Locomotive boiler construction; a practical treatise for boilermakers, boiler users and inspectors .. . specified. Fig. 65 shows a shearing punch which gives a veryclean hole and from the enormous number of holes thatsuch a punch can make, it would seem to indicate that themetal was cut rather than torn during the process ofpunching. This figure shows the shape of the sheet 103 Laying out tubes. after the punch has advanced about half way on itsstroke. When these sheets are punched it is impossible,on account of the construction of the machine, to getclose enough to the flange of the sheet unl
Locomotive boiler construction; a practical treatise for boilermakers, boiler users and inspectors .. . specified. Fig. 65 shows a shearing punch which gives a veryclean hole and from the enormous number of holes thatsuch a punch can make, it would seem to indicate that themetal was cut rather than torn during the process ofpunching. This figure shows the shape of the sheet 103 Laying out tubes. after the punch has advanced about half way on itsstroke. When these sheets are punched it is impossible,on account of the construction of the machine, to getclose enough to the flange of the sheet unless the flangeis turned up toward the punch. This, of course, meansthat the work of laying out the sheet must be upon theinside instead of the outside of the sheet. C is a springcenter; once having centered the sheet upon the punchand thrown the gag of the punch in position, this centerpresses back out of the way and is always in good condi-tion. The usual lay-out of tubes is to comply with thespecifications, which read a certain number of tubesspaced so far apart. The bridge between the tubes, see. Figuije 66Layout for tubes. Fig. 66 at B, is usually from ^s to 11/i6 °* an incn- Oncein a while this space is cut down to one-half of an inchand less. While this cutting down process does admit ofa little greater apparent heating surface by allowing a 104 Punch for long curved lines. few more tubes, yet the liability of these bridges breakingat B is too great to warrant its being made any less thany2 inch. Then, too, it must be remembered that thesetubes are not all straight, that mud collects between them
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Keywords: ., bookcentury1900, bookdecade1910, bookidlocomotivebo, bookyear1912
