Fig. 2510.
The cylinder covers must, after being drilled, as above, be taken from the cylinder, and the clearing drill put through the holes already drilled so that they will admit the bolts or studs, the clearing holes being made 1⁄16 inch larger than the diameter of the bolts or studs. The steam chest may be either clamped to the cylinder, and tapping holes drilled through it and the cylinder (the same as done in the case of the covers), or it may have its clearing holes drilled in it while so clamped, care being taken to let the point of the drill enter deep enough to pass completely through the steam chest, and into the cylinder deep enough to cut or drill a countersink nearly or quite equal to the diameter of the drill. If, however, the steam chest is already drilled, it may be set upon the cylinder, and the holes marked on the cylinder face by a scriber or by the end of a piece of wood or of a bolt, which end may be made either conical or flat for the purpose, marking being placed upon it; so that, by putting it through the hole of the chest, permitting it to rest upon the cylinder face (which may be chalked so as to show the marks plainly), and then revolving it with the hand, it will mark the cylinder face. This plan is generally resorted to when the holes in the chest are too deep to permit of being scribed. To true the back face, round a hole against which face the bolt head or the face of the nut may bed, in cases where such facing cannot be done by a pin countersink or a cutter used in a machine, the tool shown in [Fig. 2510] may be employed, a being a pin provided with a slot at one end to admit the cutter b, which is held fast by the key c, and is also provided with a square end f, by which it may be turned or revolved by means of a wrench, and with a thread to receive the nut e, d being a washer; so that, by screwing up the nut e, the cutting-edges of the cutter are forced against the cylinder g, and will, when revolved, cut the face, against which they are forced, true with the hole in the cylinder through which the pin a is passed.
After the drilling the cylinder should be placed on end and all the holes that can be got at should be tapped. Then the cover joint, supposing it to be a ground joint, should be made according to the directions given for making ground joints, when the cylinder may be turned upside down and the other cover fitted. Then the holes for the cylinder cocks and for the steam and exhaust pipe should be tapped, and the faces for these pipe joints fitted as required.
The steam-chest holes should then be tapped and the ports marked out and chipped and filed to the lines, such lines being marked as described in the remarks on lining out work.
The face for the steam-chest seat and the steam-chest cover may then be prepared by filing, scraping, or grinding, as may be required, and simultaneously the valve seat and valve face may be fitted. If the cylinders are to be bolted together as in a locomotive, the holes for holding them together should be drilled about 1⁄64 inch smaller than the bolts, so that they may be reamed out together after the cylinder bores are aligned.
One cylinder face should be marked and drilled first, and the two cylinder bores being set to align true the other cylinder should be marked from the other, or if there is a saddle between the two cylinders both cylinders may be marked and drilled, and also the holes on one side of the saddle. Temporary bolts may then be put through the holes that are drilled in the cylinder and saddle and clamps used to hold the undrilled cylinder to the saddle, when the cylinder bores may be set true one to the other, and the holes on the remaining side of the saddle marked through those already drilled in the cylinder. These latter holes being drilled, temporary bolts of smaller diameter than the holes (so as to give room to move the cylinders to align their bores) may be used to bolt the cylinders together while their bores are accurately aligned, which alignment may be effected as follows:—
Fig. 2511.