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THE INDIA RUBBER WORLD 



[December i, 1903. 



panies have adopted the practice of making the short capped 

 end lengths at once, thus effecting a saving in cost and beside 

 securing perfect exactness as to dimensions and enlargement of 

 ends; better workmanship throughout producing goods more 

 accurately capped and free from twists and internal convolu- 

 tions of the duck which produce serious irregularities in the 

 tube thickness. Hand made tube for hose seems to receive the 

 special endorsement of many users of air brake and other hose. 



In this particular as in most others it is true that machine made 

 goods are more uniformly reliable than hand made. High 

 grade stock carefully refined and run from a tubing machine 

 will produce a better inner tube for hose than can be made of 

 the same stock by hand from a sheet because being seamless it 

 is free from the liability of careless work in seaming Hp in the 

 presence of soapstone dust which must be used, and is always 

 liable to enter the seam and render the joint defective. 



RUBBER FACTORY METHODS AND APPLIANCES. 



MAKING PERFORATED RUBBER MATS. 



PERFORATED or punched rubber mats are generally used 

 in vestibules, elevators, and carriages, and are of sufficient 

 importance to warrant more care and thought in manu- 

 facture than they generally receive. It is a frequent 

 mistake to make these heavy low grade goods in sections of too 

 great area, and they consequently get broken up long before 

 they should, and the purchaser puts the blame just where it 

 belongs, on the manufacturer, who should make his goods of 

 whatever kind with some idea of adaptability to use. Another 

 important point to be considered is the size of the perforations 

 employed. They should not be large enough to permit the 

 fingers to pass easily through them. For in that case the mat 

 will surely be lifted about in this way and soon be broken, es- 

 pecially if the angles of the perforations are sharp instead of 

 being rounded, which will ser 

 cure greater resistance to tear- 

 ing. 



Mat stock generally is run 

 in rolls, built up in plies in the 

 calender on a sheeting back. 

 The thickness usually is %, %, 

 or % inch.. In making a mat 

 the stock, of suitable size to al- 

 low for shrinkage in curing 

 and trimming, is cut approxi- 

 mately by the pattern of the 

 area to be covered. If it is to 

 contain any inlaid letters or 

 monograms these are put in 

 at this stage by removing one 

 ply of the mat stock and ce- 

 menting in the colored letter 

 stock. The stock is next 

 semicured in a hydraulic press, 

 on a smooth or corrugated 

 plate according to the surface 

 desired on the mat. 



Before laying out the guide lines for the perforations the 

 cloth back must be removed. This is accomplished by thor- 

 oughly wetting the sheeting with naphtha, and while still wet 

 carefully drawing it back from the edges until it is entirely free 

 from the stock. Great care is necessaryat this point to prevent 

 ignition of the naphtha gas by an electric spark due to friction. 

 There is very little danger if plenty of naphtha is used, because 

 thecloth will then separate very easily. The dangercomes with 

 the increased friction due to not wetting the cloth well with 

 naphtha, and to undue haste in withdrawing the sheeting. 



Guide lines for the pattern or design are marked on the 

 stock and properly spaced to bring the perforations even all 

 around. This can easily be done by carefully spacing the pat- 

 tern both ways with the dividers and allowing the small amount 



of odd space not needed in the center or border to go into the 

 plain margin. 



The various cutting dies are provided with handles and are 

 driven through the stock with a mallet. A most convenient 

 form of mallet is similar to that used by a stone cutter. It is 

 made of firm fiber and rubber stock, weighing about 3 pounds, 

 and fitted with a stout handle of hickory. The pattern is 

 punched out with reference to the guide lines (as indicated in 

 the accompanying figure) and carried across all the lettering by 

 lightly applying the dies in such a way as not to mark the let- 

 ters, but only to indicate faintly the parts of the design adja- 

 cent to the lettering but not completely overlaid by them. In 

 this way the irregular perforations are indicated and are subse- 

 quently cut out with the aid of chisels, of which a considerable 

 variety of sizes is needed. After perforation the mat receives 



a final cure in open steam heat 

 and the surface is finished by 

 a simple application of harness 

 soap or black lead in water and 

 rubbed to a polish with a 

 brush. In this way a very at- 

 tractive finish is obtained and 

 all traces of the guide lines 

 used in the laying out of the 

 mat are removed. Colored 

 letters are wiped off with a 

 little naphtha on a rag and 

 the mat is completed by trim- 

 ming to size. 



This method of mat making 

 is much more satisfactory than 

 the old plan of punching the 

 pattern through a stencil made 

 of thin packing lightly cement- 

 ed over the stock, or the other 

 crude way of dusting the pat- 

 tern onto the stock with chalk 

 through a stencil. These methods are still in use, however, 

 and certainly seem awkward when the design requires to be 

 stenciled on the back of the stock, in the case of a corrugated 

 mat, and the perforations punched out from the back. 

 MULTIPLE PLY INSULATION FOR WIRES. 

 A most perfect method for rubber covering electric wires 

 has of recent years been discovered or developed, which prac- 

 tically supersedes the older method of drawing a single wire 

 through the head of a tubing machine and forcing the rubber 

 stock out around it as it passed through the die regulating the 

 amount of stock applied. The newer method is designed to 

 cover several wires at one and the same time, with one or more 

 plies, but generally two, each ply united around the wire by a 

 " butt " seam and made from calendered sheet stock. By this 

 plan of insulation some very important advantages are secured 



