The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

September, 1909 © On Oe. © © © 'THE Marine REVIEW not recountersunk as shown by C, D, E, it will make a short countersink as shown by C, B, F and is not desirable for good work. This case Fig. 71 is only likely to occur where the holes in the p'ates are la aQ\ a ---- F Ee ele Fe. punched a size less than the diameter of the rivets to be used. Fig. 72 shows what is more likely to happen and also a-mild case. There being less metal on the coun- tersunk plate this part as a rule is re- moved thus decreasing the amount of countersink desirable to make good work, A-Fig. 72 shows the part vapoted and the heavy line shows the length of the countersink when reamed. The plates B, D, F, H and K show a projection over the countersunk plates A, C, E, G and I on the opposite side of the hole. If this were all the reaming needed to make fair work there would be no objections raised, but Fig. 73 shows cases which do happen. The holes are half Fre C9. blind as shown by dotted lines. The dotted part is reamed off, the full lines showing the shape of the rivet when finished. The hole under the head of the rivet is left untouched but the rest of the 1 : en / eer ' M as cae + ' " <--/%--7 %--> I material is cleaned away by slanting the reamer until it touches the outside plate. The shaded part shows a vacancy left after the rivet is finished. Fig. 74 shows a specimen where the burr side of the plate is laid against the smooth side of the countersunk plate which, practically speaking, is punched on the wrong side. The shaded parts show the vacancy left when the rivet is finished. This is Overcome by reaming the ho'e and putting in a larger rivet as shown by Hig, 7i Fig. 75 shows a specimen of three thicknesses of plates; the shaded parts show vacancy left when the rivet is finished. This can be overcome by L7G. 72 punching the middle plate a size less, and reaming out the hole after the three thicknesses are put together. Where the rivet head covers the hole one may be deceived in the quality of the rivet when finished, but on the outside where the countersink is reamed off, the small or defective countersink can always be detected. This is the most distressing part of the whole work for the rivets must be cut out and the plates recountersunk