planed up to 1 ft. x 7 in, the uprights p shou d be cut out; these are 3 in. wide where the spindle enters, increasing to 4 in. at the bottom with an extra 1 in. to be recessed in the base-board. The center of the spindle is to be 5 1/2 in. from the baseboard.
These uprights must be quite vertical and are secured to the baseboard with two screws each. The ho es o receive the brass tube bushes which form the bearings of the spindle are next marked out and bored. These holes should be perfectly in line with each other and should be made a driving fit for the tubular bushes, which must be nicely smoothed inside. The spindle G may be of brass or iron, 8 1/4 in. in length and about 3/4 in. in diameter. To this is fitted the two flanges H, (ceiling plates, as used in gas fitting, will answer very well); they should be a good fit on the spindle, as any looseness will cause the discs to which they are attached to run out of truth.
The wooden discs, 10 in. in diameter, should next be marked out with compasses and cut with a pad saw as close to the lines as possible, and afterwards smoothed round with a rasp or rough file. Turning them on the lathe, if one is available, would of course make a better job. From the center strike out circles slightly larger than the greatest diameter of the flanges and screw the latter on central. The holes to fit the spin-dle are continued through the discs, which are then mounted on the spindle to see if they run true. The disc to the right should push on and is held by a set screw.
The other disc is made a sliding fit, the fixing in this case being by means of a 1/4-in. headless screw, tapped into the spindle, working in a slot cut in the cylindrical part of the flange, shown in enlarged detail at Fig. 3. The disc can th n ue pulled away a short is-tance from the other to allow of the introduction of the cleaning medium. A strong spring M is colled round the spindle to keep the discs close together; a washer K being interposed between the spring and the upright. If the discs do not run true on the spindle a true line can be marked on the periphery by holding a pencil or a knife edge against it while the spindle is revolved, the surface then being planed true to the line. When true, the disc should be covered with hard felt, attached with glue.
The crank C, Figs. 1 and 2, which is 8 in. long by 1 1/2 in. wide, is bored at one end to fit tight on the spindle and at the other to take a 1/2-in. rod on which the handle D is fitted, the centers of the holes being 6 1/2 in. apart-The handle, a sectional view of which is given at Fig. 4, can be made from a piece of stout broom-handle, which should be lined with brass tube to fit over the 1/2 in. rod. At one end of the rod a rivet head is formed, then a washer is slipped on and then the handle.
The other end is forced into the hole in the crank. A 1/4-in. pin put through this and another through the spindle, securely holds the parts together. A washer is inserted between the crank and the upright to prevent them from rubbing together. Side play of the spindle is prevented in one direction by the crank of the handle, and in other directions by a piece of brass tube, similar to the spindle bushes, cut the correct length, and slipped on the spindle i, Fig. 2, when putting the machines together.
The central upright B, Figs 1 and 2, which is 2 in. wide, is next fitted to just clear the discs, the thickness being reduced to 1/2 in. after it leaves the base-board. See Fig. 1. The opening in the upper part is 1x2 in., the top edge being level with the center of the spindle. The knife to be cleaned is passed through this opening between the discs.
Screw holes for clamping-down purposes are made to suit the table or bench on which the machine is to be used; when fixed, the edge of the baseboard should be flush with the edge of this table, so as to allow of the proper working of the handle.-"Work," London.