BLOCK MACHINERY. 



611 



islDck Ma- winch handle at Y. When turned, it advances the 

 ^ dunery, U pp cr B lid e r with its screw, the tool, and all the ap- 

 ~~~^~ paratus towards .' e sheave, fixed at the end of the 

 mandrel. The screw of d has a pulley H placed on 

 the end of it, but fitted to slip round, and e is an arm, 

 fitted on the end of the screw, to slide to and from the 

 pulley, but made with a fillet, so that it must always 

 turn round with the screw. The central piece of the 

 arm e has a groove round it, which is embraced by 

 an opening in the middle of a lever J\ exactly the 

 same as the lever in the mortising machine. One end 

 of this lever is jointed to the solid piece F, and this 

 is its fulcrum ; the opposite end, markedyi is jointed 

 to a rod g, suspended in an iron loop h, fixed at its 

 upper end to the holder for the tool a. By moving 

 the rod g endwise, the arm e slides upon its spindle, 

 and, when pushed towards the wheel H, intercepts a 

 stub projecting from the wheel, which is always turn- 

 ing, and now carries the screw with it ; but when the 

 arm is pulled away from the wheel, the connection is 

 destroyed, and the pulley slips round on its spindle, 

 which is the end of the screw. The wheel H is turn- 

 ed round by means of an endless band passing round 

 a pulley k on the end of a spindle, carrying the 

 wheel I, which is turned by an endless screw up- 

 on the mandrel at I. The band passes over the pulley 

 k, then makes a turn round H, and goes to a pulley 

 K, from which it returns to k. The pulley K is si- 

 tuated at the end of a spring M, fixed to a pillar of 

 the frame. The elasticity of this spring is such as 

 to cause a sufficient tension of the band to turn the 

 wheel round, and the direction of the band allows 

 the position of the pulley H to be altered, by turning 

 the screw Y, without loosening or tightening it. N 

 is a rest, similar to that used in a common lathe, fas- 

 tened by a screw passing down through the frame. 

 The workman takes a sheave, and fixes it against the 

 chuck at the end of the the mandrel B, fastening it 

 tight by the screw in the centre ; then by pressing 

 the strap X sidewise, it passes on the pulley D, and 

 puts the mandrel in motion. The screw Y is now 

 turned, till the tool at a advances so as just to cut 

 the coak of the revolving sheave, (we suppose the 

 screw of the slider d has betn previously withdrawn, 

 by turning back the handle O, so as to bring the tool 

 nearly into the centre of the sheave). The workman 

 now pushes the rod g towards the pulley H : this, 

 as before described, puts the screw in motion, and 

 moves the slider d, with the tool, away from the cen- 

 ter of the sheave, turning it all the way across to a 

 true flat surface. When the tool arrives at the out- 

 side of the sheave, the loop h, which moves at the 

 same time, intercepts a nut n, screwed on the end of 

 the rod g, and by this means draws the rod, relieving 

 the arm e from the pulley H, so that the motion can- 

 not be continued to break or damage the screw or 

 sliiers. During the time the tool was traversing the 

 face of the sheave, the attendant, having nothing else 

 to do, was employed in turning the groove in the 

 edge of a sheave, by a gouge placed on the rest N. 

 The lathe is now stopped, by shifting the strap X 

 upon the loose pulley E. The sheave is removed from 

 its chuck, and turned with the other side towards it. 

 Then the handle Y is turned back, to draw the tool a 

 clear away from the sheave, and the handle O is turn- 



ed back to bring the tool again to the center. The Block Ma- 

 lathe is now set in motion, and the operation above de- chiuery. 

 scribed repeated, except that the groove on the edge *-"""V~ rf 

 does not require to be turned a second time. In our 

 drawing, we have not been able to explain a most inge- 

 nious contrivance in the pulley, which gives motion to 

 the endless strap turning the lathe. It is found bv 

 experience, that a certain velocity is best for turning- 

 brass or other soft metals to the greatest advantage, or 

 of cutting the greatest quantity without wearing the 

 tool, but that wood will work best with a much great- 

 er velocity. The sheave contains both the metal coak 

 and the wood sheave ; and to give it the proper ve- 

 locity for both, is the object of the contrivance in 

 question. It is effected, by having two pulleys, or 

 wheels, which give motion to the endless strap X. 

 These are of equal size, and placed close together, 

 their axis being in a line. One revolves with the 

 velocity proper for turning brass, and the other 

 for wood. Now in the commencement of the ope- 

 ration, when the tool works upon the coak only, 

 the strap works upon the slowest of these two 

 pullies ; but as the tool advances, and has got over 

 the metal, and begins to cut the wood, the strap is 

 shifted to the quick pulley, and turns the lathe with 

 an increased velocity. The tool a is merely an angu- 

 lar point j but the slider d is so perfectly true and 

 firm, that it cuts as even a surface as could be expec- 

 ted from a wider tool, and with this advantage, that 

 the point will cut through every thing it meets with 

 less danger of breaking than an edge. The tool is 

 fitted into a holder, and held by the screw b, by 

 loosening which it can be removed to make way for a 

 sharp one. The lathe adapts itself readily for differ- 

 ent sized sheaves. The chuck may be unscrewed 

 from the end of the mandrel, and another put on. 

 The screw Y will allow of any thickness ; the nut n, 

 on the end of the rod g, can be screwed along the 

 rod, to adjust the diameter of the sheave ; and the 

 rest N can be drawn out in the same manner as any 

 common lathe. 



The machinesjbr making the pins. As we are not Machines- 

 able to present our readers with drawings of these for making 

 machines, we have but little more to say of them the pins, 

 than was mentioned in our list of the machines. The 

 iron pins are forged between swages, by two men, 

 in the usual way, being cylinders, except a small 

 length at the end, which is left square for the pur- 

 pose of holding in one of the cheeks of the block, to 

 prevent the pin from turning round. These pins being 

 centered by a simple tool, are carried to a lathe of 

 immense strength. It has a short mandrel, and a 

 back centre to support the extreme end of the pin. 

 It has also a long slider fixed parallel to the pin, and 

 provided with a rod similar to g in the last machine, 

 which detaches the movement of the screw, when 

 the whole length of the pin is turned. The holder 

 of the tool has a small table fixed to it, which carries 

 a vessel containing cold water, and provided with a 

 cock, from which a continued stream of this water 

 falls upon the tool. This is an essential provision, 

 as the great strain of turning so large a piece of iron 

 would certainly heat and soften the tool, which is of 

 an excellent form for the purpose, being a cylindrical 

 piece of steel cut obliquely, so as to form an elliptic 



