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 



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. 



