Locomotive boiler construction; a practical treatise for boilermakers, boiler users and inspectors .. . restsupon the die. In order to bring the sheet up to the punch, and enterthe tit of the punch into the center punch mark, it isnecessary to press upon the sheet at A or B, or both, andoverbalance the sheet, thus bringing it up against thepunch. The tit should be well entered into the centerpunch mark. Here lies the cause of so much trouble inpunching. The action of the punch is so rapid that if thetit is not entered good and solid in the center punch mark,the hole will be punched through the
Locomotive boiler construction; a practical treatise for boilermakers, boiler users and inspectors .. . restsupon the die. In order to bring the sheet up to the punch, and enterthe tit of the punch into the center punch mark, it isnecessary to press upon the sheet at A or B, or both, andoverbalance the sheet, thus bringing it up against thepunch. The tit should be well entered into the centerpunch mark. Here lies the cause of so much trouble inpunching. The action of the punch is so rapid that if thetit is not entered good and solid in the center punch mark,the hole will be punched through the plate out of not infrequently happens that holes are punched toone side of the center and although this matter may notbe so serious in the case of a stay bolt, yet if a rivet holeis punched out of center, it makes a very bad job to fix up. 108 Method of holding sheet. Fig. 72 shows the way a sheet is supported over a-horizontal punch. An eye bolt E is placed through somepunched hole so that it will about balance the sheet andthen raised and lowered by a hand crane to suit. T is the C^)T. Figure 72 Dsrry Collard Co. Method of supporting sheet for punching. trolley which has a movement back and forth along thejib crane J. After the work has been laid out upon thesheet, a good substantial center punch mark should bemade in the sheet at every position where a punched hole 109 Shearing. is required. Before these holes are punched, each one ofthese places should be given a dab of grease, so as tolubricate the punch and increase its life. Shearing.
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Keywords: ., bookcentury1900, bookdecade1910, bookidlocomotivebo, bookyear1912
