Martin Evans introduces a new ME locomotive, a scale model in

7\ in. gauge of Sir William Stamer's renowned LMS Black Five

MODEL ENGINEER I January 1965

W H I L E my proposal to describe a modern 4-6-0 locomotive for i\ in. gauge has been welcomed by many, a few voices have been raised in protest. It is said that no-one can afford to build such a big engine, that hardly any live steamers have equipment large enough to tackle the job, that there is no interest in this large scale, and all that readers want is simple constructional information—how to build a si m-gauge 0-4-0 tank engine.

First, I would like to remind these readers that ME has never, in its 66 years' history, described in full a 7? in. gauge locomotive, apart from the Midge, which, although an ex­cellent little engine, was only a 0-4-0 dock shunter. I have had many enquiries, especially from overseas readers, for a constructional serial in ii in . scale. As my correspondents rightly point out, there are very few sets of working drawings for this scale on the market, and these are all early Henry Greenly designs. While I have the highest regard for Greenly's work, I think all readers wi l l agree that we have learnt a little more about model locomotive design during the last thirty years or so, and that Greenly's designs are not quite up to the standard of 1964.

Even if my readers cannot afford to build a q\ in . engine, or have no wish to do so anyway, I still hope that they wi l l find something of interest in the serial. I shall be describing the locomotive once a month. My series on locomotive practice wi l l continue to be devoted to hints for the beginner, leading up to a very simple 0-6-0 tank engine designed especially with the tyro in mind.

Let us now have a look at our new engine. W h y call her (or him) Highlander ? Wel l , I must confess that I am not altogether happy about this sex question, as we have always been accustomed to regard a locomotive as a feminine animal, what with petticoats and stays and such-like fittings ! In fact I am simply using a shortened form of the actual name given to one of the class—No 5157 The Glasgow Highlander.

Wil l iam Stanier, designer of the Black Fives, was appointed chief mechanical engineer of the L M S on I January 1932. He was born in 1876, the son of W. H. Stanier, chief stores superintendent of the Great Western Railway. At the age of sixteen he entered Swindon Works as an apprentice. He became a draughtsman in 1897 and three years later was appointed inspector of purchased material. In 1901 he be­came technical inspector in the running department. There­after his rise at Swindon was rapid, and by 1923, when the famous Castles first appeared, he had become principal assistant to Collett. He was thus a leading member of the team which took the Great Western so brilliantly into the " grouping era."

New appointment

As he was only five years younger than Collett, there was not very much chance of Stanier reaching the top on the G W R . When Sir Josiah Stamp, the chairman of the London M i d l a n d and Scottish Railway, offered him the position of C M E he accepted promptly.

In 1932 there were seventy of the efficient Royal Scot en­gines at work on the L M S , but this number was almost lost against the requirements of such a large railway system. There was also a grave shortage of efficient mixed-traffic engines. Stanier therefore had to move quickly. While his first designs were being prepared, further engines of the successful three-cylinder Patriot type were completed.

Seven new locomotive designs were put in hand by him. The first to appear were the Pacifies and the 2-6-0 mixed-traffic engines of class 5P4F. These were soon followed by a three-cylinder 4-6-0 express engine, class 5 X P , a two-cylinder 4-6-0 mixed-traffic, class 5P5F, a 2-6-2 tank, a 2-6-4 t a n k and a 2-8-0 freight tender locomotive.

Not surprisingly, Stanier's engines bore a strong resem­blance to Swindon's. While working on his new designs, he had in fact visited Churchward, for whom he had a great admiration. Churchward, though retired, was still l iving at Swindon.

The Churchward boiler appeared on both the new 4-6-0 designs, as well as on the 2-8-0, the M o g u l , and the passenger tank engines. The barrel was tapered. T o p feed was used, and the perforated pipe steam collector was employed at first, to be abandoned later. The only major difference was in the outside valve gear, as Stanier rightly felt that inside gears were too inaccessible for his purpose.

Superheaters

Originally Stanier's boilers had small superheaters: the idea was that the steam was to be superheated just enough to get the best out of the steam actually used in the cylinders, with as little waste as possible in the exhaust. But with the lower quality of the fuels on the L M S system, steaming at first was not too good. Larger superheaters were then tried, and were eventually fitted to all the Stanier engines.

The 5P5F class, the original for my model, was a great success from the outset. M a n y consider the design to be the best mixed-traffic engine ever produced in Britain. Yet strange to say, the Black Fives, as they became known, did not do too well in the great locomotive exchanges of 1948. Perhaps the drivers concerned were too pre-occupied in trying to keep down the consumption of fuel. At all events the average performances were well below what everyone expected.

As first built the Black Fives had two outside cylinders i8t j in . X 28 in . stroke and piston valves 10 in . dia. driven by Walschaerts valve gear with a maximum travel of 6J in. Driv ing and coupled wheels were 6 ft dia. and the bogie wheels 3 ft 3i in . The boiler had a tube heating surface of 1,460 sq. ft, and the firebox of 156. Superheater heating surface was 227.5 sq. ft, grate area 27.8 sq. ft, and the work­ing pressure 225 p.s.i. The tractive effort amounted to the useful figure of 25,455 lb.

In later engines the firebox heating surface was increased to 171 sq. ft, and the superheater to 348. Grate area became 28.65. During the last few years of the existence of the L M S , many of the engines were fitted with self-cleaning smoke-boxes, rocking grates, and self-emptying ashpans.

In spite of the wheel diameter, and the rather long-stroke cylinders, the Class Five engines were fast. A few years ago, No 45336 was limed over the 46.7 miles between Bletchley and Euston in 41I minutes, hauling 220 tons. The maximum speed was 884 m.p.h. at Wembley.

This was no isolated performance, for many times I have stood on one of the platforms at Willesden Junction, and seen a Class Five hurtle through at a speed of about eighty, the driving wheels spinning round at a fantastic rate and the motion almost a blur.

Highlander has been drawn almost to scale. I wonder if any Crewe enthusiast wi l l be able to spot where I have de­parted very slightly from the exact dimensions. Yes ! The bogie wheelbase is just a little over the L M S figure of 6 ft

Continued on page 38

Highlander . . .

Continued from page 20

6 in. , while the distance from the vertical centre-line of the cylinders to the leading coupled axle has also been increased very slightly. I have made these alterations purely to allow more clearance for the bogie wheels on sharp curves. A l ­though the result is to make the whole engine a little longer, I do not think that anyone wi l l quarrel with the general pro­portions.

The cylinders of the model wi l l be approximately to scale— 2J in . bore X 3i in . stroke. The piston valves wi l l be i j in. dia. and the steam ports A in . wide. F u l l gear valve travel wi l l be i in . , the lap a7z in . , and the lead 0 . 0 2 0 in .

A few other dimensions may also be interesting at this stage. The mainframes are cut from A in . thick bright mi ld steel, and their maximum width is 6i in . T w o lengths just under 5 ft long wi l l be required. To keep down expense as much as possible, many of the frame stretchers and the valve gear supports wi l l be of built-up construction, though cast­ings wi l l be needed for the motion plates, and for such things as main horns, main and bogie axleboxes, cylinders and valve liners, saddle, chimney, dome, top feed cover, and so forth. These wi l l all be obtainable when required. Full-size draw­ings wi l l be offered, as usual, though the general arrangement wi l l be supplied at half full-size.

To be continued

HIGHLANDER A 7\ i n c n Sauge model of the Stanier Class Five 4-6-0

B E F O R E we have a look at the mainframes of the Stanier 4-6-0, perhaps a few words on the problem of handling a large ii in . scale locomotive wi l l not be unacceptable.

A few years ago, I was faced with the problem of over­hauling three i\ in . gauge engines. One was a L N W R George^the-Fifth 4-4-0, and the others were L S W R 4-4-os, rather lightly built compared with the North Western engine. Fortunately I had plenty of bench space. My main difficulty was to lift the engines on to the bench from floor level, work­ing entirely single-handed. They had arrived on a short length of track, having been brought to my workshop in a shooting-brake.

I had no proper lifting tackle, and I was loath to waste valuable time making such equipment, which was unlikely to be much use to me after the engines had been finished. As I was just strong enough to lift one end at a time of even the heaviest engine, I gathered together a number of old wooden crates and boxes, mainly between 10 and 14 in . high, and wide enough to take one end. After stiffening them up internally with scrap wood and nails, I slewed the locomotive round unti l it was parallel with my bench though just below it. By lifting one end at a time, I was able to jack up the engine gradually, one box height at a time, until I had it just a few inches higher than the top of the bench. A l l that I then had to do was to slew the engine across.

But for a large 4-6-0, this makeshift arrangement is not good enough; and as the weight problem wi l l make itself felt as soon as the mainframes, buffer beams and stretchers have been fitted together, some provision for easy handling of the model should be made.

Mr H. A. Taylor of Bletchley, who is building a very fine model of the Black Five to § in . scale, has solved the problem completely. He has designed and built what one might call, for want of a better description, a rotating erecting stand. Briefly, it consists of a strong base made of wood, steel flats, or steel angles, about a foot longer than the overall length of the engine. On strong uprights at each end are stout pivots, on a horizontal axis, with clamping nuts and washers—I think about i in . B S F . Triangular hardwood plates are then arranged, with holes to match the buffer fixing holes in the buffer beams, in such a way that the whole locomotive can be suspended from the pivots. By arranging the point of attach­ment of the beams so that the pivots are approximately at

Beginning on

the mainframes Continued from January 1 bjf M c t r t i n EVcHIS

the centre of gravity (guess-work at this stage) the engine can be revolved by hand without strain, as soon as the clamp­ing nuts at each end have been slightly slackened.

An erecting stand of this sort would be a tremendous boon in the building of a big heavy engine like Highlander. The base could be formed from two 6 ft 6 in . lengths of steel angle, about ii in. X i i in . X A in. , and the uprights at each end could be made from similar material. As a refinement, the pivot at one end of the stand might be fitted with a strong worm wheel and a worm shaft and handwheel be provided so that the locomotive could be turned as required, with no effort at a l l ; the pivot at the opposite end to the worm gear should of course have a strong clamping nut and washer, which would have to be slackened off each time that the turning wheel was used. While an elaborate assembly stand like this might take some time to make, in the long run it would save time, besides making the construction of the locomotive itself much more pleasant. It could be made adjustable for length, or even for engines of different scales, through the use of end plates and pivots to suit the standard buffer and drag beams of the different scales. The pivots must be high enough, so that when the finished locomotive is revolved, the outer top corners of the cab, or whatever part protrudes the most, does not foul the base members of the stand.

If any readers would like further details or a drawing of a suitable assembly stand, I wi l l be pleased to help.

The mainframes of Highlander are cut from A in . thick bright mi ld steel. There is no alternative material, as I do not think that even the most enthusiastic builder would contemplate making frames of this size from stainless steel !

No 5024. One of the early batch of Black Fives

We shall need two lengths—6k in . wide and 5 5 ! in . long. Originally I hoped that the frames could be made from 6 i n . wide material, but this proved too narrow. As the com­mercial 6 i n . width is very often a shade under six inches, and the edges are seldom true and square enough to be used with­out considerable cleaning up, cutting the frames from the next size wider could not be avoided. If you have the material cut by guillotine, do not forget to allow extra on the width, so that you can obtain a nice square edge by sawing.

Those who have not built in this scale before may wonder how they are to make the edges straight and true. Very, very few wi l l have a surface plate or a lathe bed as long as five feet ! Instead of truing from first principles, a method that takes an awfully long time, we may consider the o ld plate-glass dodge. The thick plate glass used for modern shop doors and so forth is true enough for our purpose. We shall need a piece 5 ft 6 in . long by at least 18 in . and preferably 24 in . wide. The extra width is very useful during the later stages of construction, when we may require a surface gauge for checking the boiler level or a similar operation. Take care

not to break the glass: there should not be much danger of this when the mainframes are placed on it, but I would not feel too happy about lowering the locomotive on its wheels. 1 think that some protecting material, such as true strips of hardwood, wi l l have to be placed under each wheel flange.

N o w let us have a look at some of the holes that wi l l be required in the mainframes. Needless to say, a i i n . capacity motorised dril l ing machine is almost essential in this scale. Something rigid in the way of side supports must be set up on the bench at each side of the dril l ing machine table, to prevent the frames from getting out of control when we are dri l l ing towards either end. I find these supports a necessity in 5 in . gauge work too.

Starting from the left-hand end of the frames, we first have a group of eight A in . dia. holes for fixing the frames to the buffer beam angles. The angles wi l l be castings, with proper ribbing, or they may be built up from bright m i l d steel sections by brazing or welding. Proper hexagon-head 2 BA bolts should be used.

Just above this group we have the lifting hole, which is

f in . dia. and is reinforced on the back with a steel disc of the same thickness as the frame—this should be done later, when the frames are ready for assembly.

M o v i n g a little to the right, we see another group of eight holes, in the shape of a reversed letter L. These are for the front frame stretcher (Stretcher A ) . We then come to the cylinder fixing group—14 holes to be reamed i in . dia., to­gether with two large holes which are to clear the exhaust pipes from the valve chests. Immediately above this, we have a long row of No 27 holes, for securing the saddle to the frames. The reason for the gap between the two on the left and the other nine is simply that in the missing locations it would be difficult to reach the screw heads unless the cylinders were first removed. It is expecting much of a modeller's patience if he has to take the cylinders off, with all their connections, in order to fit the saddle !

The I i n . dia. reamed hole at the right-hand end of the last group is to carry the cross-shaft for the operation of the cylinder drain cocks. I always make the drain cock operating gear quite substantial, as it is in fairly constant use.

To carry the bogie stretcher, we have a row of A i n . dia. holes along the bottom edge of the mainframes between the bogie wheel arches. The A in . dia. reamed hole is to carry the cross-shaft which operates the drain cocks, as in my Springbok design.

M o v i n g further again to the right, we come to the location of the main frame stretchers B, with a row of six A i n . dia. holes. No holes are shown on the remaining part of this stretcher because the outside motion plates lie here; in fitting them, we can use hexagon-head screws into tapped holes, which can be made right through the frames and into the stretchers. There are also A i n . dia. holes to locate the positions of the brake hanger brackets, which are 5A in . ahead of their axle centres and 13 in . above the bottom edge of the frames.

The position of the J in . dia. hole which carries the weigh-shaft should be set out with care, and so should the A i n . lining-up hole to the left of it—the centre of the expansion link pivot. To the right of these holes, we have another large

Continued on page 100

HIGHLANDER . . . Continued from page 97

group to carry the vertical stretcher C, and further to the right another group of eight holes, some of which have to be countersunk on the outside, to carry stretcher D. These holes have to be countersunk owing to the proximity of the coupled wheel flanges. There would be just enough clear­ance for hexagon-head bolts if the engine were traversing dead level track, but with a slight rock the backs of the flanges would be scraping.

Just to the rear of the trailing coupled horn is a single A in . dia. hole for a simple round stretcher, which wi l l be useful to stiffen the frames at this point—rather a distance from the nearest main stretcher and the drag beam attach­ment.

Along the top of the rear end of the left-hand frame, we have a group of ten A in . holes which are to carry the support for the cab reversing gear. In the full-sized engine the sup­port is built up on the footplate, but I do not recommend our copying this arrangement. It is much easier to mount the whole of the reversing gear directly on the mainframes, and the effect is much stronger. This is one of those instances where it pays to depart from the original, even if we are building a 15 in. gauge engine ! We need not worry about the reversing gear fouling the boiler. The reach rod passes very close to the left-hand side of the firebox, but the whole of the cab reversing gear lies to the rear of it.

We shall also require two further A i n . dia. holes in the right-hand frame only. They lie at 2§ in . and 3 in. from the extreme rear end of the frames. They are for the levers which operate the cylinder drain cocks and the damper doors.

Finally, we have another group to carry the drag beam fixing angles, and along the bottom edge a row to support the steam brake cross-shaft.

To be continued

HIGHLANDER A 7i inch gauge model of the Stanier Class Five 4-6-0

T H E front buffer beam of Highlander is cut from i i n . bright mi ld steel. After sawing off the required length, mark out the vertical centre line, and the horizontal line through the buffers and coupling slot, which in this engine is not in the middle of the beam. D r i l l the buffer holes. To shape the coupling slot dr i l l a hole slightly smaller in diameter than the width of the slot, and then insert a stout metal fretsaw blade and cut out, afterwards finishing with a square file.

Y o u should also dri l l the hole for the vacuum brake pipe. It is i in . dia. and is situated A in . below the top edge of the beam and i A i n . to the left of the coupling slot. Even if working vacuum brakes are not to be fitted, an engine looks very bare without a dum­my brake pipe.

On the back of the beam, mark out the location of the mainframes. The fixing angles are iron castings. If you prefer to use built-up angles, check that they are square after the brazing or welding. After cleaning the castings with files, machine them on the two bolting faces to be sure that they are exactly at 90 deg. Y o u can clamp the casting down under the lathe toolholder and flycut one face at a time. This method should be quite accurate if care is taken on the second set-up.

When the four fixing angles are ready for assembly, place them in position on the back of the buffer beam, and use an odd piece of the steel which you obtained for the mainframes as a gauge, to get the two pairs at the right spacing and the right distance from each other.

/ should remind American builders, who want their engine to run on i\ in. gauge track, that they will have to set their frames further apart. They should space the frames 6A in . , J in. more than for the British 7} in . gauge, and they should also note that their buffer and drag beams must be the same amount longer overall. If they imagine that the model is split right down the longitud­inal centre-line, and that J in. of " what­ever is there" is added to the British dimensions, they wi l l not go far wrong!

N o w run a dri l l through the holes in the fixing angles into the upper beam and temporarily bolt the inner angles only to the beam, using 5 BA screws. R u n a A in . dia. dri l l through the holes

STRETCHERS-

FABRICATED

OR CAST ?

Continued from March 1

by Martin Evans

No 45106 at Leeds, show­ing buffer beam details

in the mainframes, which are offered up in turn, in the correct position. Make deep countersinks in the inner angles. Remove the angles and dri l l out A in . dia.

The inner angle on one side only is screwed to the buffer beam again, the frame is offered up, and the outer fixing angle on that side is lined up and bolted to the beam. R u n the A in . dri l l through from the back, making counter­sinks on the outer fixing angle. Re­move this angle, and dri l l A in . again. Repeat on the other side of the engine.

We can now bolt both fixing angles back in place, checking them with the odd piece of frame steel, and replace the 5 BA screws one by one with i in . iron snaphead rivets, for which the outer face of the buffer beam wil l have to be

countersunk. Clean the face, finishing with emery cloth, so that no trace of the rivets should be seen on the outside. Then we can tackle the drag beam.

The fixing angles for the drag beam are simply short lengths of A i n . thick bright steel angle i i i n . X i | i n . As long as they are really at 90 deg., all we have to do on them is to face the ends accurately, an operation which can be performed in no time at all in the four-jaw. The drag beam itself is cut from k in . thick bright m i l d steel, and shaped at the ends as shown in my drawing. (For ~]\ in . gauge, add i i n . to the overall length.) Cut the engine-tender coupling slot by dril l ing a row of holes and sawing into them with a stout fretsaw blade, or with an abrafile. Finish it with files.

T h e fixing angles are positioned and riveted to the drag beam in exactly the same way as the buffer beam. When they are all fitted, the two flat plates upon which the tender buffers bear are fixed on the back face, with a long i in. rivet in each corner. Finally, we need the two pieces or angle to form the dragplate, mounted just above and be­low the coupling slot, and the short lengths of brass angle, which are riveted to the top inner edges of the beam, to carry the rear ends of the footplates.

We now come to the frame stretchers. I have designed them to resemble the full-size fittings which are all built up without castings. While everyone may

choose between castings or a built-up construction, the largest stretcher—the one which I describe as the main stretcher B—I am showing as a built-up component. T h i s is the most important stretcher of them all, as it lies between the cylinders and the driving axle. W i t h either method, the bolting faces should be carefully faced to the exact length required.

It may be thought that to set up these big stretchers on a lathe of moderate capacity will be a problem. F o r myself, I should remove the top-slide, and clamp the stretcher down to the cross-slide, using long bolts or studs threaded

Continued on page 226

HIGHLANDER Continued from page 213

about I i n . and flat steel bars about 1 i n . X f i n . section. The stretchers would be raised by sufficient packing, and the face to be machined would be set out with sufficient over­hang for a flycutter to sweep the required area. I should then put on the cut by advancing the leadscrew handwheel. The main stretcher B would, of course, need packing 1A i n . thick to set it on an even keel.

Where castings are preferred, cast iron is really the only metal worth considering. Gunmetal would make good cast­ings, but its cost for such heavy parts would be prohibitive. The top and bottom edges could be cleaned with files, and so could the openings. The only essential machining would be the facing of the bolting surfaces. As it is extremely i m ­portant, when we reverse the casting on the cross-slide, to get both faces exactly parallel we use a D T I , or a large vernier caliper, to be sure that the face just machined is maintained parallel to the lathe faceplate, which should be put p n ' f o r this check.

In my next instalment, I shall deal with the remaining frame stretchers. Then we can have a look at some of the running gear, such as axleboxes and horns.

HIGHLANDER A 7i inch gauge model of the Stanier Glass Five 4-6-0

WE now come to the third frame stretcher. Before making it, we should decide whether to fit feed pumps to the engine, or whether to rely solely on injectors. My own view is that the modern injector is sufficiently reliable for us to dispense with pumps altogether. This means that we have no work­ing parts at all between the frames, making maintenance very easy. However accurately axle-driven pumps are made, they always add quite a bit of friction, and unless they are carefully designed and laid out in relation to the main cranks they can cause jerking, especially at low speeds.

Yet my correspondence tells me that many modellers still prefer pumps, though they wi l l fit at least one injector for topping up the boiler during stand-by periods. I have not yet been able to evolve an axle-driven pump that wi l l feed when the engine is stationary !

Those who are doing without pumps should fit two i n ­jectors, one a little larger than the other. Drawings of suit­able injectors wi l l appear towards the end of the serial. In the meantime, note that the frame-stretcher C is made with two oval holes if no pumps are required, or with two slots, open at the bottom, if pumps are to be fitted.

by Martin Evans

Continued from March 15

From the stretchers

to the main horns

and the axleboxes

The stretcher may be an iron casting or built up from mild steel, in which event all that we shall need is a slab of 6 in . X I in . steel and two pieces of if in . X i in . Again, be careful to get the two bolting faces exactly parallel, as well as the right distance apart.

Frame stretcher D lies just above the driving axle and is of very simple con­struction. If you are building it up, you can use four pieces of bright mild steel, all 1 in . thick. The two square holes in the upper outer corners have been put i n , just in case, at a later stage of construction, we find that we must pass some pipes through the stretcher, below the boiler. Readers might think this a somewhat damaging admission, but I freely confess that, at this moment, not all my detail drawings have been completed, and it is better to be safe than sorry !

For the last frame stretcher we have a very simple one, turned from f in . dia. round mild steel. It is secured just to the rear of the trailing coupled horns.

Our next task is to machine the main horn castings. They are a very close copy of the horns fitted to the ful l -

sized engine, and wi l l be obtainable in grey iron from one of our regular ad­vertisers.

H o w we tackle the machining of the horns, and particularly the axlebox working faces, must depend upon our equipment. Probably a large vertical mil l ing machine, such as is found in most professional machine shops, is the ideal tool. The faces of the horns which are riveted to the frames can then be machined in the traditional manner, which I wi l l deal with in a moment. The horns are then riveted

in position, and the frames bolted back-to-back. The pair can now be bolted to the mil l ing machine table, with suit­able packing strips underneath, to allow clearance for the tool. If a standard i in . dia. end m i l l is used, to give suffi­cient depth to machine both frames, a radius of f in. wi l l of course be left in each corner. Although this also could be cut away, using a special long end m i l l of about A in . dia. it is a laborious business, and it is really much easier to finish the corners with files, after the frames have been separated.

If you have no equipment suitable for machining the horns after they are fitted to the frames, it wi l l not be diffi­cult for you to machine the horns com­pletely, and individually, before they are put in . The slots in the frames should of course be filed in pairs, as accurately as possible, with a piece of steel bar used as a gauge.

After a preliminary rough filing of the outsides of the horns, bolt each in turn to the table of the vertical slide, with the face of the horn which wi l l he against the frame towards the chuck.

Clamp a piece of flat steel about i in . X | in . across the flanges by a single central stud about i in. dia. T w o addi­tional clamps wi l l also be required, to hold the casting by its outside while the inside is machined by the end mi l l .

An end mi l l f in . or J in . dia. should be suitable for mil l ing all around the flange, leaving a width of if in. or

whatever fits the exact width of the frames. The dimension can be checked with a micrometer, or a good vernier caliper. As the flanges must protrude at least a72 in. from the face at this stage, it should not be difficult to get the micrometer into position. The first cut can be about 0.050 in. according to the machining allowance left by the pattern­

makers, but the finishing cut should not be more than about 0.008 in . if a good finish is desired.

Without slackening the central stud, put on the two outside clamps and tighten them down. Remove the cen­tral stud. The flanges can then be machined down so that they stand out ft in . from the face. M i l l the inside faces away in a smiliar way, using a gauge for the width of the axleboxes. Note that the thickness of the flanges left must be exactly the same on either side, or the axleboxes wi l l not lie square across the frames. Finish the inner corners by filing after the machine work has been completed. To complete the machining required at this set-up, m i l l the bottom edge to size.

Be sure to remember that with this method for machining horns the axle-boxes must be bored so that the axles lie quite square across the frames. I would strongly recommend the " but­ton " method which I described in January 15 issue (pages 60 and 61).

Some may like to consider the solid mild steel type of axlebox, fitted with one of the graphite-impregnated bushes that are now obtainable. If these are used, it is extremely important that you adhere to the manufacturers' recom­mended interference limits, or the bush wi l l shift under load, with disastrous results. W i t h the i j i n . bore Lubrook bush, you must bore the axlebox to 0.004 in. under the nominal size, to get a sound press fit. Do not forget, too, that in dri l l ing for an oi l box the oi l

Continued on page 255

H I G H L A N D E R Continued from page 249

hole is not drilled right through the bush. Y o u need only introduce the oi l to the outside of the bush to obtain proper lubrication.

But I really prefer the split axlebox, made from phosphor-bronze castings. My drawing gives all the necessary details. We machine the outsides by mil l ing, planing or shaping, according to our equipment, and then slot out the upper part for the jaw of which the keep, undrilled at this stage, is milled to a nice working fit. There must be no signs of shake. The keep is kept in position by two A in . dia. silver steel pins pressed into position from the side of the box. As a safety measure the ends of the pins should be slightly rounded, though they should not be so long that they wi l l rub on the horn working faces. The main cross pin, which carries the spring pins, is of A in . dia. silver steel, and is a press fit in the axlebox on the far side, a light press fit on the nearside, and a working fit for the spring-pin heads.

At this stage, the axleboxes can be bored, as described on January 15, and the recesses for the oiling felt pad be milled out. There is no need to dismantle the axleboxes, as a small Woodruffe cutter can be used. Remove any burrs. The fact that a great deal of the apparent bearing surface has to be removed to carry the oi l pad does not matter a bean: once the weight of the engine is on the wheels, only the top half of the brass is subjected to wear.

We had better machine the spring pins from the solid and not attempt to build them up, as they must be thoroughly sound. Flat b.m.s. bar | in . X | in . is the nearest stock size. So that decent cuts can be taken, use the four-jaw chuck, and support the outer end with the tailstock, cutting off the excess containing the centre after the pin has been turned to the correct diameter, ready for screw-cutting.

Although the axlebox springs can be made in the home workshop, home-made springs never seem quite so good as the professional product. As Terrys made me some very similar springs a short time ago, they should be able to supply what we need at a reasonable cost.

To complete the axlebox-horn assembly, all we require are the hornstays and the spring plates. The stays are properly shaped, so as to stiffen up the frames at their weakest points, and can be cut from I i n . X J in. b.m.s. To prevent slight dimensional errors, the positions of the holes through which the spring pins pass should be checked from the work itself, and the holes should be eased out to about 17/64 in . dia. to allow plenty of freedom to the axleboxes.

To be continued

HIGHLANDER A 7i inch gauge model of the Stanier Class Five 4-6-0

M Y reference t o a locomotive erecting stand, that wi l l allow large and heavy engines to be manhandled with the minimum of effort, has aroused a lot of interett. Several builders who are engaged on big 5 i n . gauge locomotives have come up against the handling problem, and so I thought that a sketch of a suitable stand would be appreciated. The one shown is for i\ in gauge engines. By making the base angles a little longer, and by drilling rows of holes corresponding in pitch to those in one of the end plates—which can be shifted along as required—locomotives of different lengths can be accommo­dated. For 5 i n . gauge models, the

stand could be shorter and the end plates not quite so high. T h e worm gearing at one end is an added refine­ment. To rotate the engine, the plate at the opposite end to the gearing would have to be slackened off and re-tight­ened after rotation.

An erecting stand of this type wi l l amply repay the time spent on its con­struction: it w i l l make assembly of the hundreds of small parts involved

in building a big engine a pleasure. An enthusiast who is making High­

lander with the aid of a lathe no larger than the M y f o r d M L 7 or Super 7, or similar 3J i n . centre machines, wi l l have to seek assistance when he comes to the driving and coupled wheels. If he belongs to a club, it may well be that some fellow member owning a larger lathe wi l l come to the builder's rescue. If anyone is really up against

B A L A N C I N G I S Continued from April 1

by Martin Evans

IMPORTANT it, he should write to me, c/o the M O D E L E N G I N E E R , and I wi l l endeavour

to put h i m in touch with someone able to tackle the job.

M a n y builders of locomotives to 1 J i n . scale fit separate steel tyres to the driving and coupled wheels. Though it is correct practice, I doubt whether the extra work is worth the trouble. Fitt ing separate tyres to cast centres is not an easy operation at the best of times; and there is no objection to the use of a good quality cast iron for the whole wheel. In full-size practice, the wheel centres are almost always steel castings, and the steel used for the tyres is specially rolled, usually from 35-40 ton steel. Balance weights are best made separately and attached to the wheel after turning.

My method of attaching balance weights calls for steel plates, about fa i n . thick, fitted to each side of the wheel hard against the spokes (the front of the spokes may have to be flattened a little by filing.) Screws are put in from the back into tapped holes in the front plate, and filed off flush on the outside. To simulate the rivet heads on the prototype engine, fa in . iron snapheads can be put into the front plate and lightly burred over before the two plates are fitted to the wheel. When the screws are put i n , be careful not to run into one of the rivets, which would rather spoil things.

After the plates are fitted, molten lead is poured into the space between them and around the spokes, unti l it is just below the upper edges of the plates. The amount poured in wi l l be too great for balancing purposes, but the

weight can be adjusted by dril l ing holes in the back of the wheel.

The balancing of locomotives may seem rather a frightening subject to all except skilled mathematicians, but it is surprising what can be done with nothing more than simple mult i ­plication and division, plus some trial and error!

In counterbalancing the reciprocat­ing and revolving parts of a simple two-cylinder locomotive, it is not possible to attain the perfection customary in multi-cylinder petrol-engine design. This is because the locomotive must have its cranks disposed so that self-starting is achieved and a nearly con­tinuous tractive effort obtained.

Problems of balance

T h u s , the cranks of a two-cylinder locomotive are arranged at 90 deg. to one another, and this means that it is impossible to exactly counterbalance reciprocating parts by reciprocating masses, or revolving parts by revolving masses. There are also other difficulties, such as the impossibility of arranging counterbalancing masses in the same plane as the parts being balanced.

It wi l l be seen, therefore, that the balancing of a two-cylinder engine is very much a compromise. If the reci­procating parts, such as the piston and piston rod, the crosshead, and parts of the connecting rod, and so forth, are not even partly balanced, there w i l l be a reaction on the frames of the loco­motive tending to jerk it backwards and forwards. A n d if all the weights of these parts were added together and counterbalanced by extra weight in the driving and coupled wheels, there would be just as much disturbance up and down.

T h e tendency of this extra counter­balancing is to lift the wheels from the

track one moment, and to increase the static load at the opposite point the next. Thus is set up the so-called " hammer blow."

In locomotive work, it is usual to balance the whole of the revolving parts, and a proportion only of the reciprocating parts, generally 50 per cent to 60 per cent. If the reciprocating parts were fully balanced by extra weights in the wheels, the unbalanced horizontal forces, and therefore the swaying couple, would be non-existent, but the variation occurring in pressure on the rail throughout each revolution of the wheels would be great. If, on the other hand, the reciprocating parts were not balanced at all , but the rotating parts were completely balanced, then constant rail pressure would be ob­tained, but the unbalanced horizontal forces and the swaying couple would have dangerous effects at high speeds.

Weigh the parts Coming now to the balancing of

Highlander, the operation should not be attempted unti l all the parts have been made and weighed. The wheels wi l l have been completed, and the inner

Counterbalancing Wheel weight available

Leading coupled i j lb. Dr iv ing 6 lb. Trai l ing coupled ii lb.

and outer plates of the balance weights fitted, but not filled with lead. The axles wi l l have been made and the crankpins fitted, together with the retaining collars. It is hardly necessary to make the eccentric rods at this stage, as it is not possible to decide their exact length, so we can either estimate their weight, or make up a rough dummy rod of correct overall propor­tions to get some idea of the weight.

T h e following parts should now be weighed: piston and piston rod, cross-head, connecting rod, coupling rod, return crank and dummy eccentric rod, drop l ink, anchor link and com­bination lever.

T h e wheels are then pushed on to their axles by hand, using just suffi­cient force to get them on true (they wi l l have to be taken off again later) to their correct 90 deg. setting—as near as can be judged by eye, and the use of a square.

T h e wheels and axles are next mounted on knife edges, and weights added to the crankpins unti l a balance is achieved. After this, the wheels are

dismantled and the balance weight recesses filled with lead, as described previously. They are then remounted on the knife edges and weights added to balance as before.

Let us now take an example, using imaginary figures for the various weights of components.

Weights required on crankpins to balance wheel when filled with lead: Leading coupled (say) . . i i l b Driv ing . . . . . . 6 lb. Trai l ing coupled . . . . i j lb.

Weight of coupling rod 3! lb. Therefore the weight of the coupling

rod on each wheel wi l l be i j lb. Weight of return crank plus (say)

quarter the weight of the eccentric rod, J lb.

Weight of connecting rod, 2 lb. Revolving weight of connecting rod

(say 50 per cent.), 1 lb. Reciprocating part of do. 1 lb. Weight of piston, piston rod, cross-

head, drop link, anchor l ink, plus (say) one-fifth weight of the com­bining lever, 2J lb. Therefore the total reciprocating

weight to be counterbalanced: 60 per cent, of 3J lb. or 2 lb. approx.

Revolving Weight available for weights reciprocating masses

i j lb. J lb. 2f lb. 3 i lb. i j lb. J lb.

From the above table, we see that the total weight available for counter­balancing the reciprocating masses is 3i lb. Yet the weight of the recipro­cating parts to be balanced is only 2 lb. T h i s is quite in order, it simply means that we have to remove a total of i| lb. of lead from the three wheels.

We might feel inclined to remove 0.58 lb. from each wheel, but a better way would be to remove say 0.2 lb. from the driving wheel and 0.38 lb. from the leading wheel. The reason for this is that the leading wheel has the additional function of helping to guide the locomotive on the road, and therefore this wheel should not be made heavier than necessary. Although this method of balancing is somewhat rough and ready, it wi l l be found that the results are highly satisfactory, and the difficult mathematical calculations involved in a more " theoretical" approach are avoided.

A point worthy of mention: when dril l ing the hole or holes in the back of the balance weights, we are faced

Continued on page 343

H I G H L A N D E R . . . Continued from page 326

with the problem of knowing how much material (which wi l l be mainly lead) to dri l l away to make up, say, i lb. We can either catch all the chip-pings (not so easy as it sounds!) and weigh them, or we can determine the weight of the metal removed by calcu­lation.

Drilling balance weights

For instance if a hole | i n . dia. x I i n . deep is drilled out, we have removed approximately 0.1 cu. i n . of lead (not allowing for the fa i n . thick­ness of steel on the outside) and the weight of this is quickly calculated knowing that lead weighs roughly 700 lb. per cu. ft. In dril l ing the leading coupled wheel (or the trailing coupled wheel if this should prove necessary) the hole or holes must be made exactly opposite to the crankpin, so as not to upset the balance, but when dril l ing the driving wheel, we can take the opportunity to make the holes to one side, in the same half as the return crank is situated. T h i s arises because the return crank is roughly 90 deg. out of phase with the main crank, and so w i l l upset the balance to a small degree unless some­thing is done about it.

It wi l l be noticed that the full-size engine has the balance weight on the driving wheel across eight spokes, to one side, and not exactly opposite the crankpin, whereas the balance weight on the coupled wheel is opposite the crankpin. On Highlander, I have shown the weight across seven spokes only, so that unless the drilling is done as described above, the wheel wi l l come out slightly out of balance.

When we are dealing with i j i n . scale models, the type of wheel casting where the spokes are made flat on the back, tapering evenly towards the front of the wheel, is hardly good enough, and I strongly recommend that the correct shape of wheel spoke be ad­opted. Spokes should be well radiused into the wheel r i m ; if no radii are allowed for, the wheel may be sur­prisingly weak, and you cannot afford to take liberties when building an engine of this size and power!

To be continued

HIGHLANDER A 7i inch gauge LMS 4-6-0 Glass Five locomotive

A L T H O U G H , i n my last Highlander article, I discussed the making of the balance weights and the calculations neces­sary for balancing the engine, I d id not say anything about turning the wheels, because most builders of this engine wi l l not be entirely new to wheel turning. For the benefit of newcomers I have prepared these notes of the various oper­ations. They are quite simple and straightforward.

A large self-centring chuck saves time on the first oper­ation—a four-jaw is almost as quick. The faceplate may also be used, the casting, after a good cleaning up with old files, being bolted to it through the spokes. There must be enough clearance between the wheel and the faceplate to allow the boring tool to pass right through without fouling.

At the first set-up, the back of the wheel may be turned and brought to finished size, the axle hole bored and reamed, and the flange rough-turned to bring it concentric.

Crankpins and

coupling rods

It is not necessary to turn the backs of the spokes, even if they are accessible to the lathe tool.

I expect that most constructors w i l l use a carbide-tipped tool. I should not think of using anything else, because it wil l turn the whole set of wheels without needing resharp-ening—a great convenience. Moreover, turning can be done at a greater speed giving a cleaner finish, and if any hard spots are encountered, the carbide w i l l sail through. The high-speed tool would not, except possibly if it were re-sharpened and the wheel turned extremely slowly.

If a reamer is not available for finishing the bores, make a plug gauge beforehand and bore all the wheels unti l it can just be inserted. In any case, a dri l l should only be used to open out the wheel sufficiently for the boring tool to enter.

Before tackling the fronts of the wheels, the tyres and rims, a locating spindle should be made up. I favour one with a taper shank to match the lathe mandrel, so that it can be used more than once. In this case, we shall probably

Continued from May I

by Martin Evans

have to reckon with a N o . 3 or No. 4 Morse taper, but this is all to the good, as the spindle wi l l be much stouter. When a really good fitting taper has been achieved, reverse and turn the remainder down unti l the wheels can just be put on. The length of this parallel must be such that it does not protrude beyond the hub after the wheel has been turned to finished dimensions.

The wheel should now be mounted, with the faceplate in position, and with just sufficient clearance for the flange to be turned. At this set-up, and with wheels of this size, it is not advisable to finish-turn the treads—they should be left about 0.005 in . over size The flange should also be that much thicker, the final skim being taken off after the wheels have been pressed on to the axles. To do this i n ­volves mounting the axles between centres, but it ensures that the wheels come out absolutely true.

Highlander's wheels are too large to be bored for their crankpins on the table of the dril l ing machine. They could, however, be bored on the faceplate of a large lathe, being offset the right amount by a simple gauge. A method which I have seen used with success involves fitting a pin (the exact size required to fit closely the bore of the wheels) to the faceplate at the required distance from the centre of the lathe.

The distance can be found in several ways. F o r instance a micrometer or vernier caliper can be applied over the p in and over the barrel of the tailstock, which is brought up in line with the pin. Then all we have to do is to measure accurately the diameter of the pin and the diameter of the tailstock barrel, and subtract half of each from the total dimension. Of course, the throw of the wheels can be a few thou out, up or down, without causing any trouble, but the throw of each wheel must be exactly equal, a con­dition that is brought about automatically by this method.

The boring operation, to take the crankpins, should also be done to plug gauge, which w i l l save time later on. The crankpins can be made from silver steel, or from m i l d steel case-hardened, which I think is preferable. When case hardening, protect the external threads on the trailing crankpins by putting on a nut. The dril l ing operation, to take the splitpin, should be done before this and the nut hardened separately.

The crankpins must be a good press fit to their wheels, the driving pins being additionally secured by fitting a

silver steel parallel p in , about sV i n . dia. in the back of the wheel, half in the crankpin and half in the wheel. This wi l l ensure that the crankpin does not shift through the stresses and strains of driving Walschaert's valve gear.

Because the balancing of the engine cannot be done unti l many of the motion parts have been completed, the wheels are best put to one side at this stage, and the coupling rods tackled.

Using a jig

Perhaps the most important thing about the coupling rods is to make sure that they are to the right centres; that is why I always recommend making some kind of jig, which can be set from the chassis itself. The type I favour carries three (for a six-coupled engine) bushes fitted to a long flat bar, one bush being rigid, the other two being allowed to slide longitud­inally a few thou each side of the cor­rect nominal position. The bushes are, of course, previously turned carefully to a close fit in the axleboxes, and bored concentrically—in this case per­haps j in . dia.

The axleboxes are assembled in their correct running position in the engine frames and clamped there so that they cannot shift while the jig is offered up. The sliding bushes are moved unti l they fit nicely in their respective axleboxes, and they are then clamped to the bar of the jig.

Even the best of us sometimes find that the centres of the driving and coupled wheels are not exactly the same on both sides of the locomotive. The difference may only amount to a thou or two, but the jig w i l l quickly expose any error. This is one of its great advantages, as after using it, say, on the left-hand side, it can be re-set to match the right-hand side, resulting in rods that fit perfectly.

Shaping the rods

Don't forget that the intermediate joint can affect the centres at the rear of the coupling rods. I always prefer to rough out the two parts of the rods, finish the intermediate joint, and then fit a pin (which need not be hardened at this stage) before using the dril l ing jig. After clamping the jig to the partly-finished rod, dr i l l through the bushes. The holes can be bored out in the lathe to take the brasses.

The heavy job of shaping the coupling rods takes time, even if a hefty mil l ing machine is available. Some builders remove metal from the

406 MODEL ENGINEER I June 1965

front and back first, then shape the rods from top and bottom. I prefer to tackle them the other way round. The two front sections are first laid side by side on the mil l ing machine and clamped down through their bearings (before the brasses are fitted of course). A small diameter " slab " mil l ing cutter, wide enough to cover the two rods together, is used, and it w i l l remove metal down to the required thick­ness at the middle. As the rods are fish-bellied, they w i l l have to be shifted so that the middle is left thicker than the ends close to the bearings. Use a file for blending in the shape.

Flutes

Some of the Class 5 s had fluted coupling rods. My drawing shows the non-fluted variety. If you decide to flute yours, I would advise you to do both sides and not the out­side only—as is done on small models—because of the danger of warping. There is no need to go quite so deep however. A shallow flute looks very satisfactory.

When mil l ing the front and back faces of the coupling rods, to thin them out between the bearings, remember that

I do not think that in this scale a full-size quartering jig is justified; the lathe may well be pressed into service to obtain an accurate result. Turned sleeves should first be made up, a close fit on the leading and training crankpins and of outside diameter exactly that of the driving crank­pins. Each pair of wheels is mounted between centres, and the wheels put on at 90 deg. as near as can be judged by a large square and the surface plate. The wheel on the right-hand side of the lathe is rotated so that its crank lies horizontally.

T u r n up a length of round m i l d steel about 1 i n . dia., to act as a stop. It should be of such a length that when stood on the lathe bed, and the r.h. crankpin (with sleeve if it is a leading or trailing pin) is rested on top of it , the crank is at 90 deg. A l l we now have to do is to locate the crankpin in the left-hand wheel (that nearest the faceplate) so that it is straight up in the air, i.e. immediately above the lathe centre.

There are several ways of doing this. One good method is to make a plate, having a hole bored in it exactly the diameter of the driving crankpins, and fix this rigidly to the faceplate in such a position that the l .h. crankpin can

the rods are not now nearly as strong as was the original bar material. Too heavy a cut should not be applied or the rod w i l l bend. In any case, when turning the rods over for the second operation, strips of metal of the required thickness should be packed underneath the middle of the rod.

In this scale, it is worth while hardening the p in , and using a phosphor-bronze bush for the intermediate joint. The main brasses could also be turned from drawn phosphor-bronze, or one of the many special bearing alloys used. In full-size work, the brasses are always keyed, to prevent their rotating or shifting endwise. I doubt if this is really neces­sary in our model; if the bushes are made reasonably tight in the first place, they should not work loose. If keys are preferred, round silver steel pins about 4 in . dia. would be adequate. They can be put in from the back, half in the rod and half in the bush. The oilboxes are bored out unti l the dr i l l reaches the bush, when a N o . 70 can be put right through. The larger diameter is tapped, and threaded plugs put in as shown. The plugs must not be air-tight, or the oi l wi l l not flow unti l some wear has taken place, and so either dri l l them centrally with a fine hole, or file a shallow groove on one side, enough for air to pass.

Perhaps I should mention the problem of wheel quarter­ing. As is well known, the wheels of a two-cylinder loco­motive must be arranged at 90 deg. to one another. The usual arrangement is for the right-hand wheels to lead. While it is not essential that this angle should be exactly 90 deg.—it may be as much as one degree out on either side with no i l l effects—it is essential that each pair of wheels is exactly the same.

be fed into it, while putting the pair of wheels and axle between centres. The faceplate must be locked so that it cannot move, even by the smallest amount.

N o w look again at the r.h. crankpin. Probably it w i l l not be resting exactly on the steel " stop " on the bed. T r y a feeler between the crankpin and the stop. Let us suppose that we can insert a three thou feeler between the two. A l l we have to do is to start pressing home the first pair of wheels, remove from the lathe and insert the second and third pairs, in turn, and check the position of the r.h. crank­pin relative to the stop on the bed. In this way we can ensure that each pair of wheels is quartered to quite a high degree of accuracy.

Check for accuracy After pressing the second wheel a short distance on its

axle, a re-check should be made, as it is not unknown for a wheel to rotate slightly while being put on its axle.

In conclusion, perhaps I should remind builders once again that the operation of wheel quartering must not be done unti l the engine has been balanced, and the balance weights finished off, as described in my last article on Highlander. Perhaps I should also remind those who are using solid axleboxes that both boxes must be put on the axle before quartering, and also that those who are fitting axle-driven pumps wi l l need their two eccentrics on the appropriate axle.

Obvious you may think! Yet is is surprising how often we are caught napping.

To be continued