model locomotiveFig. 2.
Fig. 2.
At the commencement of this chapter is adrawingof the model we are about to build in its finished condition, andFig. 2is a side view of the same, of whichAis the boiler,Bthe chimney,Ca screw head to fill boiler with water,Dthe steam chest with safety valve on top,Ethe whistle,Fthe steam tap to start the engine with,HHare the leading and trailing wheels, andIthe driving ditto,Kthe cylinders,Ltheframe,Mthe buffers,Na set thumb-screw to fasten a tender on by,Ois the lamp, andPis a small tap, used to ascertain the quantity of water in the boiler. The handrailsRandScomplete it; and I think this is sufficiently clear for you to perfectly understand the general working arrangements of the model.
Locomotives, whether real or only model ones, can all be divided into three principal parts, viz., the carriage or framework, the engine or cylinders and parts connected with them, and the boiler, and we will now proceed to make each part in turn, beginning with the framework.
model locomotiveFig. 3.
Fig. 3.
First take a sheet of brass for the bed-plate, about one-sixteenth of an inch thick, and cut it to an oblong shape, four inches wide by fourteen inches long, as inFig. 3, and be very careful that the corners are right angles. This is to be hammered out quite flat and filed up smooth, and finished with emery cloth held round a flat piece of wood; you must also cut a hole in it for the boiler to rest in as atC, beginning half an inch fromBand making the hole eleven inches long by one inch and a half wide, taking care it is quite central on the lineAB, or you would get your engine lopsided, and you must take the same care in setting the chimney, steam dome, etc., as when not exactly central it gives a bad unsightly look to an otherwise well-finished model.
model locomotiveFig. 4.model locomotiveFig. 5.
model locomotiveFig. 4.
Fig. 4.
model locomotiveFig. 5.
Fig. 5.
The next step is to cut out the side frames (Fig. 4), drilling holes atA B Cfor the axles to work in; you can finish both sides in the same way, and, turning the bed-plate upside down, fasten the frames on at a quarter of an inch from either side by small angle pieces, as inFig. 5, or by soldering, which is much quicker. Then fasten by the same means a piece across each end about half an inch deep, and the frame is ready for the wheels.
model locomotiveFig. 6.
Fig. 6.
These can be had ready finished, but if you have the castings, they must be chucked in the lathe and the tires turned up to the form shown inFig. 6. The small wheels should be about two and a half inches diameter and the driving wheels four inches. The rimBshould project a little over one-sixteenth of an inch, and the rest of the edge should be bevelled off slightly as atA.
The spokes may then be filed up smooth, previously drilling out the centre hole for axle before removing it from the lathe.
model locomotiveFig. 7.
Fig. 7.
Great care must be taken to turn both the driving-wheels to exactly the same diameter, or one wheel would travel farther in a revolution than the other, and as they ought to be both fixed rigidly on to the crank shaft, the engine would never travel in a straight line, but would always run in a circle. You will require some steel wire for the axles, and can fasten them to the wheels by soldering or by cutting a slot with a fine file in the centre of wheel, as atA,Fig. 7; then filing a small portion of the ends of the axle flat, drive in a brass wedge made from a piece of wire, which will hold them together firmly.
The crank shaft or axle must be hammered up to shape, making it hot occasionally in the gas flame whilst working it.
model locomotiveFig. 8.
Fig. 8.
The cranks should be at right angles to each other, and the throw of the crank is to be half the distance of the cylinder stroke. For instance, say the cylinders are an inch and a half in stroke, the distance betweenA B(Fig. 8) will be three-quarters of an inch; you must then ease the size of crank atA, to prevent the piston knocking the cylinder ends.
The cylinders require such extreme care in turning that it is by far the best plan to buy them ready to put on your framework; and if you get a pair of oscillating ones three-quarters of an inch bore and about an inch and a half stroke, you will get sufficient power to drive your locomotive several miles an hour.
model locomotiveFig. 9.
Fig. 9.
Fig. 9shows you an underneath view of the framework and the position to place the cylinders in, which should be supported by a couple of lugs (A A) screwed to the bed-plateBwhich must have a piece cut out on either side to allow the driving-wheels (C) to work in, as atD, because, being larger than the others, they project beyond the top of the bed-plate, as shown inFig. 2. You can now screw on by means of the hookFthe buffer-beam, previously cut from a piece of mahogany, five inches long, half an inch thick, and one inch deep, nicely squared and sand-papered.
Drill a hole atGand pass the shank of hook through the beam and piece of brass in front of frame, and screw up tight with nutH.
The buffers can be properly turned up and fitted with springs, but that I will explain when making our more perfect model, and content ourselves now with a couple of brass flat-headed screws, such as are used in connections of electric batteries, and which form capital imitation buffers, one having to simply screw theminto the beam about one inch from either end, leaving them projecting about half an inch.
The framework is now sufficiently complete to be lacquered. First polish every part intended to be bright, carefully removing all traces of file-marks and any grease that may be on the work by a little acid; and after drying it place it on a sheet of iron held over the gas—or fire, if clear—until it is moderately warm. You can then apply the lacquer with a small brush, taking care not to go over any part more than once. The lacquer can be had at most model shops, and is cheaper to buy ready-made than to prepare yourself.
The spokes of the wheels should be painted; black-lined on green looks very well, and the ordinary tube oil-paint, mixed with a little mastic varnish, is the best to use.
The buffer-beam should be varnished, and the cylinders ought to have a coat of paint, leaving the cylinder-covers and the flanges bright.
model locomotiveFig. 10.
Fig. 10.
The frame may now be put aside to dry, covered up from dust by a paper box, whilst we proceed to make the boiler (Fig. 10).
This is a most important part of the locomotive, and is the cause of a great many failures and unsatisfactory working, even amongst the professionally-built models. I well remember how, when a lad at school, I fell deeply in love with a beautiful highly-polished brass locomotive of about the size we are now building, which was displayed in an optician’s window. Having made inquiries about the price, and got it reduced from to £5 to £4, with a promise to keep it for me, I set to work to save my pocket-money, and for some months rigidly abstained from all kinds of tarts and toys; and when finally the last shilling was saved which completed the amount, and I carried it—my first model—home in triumph, no boy was ever happier. But, oh! the bitter disappointment when, after getting up the steam and trying to start the engine, I found it would not work.
I was too young then to find out the reason, and the man who kept the shop, not being a practical mechanic, could give me no help, and although, after we had tried it together, he offered to take it back, I decided to keep it with a view to remedy the defect, if possible; but it was a long time before I found out that the fault lay in the boiler not being able to supply sufficient steam for the cylinders, in consequence of not having enough heating surface acted on by the lamp.
Since that day I have made numerous models, and have always taken precautions to avert such a difficulty, and although the method I am about to describe entails a little extra work, you will feel well repaid for the trouble when you find what a splendid head of steam can be kept up.
The boiler should be eleven inches long by three inches and a half in diameter, and you can buy copper tubing of that size which is very suitable for the job, or you can form it from a sheet of copper or brass bent to shape round a wooden roller, and either riveted or soldered together. You must then turn two circles of brass about an eighth of an inch thick for the ends, and polish the outside of each nicely.
model locomotiveFig. 11.
Fig. 11.
Then push them into either end of the boiler about an eighth of an inch from the edge, as inA(Fig. 11); they can now be soldered in place, and you will find your gas blow-pipe very useful here. The projecting flange should be hammereddown all round, likeB(Fig. 11), which can also be sweated afterwards with solder, and finished off with a half-round file.
When filing solder or lead, only use an old worn file, as the soft metal soon fills up and spoils a good one, and although it can be melted out by heat, it is not advisable to do so.
You will now require to drill a hole atA(Fig. 10) for the chimney, which should be three-quarters of an inch in diameter. Then cut a slot in the bottom of the boiler six inches long by an inch and a half wide, commencing a quarter of an inch from the forward end of the boiler.
model locomotiveFig. 12.model locomotiveFig. 13.
model locomotiveFig. 12.
Fig. 12.
model locomotiveFig. 13.
Fig. 13.
model locomotiveFig. 14.
Fig. 14.
Now take a sheet of copper and cut a piece about six inches and a quarter long by six inches broad, and bend it over a wooden roller to the shape shown atFig. 12, keeping it an inch and a half apart betweenA B. Cut also two other pieces of copper to the shape of your bent sheet (Fig. 12), and make it long enough to reach to the dotted line. These form the two ends, which may be placed an eighth of an inch from the edges, as inFig. 13, and soldered in place, and the projecting rims turned over and sweated with solder from the outside in the same manner as you did to the boiler-ends inFig. 11. Then drill a three-quarter-inch hole atB(Fig. 13) for the bottom of chimney-tube to go into, and cut a piece of three-quarter-inch brass tubing of sufficient length to pass out at top of boiler about half an inch, as shown atA(Fig. 10). You can then hammer out a rim or flange on the bottom end of chimney-tube, and push it up through the hole in the copper box and solder it in place from the top, as atA(Fig. 14).
Now drill a couple of small holes at each end of the boxB C(Fig. 14); these should be rather more than an eighth of an inch in diameter, to allow an eighth of an inch tube to pass through.
Get two twelve-inch lengths of hard-drawn steam-piping of an eighth of an inchin diameter, and with your screw-plate put a thread on each end of about half an inch in length, then drill some holes in any odd piece of brass plate, and with the screw-taps form eight nuts to fit the threads on the piping, and finish them up to shape with a file.
model locomotiveFig. 15.
Fig. 15.
Then take the piping and bend it very gently, to prevent it cracking, round a bar of iron or handle of some tool held in the vice until it is of the form shown atFig. 15. Do each one the same, and then mix a little turps with some white lead and smear each end where you have formed the screws, taking care not to get any into the tubes, and they might have a plug of paper put in temporarily to prevent it.
model locomotiveFig. 16.
Fig. 16.
Now put a nut on at either end as far as the thread will allow it, and smearing a little white lead round the holes drilled in ends of boxB C(Fig. 14), push the tubes in from the inside and screw up firmly with the remaining nuts in the position shown atFig. 16. The inside nuts can then be tightened up with a spanner, and if you have carefully done this you will never be troubled with any leakage, no matter what pressure you may get in the boiler.
These tubes are immensely strong, and from their small size the water in them is raised quickly to a higher temperature than that contained in the rest of the boiler, causing a continual circulation to take place and a constant supply of steam to be formed.
The box can now be placed in the boiler through the slot cut in the bottom, taking care that the top of box is not more than half way up the boiler, as inB(Fig. 10). This will leave a portion projecting below the lower edge of boiler, likeC. This part protects the flame of the lamp from being blown away by the draught caused by travelling along, which would cause you to lose steam. Solder it firmly in position from the outside, to prevent the flame touching any soldered portion. Also solder neatly roundA(Fig. 10).
model locomotiveFig. 17.
Fig. 17.
The chimney can be made from another piece of three-quarter brass tube. Chuck it in the lathe, and turn it up bright, and put a collar on it atA(Fig. 17) to allow it to push on to the piece of tube left projecting atA(Fig. 10).
The top of chimney, or bell-mouth,B(Fig. 17), will require turning in the lathe also, and fitting on neatly.
The steam-chestD(Fig. 10) is a brass casting you can turn up also, and after cutting a circular hole in top of boiler of about an inch in diameter it can be either screwed or soldered on, previously putting the steam-pipeEin position by drilling a hole atF, and after bending it as shown, pass it through atFand solder in place.
The top of pipeEshould be about a quarter of an inch from top of inside of steam-chest.
Before soldering on the steam chest drill a couple of holes, as atG H(Fig. 10), one for the small lugGto be screwed into, which holds one end of the lever of the safety valve, and that atHshould be drilled conical with a rhymer, and the valveHcan be turned in the lathe, and afterwards ground to fit the hole with a little emery and water, by means of a slot cut across the top and worked round with a screw-driver.
The spring-case of safety-valve is easily made from a piece of the one-eighth of an inch brass tubing, and using some small, hard brass wire to form the spring of. When finished it should be hooked to the eye screwed into boiler atV.
The manhole, or screwhead,K, is used to refill the boiler by when it has steamedlow, and will require to be turned up to shape; and the bedLit screws into can be firmly soldered on the boiler, having first drilled a hole slightly larger than the diameter of the screw itself, which should be sufficiently large to allow an ordinary tin funnel to be used to refill by, and the screw ought to be large enough to hold a leather washer under the head to keep it steam-tight.
The whistleMwill require a hole drilled for it to be screwed into, and that, as also the steam-tapNand water-tapO, can be bought cheap ready to put on, and is more satisfactory than making them yourself. But should you wish to do so, the method I have already described in Chapter X. of making an oil-cup applies equally to these.
The tapOshould be screwed in at a slightly higher level than the top of boxB, and when working the engine, should steam issue from it when turned on instead of water, you ought to immediately blow off steam by safety-valveH. Then unscrewK, and refill the boiler with water.
By this time the framework will no doubt be quite dry, and you can then clean and polish the boiler and attach it to the frame by a screw or solder at the forward end, and the steam-pipeNcan be screwed on to the projecting piece of tube left atF, whilst you also screw a short length of pipe into the steam-box of engine through a hole in the bed-plate. Then bend it up to the steam-tap and solder them carefully in position; this will hold the after end of boiler firmly.
Go over every soldered joint to see if any small hole is left, and re-solder where necessary, as a hole in the boiler not larger than a pin’s point would prevent you getting any adequate pressure of steam, as the water would all blow out.
model locomotiveFig. 18.
Fig. 18.
When so far complete, you can either lacquer or paint the boiler as suits your fancy, and whilst it is drying there will be time to make the lamp (Fig. 18).
It is simply an oblong box made of tin or any piece of thin metal you may have, and should be one inch and a quarter wide by five inches long, and about three-quarters of an inch deep. To make it, cut say a piece of tin four and a half inches by five inches, and bend it to shape, then solder the two edges together and cut two ends to fit. Push them in and solder in place.
Then cut three pieces of brass quarter-inch tubing into three quarter-inch lengths, drill holes in top of lamp and insert them, allowing about a quarter of an inch to project, as atA(Fig. 18); then solder them on four pieces of bent wire (C C C C), by which to hang the lamp by means of two wire pins run through them and small holes drilled in sides of projecting pieceC(Fig. 10).
The screw-fillerB(Fig. 18) will have to be soldered in also, and when complete the tubesAmay be filled with cotton wick, and the lamp about three parts full of methylated spirit, which will give a clear smokeless flame.
You can now start your locomotive by filling the boiler about three parts full of hot water, and then hooking the lamp underneath; you will soon get a good pressure of steam up.
See that all the taps are turned off; and if there is no leakage from careless workmanship, you will find, on turning the steam-tap on, the locomotive will run beautifully, and will travel at great speed either on a smooth oil-cloth or wood floor.
model locomotiveFig. 19.
Fig. 19.
I will presently explain how to make a set of rails, on which she would run much quicker still; but for this engine, if you make a small tender of the shape shown atFig. 19, and fasten it at any angle by the set-screw on the foot-plate of the engine shown atN(Fig. 2), the model will run in any sized circle you may wish, without lines, according to the angle at which you fix the tender to the engine.
Wooden coal trucks, etc., you can easily make to complete the train if you wish; but of course each one is an extra load for the engine to draw, and will prevent it going as quickly as when alone.
Tin is the best material to use for the tender, as no great strength is required; indeed, it should be made as light as possible. The wheels and axles you must finish in the same manner as those on the engine; and it could be made into a tank, to hold an extra supply of spirit, by soldering a piece of tin round the inside, and covering it in with another piece cut to shape, and fitted with a screw-nut to fill by, as shown inFig. 18.
If you have carefully followed these simple directions, and also practically carried them out, you will be able, and no doubt anxious to try your constructive powers on a more complete model, and I will therefore endeavour to help you to do so.
Should you be able to draw, you will find it a great help if you carefully sketch out on a sheet of cartridge paper the locomotive to the exact size you intend building it.
You can then take all the measurements from it, which will prove to be a saving in time and trouble. Of course the larger you make the engine, the more expensive the castings and materials will be; but if you persevere in making the locomotive I am about to describe, you will have a model of real value to you, and which would probably cost fifty pounds to buy ready finished; and if you turn the wooden models for the castings yourself, and use sheet-iron for the framework, etc., where possible, the total expense will not be so very great.
Fig. 20is a side view of the locomotive in its finished state, and we will begin to work at it in the same manner as in the former model, viz., with the framework; but as some of my readers may have a preference for some special type of engine other than the one drawn, they can easily build it from the following directions, and keeping the same proportion in size as inFig. 20, which is drawn to1⁄8-inch scale.
The entire length should be about three feet two inches, and the bed-plate thirty-five inches by nine inches wide. The driving-wheels are eight and a quarter inches in diameter, and the leading wheels five and a quarter inches, and about six and a half inch gauge, viz., the space between the lines on which the wheels run.
The cylinders should be one and three-quarter inch bore by two and a half inch stroke, which will give sufficient power to drive the engine at a high rate of speed, with 30 lb. to 50 lb. of steam. The boiler is twenty-eight inches long, including smoke-box, by five inches diameter.
model locomotiveFig. 20.
Fig. 20.
Fig. 20 enlarged(200 kB)
InFig. 20I have lettered the various parts, and it will be well to look over them carefully, as this engine differs materially from the previous model in its arrangement, being constructed exactly similar to a real engine.
Ais the chimney,Bsteam-blast used to increase the intensity of the fire, and is worked by rodCrunning through the hollow handrailD, and ending in handleF.Gthe steam-dome and safety-valve is the same pattern as previously used,Hextra safety-valve, worked from foot-plate;Isteam-whistle,Kwind-guard,Lstarting-lever,Msmoke-box (with door),N Ospring-buffers;Pis the line-clearer, or wheel-guard;Qleading wheels, andR Rdriving ditto;Sone of the cylinders, with piston-rod and guides bolted to frame, and showing double connecting rod atT T;U Uare the springs which support the weight of the boiler, etc., on the axle-bearings; the spring on rear wheel does not show, being inside the safety-guard and handrailV.Wis the back-pressure valve, through which the water is thrown by the force-pump into the boiler; andXis the blow-off tap to clear the model from all water after having used it; andYshows the side of ash-pan.
model locomotiveFig. 21.
Fig. 21.
Now to commence making the framework. This should be made of one-eighth of an inch sheet-iron, squared up perfectly true and flat, and cut out as shown inFig. 21, commencing four inches and a half fromA, and leaving six inches atB, and cutting it six inches wide there by eight inches long, and continuing it four inches wide for the rest of the distance. Be careful to keep it quite central on the lineA B, and leave two connecting strips one inch wide, as atC C.
model locomotiveFig. 22.
Fig. 22.
The side-frames come next. These must be much stronger, and quite different from those used in our previous model, and should be cut from the same eighth of an inch plate-iron to the shape shown inFig. 22.
The centre of slotBis seventeen inches from one end, the centre ofAten inches fromB, and centre ofCthirteen inches fromB.
In marking out work always measure from a fixed centre, for if you add onemeasurement to another any slight inaccuracy gets increased with each fresh measurement, and you might finally get the different portions out of place.
The slots are each an inch and a quarter wide by two inches deep, leaving one inch of iron at top as shown. The ornamental spaces can then be cut out, which lightens it considerably without weakening it much.
The frames, after being smoothed up, can be fastened to the bed-plate in the manner described before by angle-irons or knees riveted on. Two end-pieces must also be prepared an inch deep, and the ends hammered square at right angles, and then riveted to the bed-plate and side-frames, as shown by the rivets inFig. 20.
Then drill three holes in them about an inch and a half from either end, and one in centre by which to bolt on the buffer-beams by means of a couple of screws put in from the back.
model locomotiveFig. 23.
Fig. 23.
The buffer-beams should be mahogany, one inch wide, two inches deep, and ten inches long, squared nicely and sand-papered. A hook can then be made (Fig. 23), and, a hole being drilled in the centre of beam, you can pass the hook-stem through and into central hole of framework, and screw up tightly with nut at back, which will hold all firmly in place.
The buffers for this model must be made properly with springs to take the pressure, should you let it run into anything.
model locomotiveFig. 24.
Fig. 24.
Turn out a wooden mould in the lathe and get four castings in brass made from it.Fig. 24is an ordinary kind of buffer in general use, and, being in section, shows you the working arrangement of the spring,Ais cast with a square base-plate two inches square, as in front viewB, and is secured to buffer-beam by four flat-headed screws. The pieceCmust be turned true, and just the size to slide in and outAeasily. Each part must be finished up in the lathe.Ashould be about an inch and a half long.
Drill a hole in beam to allow the head of pin to work in freely, and another hole in base-plate of buffer the size of pin, whose head prevents the spring forcingCentirely away fromA.
The spring should be made of thick steel wire; the buffers can then be screwed on as just mentioned. The wheel-guard, or line-clearerP(Fig. 20), can next be cut out to shape and bolted on to frame, and should just clear the line by a quarter of an inch.
We will now proceed with the axle-bearings and springsU(Fig. 20). The wheels can be finished up in the same manner as previously described, so I need not say anything further about them.
model locomotiveFig. 25.
Fig. 25.
Make a wooden model likeFig. 25and get six castings in brass made from it. They then must be filed up square and smooth and fitted into the slots cut atA B C(Fig. 22), and either screwed or riveted on by the side holes.
Before finally fixing them prepare six brass bearings (B,Fig. 25). They must fit exactly, and slide easily in the inner surface ofA, and a hole is to be drilled centrally through each five-eighths of an inch in diameter. These take the axles, which in this model are all straight, and three-quarters of an inch in diameter, shouldered off to five-eighths for the bearings.
model locomotiveFig. 26.
Fig. 26.
The springs next require attention. Four pieces of either sheet iron or brass are wanted in each support an inch and a half long by a quarter wide. A hole is to be drilled at either end, as shown atCinFig. 26.Ashould be three-eighths of an inch wide, drilled through and a pin put in, and all riveted together loosely.
The spring is best made from clock-spring, and cut to shape as atD. The top-piece requires to be made hot with your blowpipe, and then the ends turned over to hold the pinB. Each piece of spring must be slightly shorter than the upper, and the ends nicely graduated off, and when ready held together by the brass bandF, which has a small hole drilled atFto hold the end of pin by which the pressure is directed on to the axle-boxes, as shown inFig. 20. A hole is also to be drilled in bed-plate over centre of each axle-box to allow pin to pass through, and also a smaller one an inch and a half on each side for the supportA(Fig. 26) to screw into. They can all be fitted into position.
model locomotiveFig. 27.
Fig. 27.
The cylinders come next, and should be, as previously mentioned, an inch and three-quarters bore by two and a half inch stroke. These should be of the fixed slide-valve pattern, with double eccentrics fitted on middle axle-shaft, and reversing-lever brought to quadrant on foot-plate, as I will show presently, and for the method of making them I will again refer you to my article on theModel Launch Engine, and will simply give you inFig. 27the modified form necessary to suit a locomotive, inwhichA Aare the eccentrics,Bslide valve-rod, with guideGattached;C Cthe bed-plate,Dthe balance-weight, andFthe rod leading to quadrant and lever on foot-plate. The cranks are put on outside the wheels and fastened by keys, as inFig. 20.
model locomotiveFig. 28.
Fig. 28.
The connecting rodsTshould be cut to the form shown inFig. 28, and the ends squared out and a brass bush filled in with a hole drilled from top (A) to oil by, and a set-screwBfitted to adjust the bearings perfectly.
Although these little things give extra work in fitting a model, they add considerably to its finish and lessen the friction.
If you wish to fit a force-pump, it should be placed centrally between the cylinders, and be worked by an eccentric on main shaft, but a pump on a model locomotive is of very slight use unless it is arranged to work by hand also.
model locomotiveFig. 29.
Fig. 29.
InFig. 29I have given a practical method of arranging one to be worked either way as desired.Ais the pump,Bthe eccentric on main-shaft to work it by steam power; but when requiring to work the pump by hand, you have only to push up hook connection atC, which disconnects it from eccentric, and then by working the handleD, which is screwed into bottom of plungerC, the water is forced into boiler.
This pump is a little more troublesome to make, as it requires an extra stuffing-box atF, but it is very neat and useful, and the handle lying quite out of the way, does not spoil the appearance of the model.
Gis the exhaust water-pipe bent up to the back pressure-valve on boiler, andHthe supply-pipe carried on to rear of engine.
You will find two small blow-off cocks on each cylinder very handy to get rid of the condensed steam when starting the engine with cold cylinders, as without them the cylinders get choked, and you stand a good chance of getting scalded by the hot water being thrown up the chimney with considerable force.
The blow-off cocks can be connected with a tye-rod, and both worked from the foot-plate by a single handle.
The parts being all finished to your satisfaction, you should paint the bed-plate black, and side frames red, and when dry carefully line them black and white, and also pick out the rivets with black.
Of course individual taste has a great deal to do with the finish of a model, so I will leave it to you, merely suggesting you should get a fine lining tool to finish with, and when all is complete put it aside to dry whilst we proceed to build the boiler.
This will require the greatest care, but with due attention you will be able to turn it out well. Some sheet copper will be required one-eighth of an inch thick, and although this is more expensive than iron, it does not rust, and is more suitable for the work in hand.