Fig. 224.
Fig. 224B.
At a later page is described a slide rest with the arrangements of the tool-holder somewhat improved, and calculated for the reception of larger tools and apparatus. The little rest here described is, however, very light and useful.
[Hoblyn's Compound Slide-Rest.]
A compound spherical slide-rest, for ornamental turning lathes, which has been patented by Mr. Hoblyn, Rickling-green, Essex, is capable of turning and ornamenting accurately spheres and any segments of circles convex or concave, either on the surface or cylinder; also, it is stated that by the addition of templates any other curves, not segments of circles, can be turned out, in addition to the work performed by an ordinary compound slide-rest. In our illustrations, [Fig. 1] is a side view, and [Fig. 2], an elevation of the rest. A is the lower, and B the top plate, C the carriage, and the saddle as usual. The lower plate, of iron, is planed on bottom and sides, and has a longitudinal bevelled slot in the bottom to receive the fastening bolt, so that the plate can be tightened up at any point on the lathe bed. At one end of this bottom plate is a piece raised the whole of its breadth, accurately turned and faced, with a stout turned pin, b, for a pivot in the centre. A wheel, c, is placed around this raised piece, having any specified number of cogs, and on its top any specified number of small holes drilled to receive two pins as segment stops. The top plate is slightly narrower than the bottom one, and has on its underside a corresponding surface to that raised on the plate A, turned and faced with countersunk hole in the centre to fit on the pivot b, on which it is tightened by a screw and washer. The top of B is placed to receive two parallel bars of brass, bevelled on the inner edge, so as to form sliding bars for the carriage C, one bar being a fixture, the other capable of adjustment by tightening screws. The sides are also accurately planed, and on one a tangent screw, e, is so fixed as to be put in and out of gear with the brass wheel, c, for the purpose of driving the top plate round the pivot b. In the raised surface of B, is a countersunk slot forming a quarter circle, with screw passing through it into the bottom plate; by this means the top plate can be firmly fixed at any angle to the bottom plate for the purpose of slide-rest turning. A small pointer, f, works clear of the brass wheel in the capacity of segment stop—two small pins being placed in the specified number of holes in c. On the opposite side of the screw, e, on the top surface, a screw, g, works in two standards screwed into the plate through slots in the bar, which works through a traveller, h, firmly attached to the carriage, C, and therefore capable of driving the carriage in a rectilinear direction—for slide-rest purposes. This carriage, C, consists of an iron plate i, with standard k, top plate l, with parallel brass bars to receive tool receptacle m, the bottom plate and standard being in one piece with the plate, planed side and bottom, so as to slide truly between the parallel bar on B. The standard has its surface accurately turned with a pin in centre to form pivot. The top plate is planed true, bottom, sides, and top, and has a countersunk hole in the exact centre, so as to work on the pin, and tightens up with a large nut. In the plate is a countersunk slot forming a quarter-circle, with screw passing through into the standard, to set the tool receptacle either parallel with B for spherical turning, at right angles to B for slide turning, or at any angle for thick and thin cuts, and similar patterns when used either as a spherical or slide rest. The parallel bars are to be similar to those on B, to enable the tool receptacle to be advanced or retired by screw or lever. This part of the machine can be adjusted for height of centre thus:—The standard k to be a hollow cylinder with fixing screw on one side; the plate i to be made with turned pin on bottom, to fit into standard; elevating screw; saddle as usual, but with the addition of a small hole drilled in one of the sides, and a corresponding one in the side of the lower plate A, so placed that when a pin is fixed into these holes the pivot is exactly central to the lathe centre.
Fig. 1.