Page:Popular Science Monthly Volume 90.djvu/790

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774

��Popular Science Monthly

��A Bali-Bearing Lathe Center for Large Holes

WHILE working with a lathe it is often necessary to turn objects in which the hole is larger than a solid lathe center,

���Dimensioned parts for a ball-bearing lathe center of larger than usual proportions

such as pulleys, bushings and pipes. Refer- ring to the drawing, A consists of one solid piece, being provided with a ball-bearing channel or race; B indicates the revolving swivel which bears the other half of the bearing channel. To fill the race there will be required twenty-three ^-in. steel balls. The extension is fitted with a bronze bush- ing C, and Z) is a knurled nut for holding the bushing C in place. The adjusting nut E holds the swivel B against the balls, thereby providing an extremely close run- ning fit. In operation, heavy grease should be packed between the parts A and B for lubrication. — Lee S. Fletcher.

��An Easy Method of Making Banana Liquid

TO make the so-called banana liquid, put I lb. of gun cotton into i gal. of acetone, and to the solution add 2 gal. each of amyl acetate and petroleum benzine. Add the amyl acetate first, then dissolve 20 oz. of gun cotton in 2 gal. of amyl acetate, and add 2 gal. of 90 per cent coal tar benzole or solvent naphtha. As these liquids are very inflammable, care must be exercised to keep the solution away from fire.

��Holder for Cutting Glass and Photographic Plates

THE increased use of lantern slides as well as of plates for the vest pocket cameras calls for a size not easily obtainable in the various kinds. Where a particular make of plate is desired and cannot be had in the proper size, the convenient method of cutting glass for lantern slides and plates for vest pocket cameras, from the more common size plates as illustrated, may be appreciated. This arrangement may be used in the dark-room for cutting unexposed plates. It consists of a board 15 in. long by 12 in. wide for the base and a built-up edge on three sides with i-in. strips ^ in. thick. A gage is made of a piece of wood 10 in. long, 33/5 in- wide and ^ in. thick to fit snugly between the raised pieces on the sides. It is necessary to have the gage adjust itself automatically, and for this reason its width must be the same as the required plates, allowance being made for the width of the axle support on the glass-cutter. This measurement is usually about 3^ in., but will vary some- what on different makes of cutters.

The best method is to measure the cutter accurately by placing the gage along a fine line drawn with a pencil on a white card and making a line parallel to this with the wheel of the cutter. The distance between these lines is allowed on the gage. The upper surface of the base is covered with a piece of baize to prevent slipping. In use place the plate gelatin-side down, with its end against the raised end and the gage in position over it. As the gage or glass cannot slip, an accurate cut is the

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��A gage-board for cutting unexposed photo- graphic plates accurately in a dark-room

result. If the plate required is rectangular, then it is necessary to have a gage for the length as well as for the width.

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