. Model making; including workshop practice, design and construction of models, a practical treatise for the amateur and professional . und around the pis-ton rod. The two cylinders are cast en bloc. The casting isconsiderably lighter than the pictures of the finished en-gine would seem to indicate as the smooth, external sur-face is of sheet metal which forms a ^lagging or cover-ing which encloses an air space to keep the cylinders hotand in that manner prevent, as far as possible, the con-densation of the steam within the cylinders. The draw-ings show how this space is formed, the
. Model making; including workshop practice, design and construction of models, a practical treatise for the amateur and professional . und around the pis-ton rod. The two cylinders are cast en bloc. The casting isconsiderably lighter than the pictures of the finished en-gine would seem to indicate as the smooth, external sur-face is of sheet metal which forms a ^lagging or cover-ing which encloses an air space to keep the cylinders hotand in that manner prevent, as far as possible, the con-densation of the steam within the cylinders. The draw-ings show how this space is formed, the dotted lines indi-cating the lines of the actual cylinder wall in the planview. For facing off, the casting may be mounted upon thewooden face plate with the casting centered. After thecut is taken, the work may be reversed to face the otherside. The casting is then scribed accurately with centerline and the two holes spotted to indicate cylinder casting is again mounted, but this time the center is1)rought up to one of the spot marks indicating one cyl-inder bore. After clamping securely, the casting may be 162 Model Engineering. Fig. Ill—The parts of the finished engine A Model Twin-Cylinder Marine Engine 163 drilled, but first of all the whole job should be balancedby bolting a small mass of metal to the side of the faceplate to compensate for the lack of balance and to pre-vent vibration which would destroy the accuracy of thework. The boring of one cylinder finished, the castingmay be changed over so that the other may be bored. The casting ma}^ then be removed from the face plateand the ports drilled and chipped out. Before doing thisoperation, however, the slide valve faces may be ma-chined. The right way to do this is on an angle platein the lathe after the cylinders have been bored andfaced off. An alternative method is to file and grind theface true, or. as nearly so as the skill of the worker willpermit. The little kink used for the slide valve rod is a
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Keywords: ., bookcentury1900, bookdecade1910, bookidmodelmakingi, bookyear1919
