"Didcot" a GWR 14xx class loco.
 

Guestbook

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
 

Home


The finished loco.
      From start to finish it took 11 years to complete this model.

 

This is Part 1 of the Didcot: A model steam locomotive on 5" gauge (1:11.3 scale) of the Great Western Railway 0-4-2 14xx class.

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


The real loco 1420 and train at Riverford Bridge (England). This is one of the few survivors of the Great Western Railway 14xx class 0-4-2 tank locomotives (1420, 1442,1450, 1466 are preserved). Introduced by C.B. Collet in 1932 to replace the ageing 517 class tanks, of which the 14xx were updated versions. They were originally numbered in the 48xx series and were fitted for working auto trains. Mainly for use on branch lines, they were also capable of a fair turn of speed. I chose this locomotive for my next project because I saw it in a movie "The Titfield Tunderbold" and liked the appearance of these tiny engines. I started out with the 7 1/4" gauge version 'Dart', designed by Martin Evans and serialised in ME, but I found it was too big to handle and to make with my workshop equipment. So I ordered the catalogue of Reeves (England) and found there was also a 5" gauge version.



I started with the model locomotive in January 1996, after buying the drawings (RV 70 'Didcot') and the wheel castings from Reeves. The design for 5" gauge is from H.N. Evans, and although the copy isn't very good (sometimes hard to read), the drawing is fairly good, with lots of general detail. With the aid of a set of original Swindon work drawings, I should be able to make a close copy of the real thing in the 1" scale.


The wheel casting of one of the driver/coupled wheels as they came from Reeves (England). Posting and packing costs are very expensive, so I try to minimise the use of castings. Alas the bosses are to big (according to the prototype), but that is hard to alter now. The cast iron of the wheels is of a good quality and easy to machine.


Milling the horn blocks in the frames. My old (1948) American Van Norman no.6 milling machine is put to use for milling the horn block castings. The blocks are riveted in the frames with 2 mm steel rivets. Not original GWR, but very sturdy. To prevent oil from getting between the horn blocks and the frame (which is very inconvenient during painting) the horns were first fixed with glue (Loctite), but a thick coat of wet paint before assembly will also do.


The cutting of three groves with a saw cutter for the horn cheeks of the trailing axle. A small piece of scrap metal was used to make a fixture for holding the cheeks (brass angle) in the correct position during cutting the slots. In these slots some small webs were inserted and soldered. Only two small tool clamps were used to actually hold them down during the milling process. The large saw cutter was used at a slow speed.


The trailing frame of the little 0-4-2 engine. The horn cheeks and axle boxes were built up from brass. Aluminium-bronze bearing bushes are glued in to the axle boxes. I still have to solve the problem how to make the working leaf springs. The two small boxes on the rear are battery boxes, which were used (on the prototype) to power the ATC (=Automatic Train Control).


Shaping the block for making the smokebox saddle. It takes up some time, but it's nice to watch the shaping machine at work and it is of course capable of taking large cuts at a time. Usually I use some suitable scrap metal for making these parts.


Boring out the smokebox saddle on the milling machine. It was first shaped from solid (again avoiding the casting, due to the high price of importing). The radius (for taking up the drum type smokebox) was also first roughly shaped in form, before turning to the boring head. This saves a lot of time, because the boring head can’t take large cuts.


Glueing the crank axle on the wheels, set at 90 degree angle. For this procedure I used ACAD to calculate the height of two pillars, which in their turn make sure that the crank pins are set at 90 degrees and (more important) that both wheel sets are exactly the same. It worked out perfectly, with no adjustments needed on the coupling rods. The set-up for glueing is made on a machine table (an old spare from a shaping machine), which ensures that the wheels (of which the flanges fall partly in the T-slot of the table) are in line and don't roll away during the setting of the glue (Araldite).


Forming the chimney on the smokebox, using a large bolt to press (and hold) it down on the smokebox. It was turned from solid steel. The bottom flange of the chimney was turned very thin (approx. 1 mm) and was ‘squeezed’ on the smokebox until most of the circumference was in contact with the smokebox drum. The bolt hold it in place, when I was beating down the last part of the flange with the aid of a steel hammer and a brass rod (about 1" in diameter). No heating up was required.


The cylinder block under construction, made from solid bronze bar. Due to high price of the cylinder set, I decided to use bronze bar instead. (At the beginning I even considered free cutting chrome steel, which I had, but by e-mail correspondence I got convinced not to use this). Most of the work was done by the shaping machine, which is able to get a smooth surface (especially for the port face). The bore (30 mm) was made on the lathe in a 4-jaw chuck. I am thinking of using O-rings for the piston rings.


Firebox plate on the former during the beating process. Two steel former plates are used to hold the plate in place in the vice, during the beating (done with a Nylon hammer). The former plates are made of 10 mm thick steel. The copper plates are 3 mm thick. I understand that for 5" gauge it will be a small boiler with an even smaller firebox. The flanges were made to length, after they were formed. In this case the blanks can be roughly cut to shape, when starting with fabrication of the plates.


The plates in a temporary fire hearth for annealing. Heating up was done by a large Sievert propane torch. The annealing was repeated three to four times, to get the final shape. The annealing itself is nothing more than heating up to bright red and let it cool down again. This softens the copper, so it won’t ‘crack’ during the forming process. The fire hearth itself is not much more than a couple of firebricks temporarily placed together.


The throat plate after forming from 3 mm thick copper plate. The ring for taking up the boiler barrel was formed first in a steel ring. A disk on the former plate (with an outside dimension, the same as the inside diameter of the ring in the copper plate) held the throat plate in position during the beating of the outer flange. With this method everything will be nicely lined up during assembly and the connection between boiler barrel and throat plate will be strong.


The model loco as it was at our 'open day' at Breda in June 1997 (the Netherlands), with an GWR 45xx class Firefly. You'll see there is still a lot of work before she will go.


Myself and the loco frame at our annual steam meeting June 1997 in Breda. Driving my 3 1/2" 'Mona' took up a great deal of the day. But there was still time to take this photo. Our Steam Society 'Stoomgroep Zuid' has a club track in Breda, next to some sport fields. It's an all steel (noisy, but charming) elevated 5"/3.5" 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 alas not much used by members of our society.


Another look of the locomotive at a show in Turnhout (Belgium). Here they have a large 5" and 7 ¼" gauge ground level track trough a large part of a park.


The model locomotive as it was November 1997. The frame is on its wheels (not yet sprung) and the brake gear is partly completed. This took up much time, because the ordered brake hanger castings weren't very good. I tried to make them look better (rough casting, out of line and too large) but this wasn't satisfactory. So I've made new ones, building them up from steel plate and some bushes. The cylinders are already fixed between the frames. Due to building a home extension, there wasn't much time for model engineering in 1997.

 

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.

 


GWR 14xx class loco


The  GWR 14xx class loco on 5" gauge  and gauge 1  Royal Scot  class loco at our anual Model Engineer Exhibiton at Raamsdonkveer  14 March 2004

Photo by Rob van Vught 

 

Loco in the Garden


1414 On the track at Breda,
june 2005


1414 On  ground level track,
Tilburg SMMB september 2005


This new ground level track was officialy opened on 9 september 2005 in Tilburg. The Model engineering society SMMB (Stoom Modelbouw Midden Brabant) now has a combined 3.5", 5", 7.25" track and a raised 3.5" and 5" gauge track.