Or contact:

Send me an
E-mail at:

E.Stroetinga@
fontys.nl

4-6-0 Royal Scot
gauge:   1
railway:  LMS
butane fired

0-6-2 GER 1003
3.5" gauge
railway: GER
Coal fired

0-4-0 Dacre
gauge:   0/1
railway:  Wales NG
butane fired

 

0-4-2 GWR 14xx class
5" gauge
railway:  GWR
Coal fired

Wagons  (Update)
 

0-6-0 T3
7.25" gauge:  
railway:  Germany KWStE
Coal  fired

Links

Downloads
Drawings
 

This is Part 3 of the Didcot: The platework and details.

Part 1     Part 2     Part 3     Part 4     Extra part 4a

The making of a Great Western Railway 14xx class 0-4-2 tank engine.

I was told that is totally wrong to call these loco’s 14xx. It should be 1400 class, as the 14xx wasn’t railway like…………..this was only done by modellers (especially 00 gauge people use this)…………..However !!!  Click here and be surprised!  This photo was made in the GWR museum at the GWR society at Didcot.  What more proof do you want!

I decided to build number 1414, as numbered on the model drawing, but up to now I have only to be able to find two small photo’s of this particular engine.  It was allocated for most of it working life to Stourbridge.

 These GWR locomotives had many liveries during their existence:

-GWR Brunswick green with letters G W R

-GWR Brunswick green with letters Great Western and emblem in between

-GWR Brunswick green with roundel (shirt button logo)

-BR lined green livery with emblem featuring lion-holding-wheel and words British Railways

-BR plain black with lion-over-wheel emblem

So there is plenty to choose from.  I went for the Brunswick green version , but frames are always black as the bufferbeams are 'signal red'

The model dimensions are: (On scale of   1 : 11.29 )

Width: 229.5 mm  [9 1/32”]

Height: 336.5 mm [13 ¼”]

Length: 806.5  mm  [31 ¾”]

I think it will weigh about 45 Kg  [100lbs]

As I said in part 1, I started with the model locomotive after buying the drawings (RV70), the wheel castings and horns from Reeves. The design for 5" gauge is from H.N. Evans, not to be confused with Martin Evans, because I found that they are not related in any way.

The drawings are also not related. The 5” version is closer to scale than the 7.25” version and the 5” version also differs a lot in constructional design.

Although the copy isn't very good (it is sometimes hard to read), the drawing is fairly good, with lots of general detail. (rivet spacing, correct layout of the buffer beam nuts and bolts, correct mainframes, correct Stephenson locomotive expansions links, plate work detail etc.)

The design by Neville Evans is dated December 1985 and I found it, compared with the drawings by LBSC, to be based on more modern design practice.

Quite different is; for instance, the use of O-rings as gland-packing, a crank-axle built-up with Loctite, a radiant stainless steel super heater, etc.

On the other hand I did wonder why Neville Evans didn’t incorporate cylinder drain cocks and boiler blow down valves. With the aid of some original Swindon works drawings and a set of photographs of the prototype, I should be able to make a model in the 1" scale that looks like the real thing.

The mainframes were made of 3 mm steel plate (BMS), although 1/8” was specified. The difference in thickness won’t matter much I think, and because I didn’t adjust for the frame stretchers, this could give axles a little more side play. However I decided (given the circumstances) to put the wheels on their axles with a back-to-back distance of 4 5/8” instead of 4 11/16”. This allowed in its turn for using thicker flanges.

For holding the frame plates against the buffer beams, I didn’t use the specified steel angles, but instead made use of a completely machined, custom-made stretcher, that fits between the frames and also holds the buffer beam. This method (of which a simplified version is also used on gauge 1 locomotives) makes sure that the frame can be easily erected and will stay straight and parallel from the beginning.

The trailing frame is an addition to the main frames, in order to make it possible to use outside axle boxes. These are of the same construction as used on the 3500 gal GWR tenders. The outside axle boxes were a design feature of the prototype, used to create more space on the foot plate.


The small cab of the engine couldn’t do with the coil-spring solution used on the GWR Panniers. The coil-springs on these engines were fitted above the trailing axle box and stuck up through the cab floor. I presume that on the Pannier engines leaf springs under the axle box couldn’t be used, due to clearance problems with the firebox and ash-pan.

The horn cheeks and axle boxes were built up from brass. Aluminium-bronze bearing bushes were glued into the axle boxes. The lid on the top of the axle box can be opened and is used to oil the bearing. That’s what I like about 5” gauge, compared with the smaller gauges…… it’s possible to incorporate more detail.

The cab is made from 1.5 mm brass sheet metal, the roof from steel.

The safety valve is like the prototype built as two separate valves

The smokebox is fixed on the saddle with only one M6 bolt. This way it is easier to remove the boiler from the frames, when maintenance work on the boiler, the cylinders or valve gear is necessary. (By the way, it is not possible to remove the saddle easily, because the fixing screws fall partly behind the coupled wheels).


The two-throw, built-up crank axle is glued together with Loctite 648 high-strength, heat resistant retainer.

The webs were made first. Four pieces of correctly dimensioned steel bar (according to the drawing two of 25 x 6 x 52 and two of 25 x 8 x 52 mm) were soft soldered together for boring. The holes, for the axle and crank pins, were bored to close tolerances (16 mm +0.01 + 0.02 mm), while holding the webs in the 4-jaw chuck. Once this was done, the four pieces were melted apart, and the ends were rounded off (simply filing them, using filing buttons).

The crank pins were made by cutting off two pieces of 16 mm [5/8”]round silver steel of suitable length, which one buys already ground to H7 tolerance (15.99 mm).

The webs were then glued on the crank pins (with the driving axle already in position, but this was not yet glued). To be sure that it will be a sound and strong joint, one must be sure that all parts are scrupulously clean. I used thinners for cleaning and wore special clean-room gloves (which I got from one of my evening-class students), to make absolutely sure that no grease could get onto the parts when handling them.

When the glue was set, one assembly of webs and crank pin was then glued on the driving axle and this was left to set again. In the meantime I made the eccentrics. The last ‘gluing operation’ could now be tackled. The eccentrics were pushed on the axle and the other assembly of webs and crank pin was glued on the axle, set to 90 degrees with the aid of surface plate and square. (Right hand leading)

After the glue had set and the webs had been pinned (2.5 mm roll pins) the part of the driving axle in between the webs was cut out with a hack saw and filed flush.

The pinning isn’t really necessary, because the calculations I’ve made for the force that this glued connection should be able to withstand, will hopefully never occur in service. But if it ever should come loose, the pin will hold the axle together and damage will be minimised.

Due to the high price of the cylinder set, I decided to use bronze bar instead and build the cylinders from solid.  At the beginning I even considered free cutting chrome steel, which I had, but advice gained by e-mail correspondence had convinced me not to use this. Most of the work was done by the shaping machine, which is capable of giving a smooth surface (especially for the port face). The bore (30 mm) was made on the lathe in a 4-jaw chuck. I was able to arrange for the cylinders to be properly honed at work.


The cylinders and steam chest are sealed with  loctite sealant

According to the drawings, the piston rings would be made of 1/8” square soft graphite packing cord.

With my ‘Mona’ I found that after a few seasons of running, the packing had disappeared from the groove. This was maybe due to the fact that I used loose strings of yarn instead of the square cord (which was hard to obtain at the time) and that the mechanical lubricator failed once, which I noticed too late. Whatever the reason, I decided to use a different solution for the problem.

I turned piston rings from Teflon. The piston rings are U-shaped, with the bottom of the U pressing against the cylinder wall. It is about 0.1 mm bigger in diameter than the cylinder bore. Because the ‘legs’ of the U-shape are thin (approx. 0.8 mm) and the groove diameter of the piston (23.6 mm) is smaller than the inside diameter of the ring (24 mm), some allowance is made for compression of the ring (and swelling of the Teflon). The ring is 2.8 mm wide and fits in a groove in the piston that is 3 mm wide. This kind of piston-ring is also fitted on my 3.5” engine (28.5 mm bore) and is still working perfectly. It seals well and has a minimum of friction.


The mechanical oil pump will take care of the lubrication

For the gland packing I’m using Viton O-rings, as specified on the drawing. However I found that one must not use the dimensions of the grooves, given by the supplier of the O-rings. This would give too tight a fit  (and thus a more rapid wear of the ring). For the maximum of 6 Bar [85 PSI] steam pressure a light fit is more than enough to ensure good sealing. Normally the pressure for which these rings are calculated is up to 200 Bar [2850 PSI]  E.g. the supplier states a compression of the ring of 17% of its original cord diameter of the O-ring. I found that 6% to 8% compression is sufficient. The only thing one should be aware of, is that Viton must never be overheated (I believe something as high as 450 degrees Celsius), because then the material will disintegrate, and the residue is very aggressive to skin and can cause extremely serious burns.

Our Steam Society 'Stoomgroep Zuid' has a club track there, next to some sports fields. It's an all steel (noisy, but charming) elevated 3.5"/5" track, with a turntable and steaming bays. Although it is a good track (266 metres long, kidney shaped, almost level) and open all year, it is unfortunately not used much by members of our society.

In the Netherlands there are several tracks all over the country (Breda, Rotterdam, The Hague, Utrecht, Amsterdam, Leek (Groningen), but all the 3.5” and 5” tracks are elevated. Ground level track is only available for 5” gauge in Tilburg, the Netherlands, this is  a multiple gauge ground level track in Tilburg (3.5”/5”/7.25”).  There are several 7.25” tracks over here and all are, without exception, at ground level. Only in Turnhout (Belgium) there is a 5”/ 7.25” ground level track.

Earlier this year I started painting the frames, wheel and motions.

Now (February 2005) the race is on for making the last back head fittings. These are not on the model drawing of Neville Evans, but the idea comes from the ‘Model Engineer Magazine’.

They are made to the ‘words and music’ of  C. R. Amsbury, which he published in the magazine in 1973 and later developed further and described in 1983 (The GWR  Glenn compound locomotive)

The firing shovel, is a close copy of a real one. Although  it has a longer handle and a bit bigger scale: the fireman hands are not scaled down.

It's made  of 1 mm  thick steelplate, that was beaten of a steel former plate. This is best done, when the steelplate is red hot: so in one hand a hammer, in the other a propane blow torch.
The handle is made of hardwood, just like the prototype.


The Injector Water Control Valve is a so called straight through type. Although available at www.ajreeves.com  for a very reasonable price, I made my own, with metric scewthread Mf 8 x 0.75. The body is made of bronze, the inner valve is made of brass with a Telfon bush. 
The check valves are brass with a stainless steel ball. 

There are two ways of doing things:
The wrong way or the Great Western Way

Part 1     Part 2     Part 3     Part 4

Back to Top

Return to Home page.

Didcot taking shape

1466 at Didcot

Fine scale backhead fittings