WIRE. 



wire confills in drawing the piece of metal tlirough a hole 

 in a plate of Heel, by which means the metal is rendered of 

 an equal fize, and cither round or of any other figure cor- 

 refponding with the figure of the hole in the draw-plate ; 

 the metal is thus reduced in fize, and at the fame time is 

 lengthened in proportion. From the great regularity of 

 wire, and from its toughnefs and duftility, it is extremely 

 ufeful to all artifts who work in metal. 



The operation is called wire-drawing, and the plate of 

 ftcel a draw-plate. The machine by which the wire is drawn 

 is called a draw-bench. 



The common draw-bench is of a fimple ftrufture. A ftrong 

 plank of wood is fixed on legs, like a ftool or bench, ^^. i. 

 Plate Wire. At one end is a roller or axis. A, fixed in an 

 horizontal pofition, fo that it can be turned round by means 

 of four levers, B B, fixed like radii on the end of the axis of 

 the roller. If the refiftance is great, the workman applies 

 both his hands and his feet to the levers, to turn them round 

 in the fame manner as for a rolling-prefs. It is ufual to 

 have a ftrong ilrap, or chain, C, to wrap and wind up round 

 the roller ; and at the end of it a pair of pincers, D, are 

 hnked; thefe take hold of the end of the piece of metal, and 

 draw it through the hole in the draw-plate E, which is 

 lodged againft two ftrong iron pins, a a, fixed in the bench, 

 and ftanding up perpendicularly, fo that the plate bears 

 againft them. 



The pinoers are {hewn in^^. 2. They are adapted to bite 

 the end of the wire ; and the infide of the jaws, d d, are cut 

 with teeth like a file, that they may hold the metal very 

 tight. The oppofite ends of the handles are bent in form 

 of hooks at ^ f ; and a triangular hnk of iron f, which is 

 faftened to the end of the ftrap or chain C, embraces both 

 hooks e e, and from its triangular figure, it tends to approach 

 the two hooks at the ends of the tongs together : by thefe 

 means, the ftrain of drawing the wire clofes the pincers, and 

 makes them bite more forcibly in proportion as the wire 

 makes a greater refiftance, fo that they rarely let the wire 

 (lip. 



The draw-plate,^^j. 3 and 4, is a thick plate of fteel, with 

 holes made through it of various fizes, and in a regular grada- 

 tion from the largeft to the fmalleft. The holes are made large 

 on that fide where the wire enters, and they diminifti with a 

 regular taper to the other fide ; the goodnefs of the draw-plate 

 is an objeft of the firft importance. The diff^erent holes muft 

 diminifti by very fmall gradations, or there will be danger of 

 breaking the wire by forcing it too much at once. 



In fome draw-benches a rack and pinion are employed, in- 

 ftead of a ftrap or chain ; and a train of wheel-work may be 

 ufed like that of a crane to obtain a fufEcient power. ( See 

 _y%. 5.) If the workman turns the machine by a winch 

 or handle, it is preferable to four levers, becaufe the motion 

 is more regular ; this is of importance for fome purpofes. 

 Suppofe a piece of elaftic metal is forcibly drawn through 

 a hole in a plate with a tolerably quick motion, it will be 

 comprefled at the moment of pafling through the hole; but 

 after it quits the hole, the metal will expand a little. When 

 it is drawn very flowly, this effeft will not take place ; for if 

 the compreffion is continued long enough it becomes per- 

 manent : hence, if a piece of large wire be drawn with an 

 irregular motion, firft quicker, and then (lower, it will be 

 fenfibly larger at all the parts which pafs quickly through 

 the hole, and fmaller where it is drawn flowly : if the 

 motion is fufpended for a few feconds, that part of the wire 

 which remains in the hole will have a ring or indentation 

 round it. Tliis is moft obvious in drawing hollow tubes, or 

 copper-wire, which is plated over with gold or filver. 



In the machine which is ufed for drawing ftrong pieces 



of metal, and for the very largeft, the roller is ufually 

 placed in a vertical pofition, like a capftan, with four levers, 

 at which feveral men pufti, whilft they walk round in a 

 circle to turn the capftan, and wind up the chain which 

 draws the wire through the draw-plate. 



A powerful machine of this kind is defcribed in our 

 article Pipes, for drawing lead-pipe through a fteel plate. 



We have feen a very powerful wire-drawing machine 

 ufed for forming large hollow tubes of brafs or copper, on 

 which the power to draw the tube was obtained by a fcrew, 

 like that of a prefs. This fcrew was turned by a ti'ain of 

 wheel-work, with a fly-wheel to regulate the motion. 



Another plan, which is perhaps the beft mode for a very 

 powerful drawing-machine, is to apply the force of the 

 hydroftatic machine originally invented by Pafcal, and re- 

 vived by the late Mr. Bramah. ( See Machine, and Press. ) 

 By this means, very large wires for piilon-rods of fteam- 

 engines, and other fimilar pieces, may be rendered ftraight 

 and true with little expence. 



All thefe machines are confined to draw pieces of metal, 

 which are only a few feet in length, that is, the length of 

 the bench. But when the metal by repeated drawing 

 becomes lengthened into a regular wire, if it is required to 

 reduce it to a ftill fmaller fize, it muft be drawn through 

 fucceeding plates, by wrapping the wire itfelf upon the roller 

 or barrel, inftead of employing a long chain. This method is 

 not applicable at firft, becaufe a thick bar of iron could not 

 be made to bend eafily round a roller ; but when the wire 

 becomes fmall and flexible, it can be praftifed very advan- 

 tageoudy, and admits of drawing a very great length of 

 wire by a fmall and commodious machine. 



The common wire-mills ufed in France do not, however, 

 employ a roller or windlafs, but the pincers are attached to 

 a lever, which draws them backwards and forwards alter- 

 nately by the power of the water-wheel. 



The pincers are fo conftrufted, that the jaws open when 

 they move towards the draw-plate, and releafe themfelves 

 from the wire ; but when the pincers are drawn back from 

 the draw-plate, the link caufes the pincers to clofe and bite 

 the wire with fuch force, that they will draw it through the 

 plate. 



A machine of this kind is fliewn in Jig. 7. of the plate. 

 The bafe of the machine is a very ftrong log of timber R ; 

 one end of it is cut open to receive a wooden lever A B, 

 which moves round an iron pin or bolt n, as a centre of 

 motion ; this lever is fliaped like the letter L. To the 

 upright arm A of this lever, an iron link C is jointed, and 

 the other end of this link is formed like a ring, to receive 

 the handles of the pincers D. The pincers are fupported 

 upon a plate of iron d, which is placed in an inclined pofi- 

 tion, and there is a groove in the plate, into which the end 

 of the pin or joint of the pincers is received, and they are 

 by that means guided in their motion backwards and for- 

 wards : a a are the pins which fupport the draw-plate E ; 

 there are four of them, and the plate is faftened between 

 them by wedges. 



The end B of the lever is operated upon by cogs fixed on 

 the axis of the water-wheel, which, as it turns round, de- 

 preft'es the end B of the lever ; and the end A pulls the 

 pincers back, and draws the wire through the draw-plate ; 

 but when the cogs quit the end of the lever, it is returned 

 by means of a rope faftened to the end of B, and going up 

 to a ftrong wooden pole fixed on the roof of the building; 

 and it ads as a fpring. Wlien the pincers return, they 

 open to releafe the wire, and Aide down the inclined plate d 

 by their own 'weight, till they are near the draw-plate ; the 

 wire being all the time included between the jaws, though 

 4 they 



