804 



THE INDIA RUBBER WORLD 



August 1, 1921 



method is preferred by experts as being far more certain and 

 durable. It is illustrated on the preceding page, and con- 

 sists in punching two rows of holes in each belt-end, the second 

 row to be the same distance from the first as that is from the 

 end of the belt, so that each hole in the second row centers be- 

 tween the nearest two holes in the first row. The holes and lace 

 size should be as shown in the following table : 



Width 



of Relts 



Up tu 



3 



3 to 6 . . 

 6 to 12. 



nches 



12 to 18 5/16 



Proportionate allowance should be made for larger belts. 



The lace should be started in the center hole in the first row 

 to the opposite hole in the second row and continued in such a 

 way that the lace shall be straight and smooth on the pulley side, 

 and crossed on tlie back of the belt. Having been begun in the 

 center, the lacing should be looped through the holes first toward 

 one edge, brought back to the center, crossed to the other edge. 

 and then continued back to the center, finishing with both ends 

 of the lacing in the same hole, but entering it from opposite sides 

 of the belt. A hole is then made with a belt awl about J^-inch 

 from the hole at which the laci'ng was started and finished, both 

 ends of the lacing are tucked through this awl hole, pulled tight 

 and cut off, leaving ends about }/^-inch long. 



SPACING HOLES FOR DOUBLE-GRIP LACING 



The ends of the belt having been squared accurately, after the 

 centers of the outer holes in the first row have been determined 

 according to the aforementioned table, the intervening distance is 

 divided into an even number of spaces made as nearly equal as 



possible to the distance that 

 the outer holes in the row 

 are from the edges of the 

 belt, but taking care that the 

 division length does not ex- 

 ceed this distance between 

 tlie outer holes and the butt 

 joint. 



Holes are then punched 

 at every point in the first 

 line, and at the intermediate 

 points in the second row, 

 the diameter of the holes be- 





Laying Out Lace Holes 



ing about three-fourths the width of the lacing. 



In making holes in rubber belts many good mechanics prefer 

 to cut oval-shaped holes with double strokes of a round punch, 

 but experts always use an oval punch, leaving the longer diameter 

 of the oval parallel with the belt sides. A pointed awl is advised, 

 instead of a punch, by some manufacturers. 



HINGE JOINT LACING 



Where leather lacing is used on small rubber belts running at 

 high speed over small pulleys it is considered advisable to make 

 the lace form a hinge. In this case the holes are punched in the 

 staggered form used for the double-grip lacing already described, 

 and the lacing is also started at the center; but instead of lacing 

 straight, the leather strip is passed over and under, always lacing 

 toward the outside. 



LACING AND LAP FASTENING 



Many users of belts 12 inches wide or over have found the 

 following lacing and lapping method very satisfactory. Up to 

 and including 12-inch belts, the latter are cut with 12 inches to 

 spare, but beyond that size the excess is the same in inches as 

 the belt is wide. If the belt is 4-ply, take ofif two plies on one 

 end back 12 inches or more, according to the width as here il- 



lustrated. Then take the same amount off the other end, in such 

 a way that the two prepared ends lap squarely together. The 

 illustration shows the lap made as directed and the holes punched 

 for lacing. If the belt has three plies, two plies should be taken 



The Back Splice 



off' one end and one ply off the other ; for 5-ply, three and two plies, 

 respectively ; for 6-ply belts, three plies off each end, and so on, 

 all being punched as shown in the illustration. 



Light lacing is used for all 3-ply belts, and proportionately 

 thicker lacing for the heavier and wider belts. The holes punched 

 should be the smallest possible to admit the passage of the lacing. 

 No cement is necessary if directions are closely followed. 



MAKING A BACK SPLICE 



On wide belts run at liigh speed, or where there is great strain 

 and it is not convenient or desirable to use a cemented or riveted 

 lap splice, a back splice will add much to the life, safety, and 

 efficiency of a butt-jointed belt, although it is not suitable for 

 belts running under an idler. 



In making a back splice the butt ends of the belt are brought 

 tightly together and a piece of belting put over the united ends 

 as a reinforcement. This piece is usually equal in length to the 

 width of the belt, but in some cases it may be made as short as 

 half the width or as broad as one and one-half the width. The 

 ends of this reinforcing piece should be skived to a feather edge, 



otherwise the splice 



will bump in passing 

 around pulleys. It is 

 fastened with leather 

 lacing or rivets. 

 LAP-SPLlClNG 

 When it is not con- 

 venient to get an end- 

 less belt from a man- 

 ufacturer, a very sat- 

 isfactory lap splice 

 may be made by a 

 careful mechanic that 

 will be serviceable on 

 belts of all sizes and 

 particularly on those 

 of much breadth. The 

 ends having been cut 

 absolutely square, the 

 splice is made by 

 "stepping" the ends of 

 the belt for a distance 

 equal to or greater 

 than the width of the 



.^L. 



Fio. 3. 



Lace and Lap Fastening 



belt, being careful not to cut a lower ply while cutting for the one 

 above. Hence a 4-ply belt should have four "steps," a 6-ply, six 

 "steps," etc. The measurements of the steps should be equal. 



