400 



BLOCK MANUFACTURE 



centre-pin in a direction exactly perpendicular to tho surface resting against the three 

 screws ; the other, at E, perforates tho holes for tho commencement of tho sheave 

 holes. Both borers are constructed in nearly tho same manner ; they are screwed 

 upon tho ends of small mandrels, mounted in frames similar to a lathe. These frames, 

 o and H, are fitted with sliders upon the angular edges of the flat broad bars, I and x. 

 The former of those is screwed fast to tho frame ; the latter is fixed upon a frame of 

 its own, moving on tho centre-screws at L L, beneath the principal frame of the ma- 

 chine. By this means the borer B can be moved within certain limits, so as to bore 

 holes in different positions. These limits are determined by two screws, one of which 

 is seen at a ; tho other being on the opposite side, is invisible. They are tapped 

 through fixed pieces projecting up from tho frame. A projecting piece of metal from 

 the underside of the slider K of the borer E, stops against tho ends of these screws, 

 to limit tho excursion of the borer. The frames for both borers are brought up to- 

 wards the block by means of levers M and N. These are centred on a pin, at the op- 

 posite sides of the frame of the machine, and have oblong grooves through them, 

 which receive screw-pins, fixed into the frames o and 11, beneath the pulleys P P, which 

 give motion to the spindles. 



5. The mortising -machine is a beautiful piece of mechanism, but too complicated for 

 description within the limits prescribed to this article. 



6. The corner saw, Jig. 141, consists of a mandrel mounted in a frame A, and carrying 

 a circular saw, L, upon the extreme end of it. This mandrel and its frame being 

 exactly similar to those at G and H, Jig. 140, do not require a separate view, although 

 they are hidden behind the saw, except the end of the screw, marked A. This frame 

 is screwed down upon the frame B B of tho machine, which is supported upon four 

 columns, c c, D D, is an inclined bench, or a kind of trough, in which a block is laid, 

 as at E, being supported on its edge by the plane c c of this bench, and its end kept 

 up to its position by the other part of the bench D D. 



By sliding the block along this bench, it is applied to the saw, which cuts off its 

 angles, as is evident from the figure, and prepares it for the shaping engine. All tho 

 four angles are cut off in succession, by applying its different sides to the trough or 

 bench. In the figure, two of them are drawn as being cut, and tho third is just marked 

 by the saw. This machine is readily adapted to different sizes of blocks, by the simple 

 expedient of laying pieces of wood of different thickness against the plane D D, so as to 



fill it up, and keep the block nearer to 

 or farther from the saw ; for all the 

 blocks are required to be cut at the 

 same angle, though, of course, a 

 larger piece is to be cut from largo 

 than from small blocks. The block 

 reduced to the state of E is now taken 

 to 



7. The shaping-machine. A great 

 deal of the apparent complication of 

 this figure arises from the iron cage 

 which is provided to defend the work- 

 men, lest tho blocks, which are re- 

 volving in tho circles or chuck with an 

 immense velocity, should bo loosened 

 by the action of the tool, and fly out 

 by their centrifugal force. Without 

 this provision, the consequences of 

 such an accident would be dreadful, 

 as the blocks would bo projected in 

 all directions, with an inconceivable 

 force. 



8. The scoring-engine receives two 

 blocks as they come from the shaping- 

 engine, and forms the groove round 

 the longest diameters for the reception 

 of their ropes or straps, as represented 

 in the two snatch blocks and double 

 block, under Jigs. 140, 141. 



A, B, Jig. 142, represent the above 

 two blocks, each held between two 

 small pillars a (tho other pillar is hid behind the block), fixed in a strong platen, and 

 pressed against the pillars by a screw b, which acts on a clamp d. Over tho blocks a 

 pair of circular planes or cutters, E E, are situated, both being fixed on the same. 



