. Model engine construction, with practical instructions to artificers and amateurs. after which the borewill be found quite true and perfectly circular, ifthe cylinder has been properly chucked. A secondcut can be taken by means of a rose-cutter (slightlytapering at the point only), while the cylinder isstill chucked; and after this has gone through, thecylinder will be found perfectly true and as smoothas glass inside. This second cut is not absolutelynecessary, if the steel cutter has been well made,with the four cutting edges perfectly parallel toeach other, and of a temper hardened, so as
. Model engine construction, with practical instructions to artificers and amateurs. after which the borewill be found quite true and perfectly circular, ifthe cylinder has been properly chucked. A secondcut can be taken by means of a rose-cutter (slightlytapering at the point only), while the cylinder isstill chucked; and after this has gone through, thecylinder will be found perfectly true and as smoothas glass inside. This second cut is not absolutelynecessary, if the steel cutter has been well made,with the four cutting edges perfectly parallel toeach other, and of a temper hardened, so as toremain quite sharp during the whole of the drillingprocess. A little oil can be used to facilitate boring G 82 MODEL ENGINE CONSTRUCTION. operations. The cylinder is now smoothed all overwith a file, and can be painted where it has notbeen turned. It will be noticed that as yet thesteam- and exhaust-ports have not been bored (see Fig. 26). In large cylinders thesteam-ways are cast in; in small models they mustbe drilled. Take the cylinder, square up the valve-. Lines scribed on cylinder valve-face, where they intersectparts, must be drilled. Fig. 26. face, and flatten it by filing; measure off and drawa vertical line through the centre. Now draw twovertical lines, one being on either side, each distantabout two and a half times the width of the finishedsteam-port from this central line. Next draw a hori-zontal centre line, where these lines intersect each THE STEAM-ENGINE. 83 other; punch three holes to form the ports—themiddle one is for the exhaust, the outer ones for theadmission of steam. Next mark the steam-ports onthe face of each flange, not far from the bore; punchthese holes, which must be drilled in the middleline, of the thickness of the ridge that runs from thevalve-face to the cylinder mouth. Fix the cylinderin the vice, drill the exhaust-port for a short distanceinwards, but stop short of piercing the bore; drilla hole to meet this one at righ
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectmachinery, bookyear18
