Live steam model on 7¼" gauge of the Württembergische T3 no 924

Welcome to this blog. It will inform you about the progress of designing and building miniature live steam, coal fired locomotives for passenger hauling. Currently I'm working on a 7¼" gauge, scale 1:8, German T3 steam locomotive.

In 2006 I started this new project. This is a small 0-6-0 branch line locomotive of the German KWStE (Königlich Württembergischen Staatseisenbahnen) origin with outside cylinders and Walschaerts valve gear. The loco is about 1.10 metre long and will weigh approx. 100 kg.

On the left you'll find the index where you can browse through the different articles and on the right you'll find all the extra's. On the top tabs you'll find a brief description of my other locos.

Enjoy this site. Erik-Jan Stroetinga. The Netherlands. Europe.

Tuesday, 25 September 2018

Ein Offener Güterwagen [type O Halle Omk ] (part 1)

For driving the loco I'm  borrowing a 'driving truck'  (driving trolley) from a club member.  But of course I've started making my own driving truck for the T3.  I want the driving truck to look like a goods wagon. A wooden crate or box will act as load and will also function as seat for the driver. Footrests will be attached to the frame and  a hand operated braking gear will be part of the design as well.

I'm intending to build two wagons; one for driving and one for tools, firing equipment, oil cans, and other stuf  necessary for a day at the track. The superstructure will detailed and look like the real thing; the frame however will be a simplified construction, that will be strong enough to withstand a derailment, even with the driver seated on top. In my experience driving trucks on live steam model railways will have to endure some rough handling.

Offene Güterwagen   (Omk O Halle)

I've started with a so called 'Offener Güterwagen' according to a German diagram A1 (drawings from the 'Güterwagen der Verbandsbauart' , a counterpart of the British Railway Clearing House wagon standard). These wagons were known by their telegraph code Omk  O Halle .
It was typical general purpose standard open goods wagon. The first were build during the early 1900's and they were withdrawn in the late 1950'ties. It is thought that over 60.000 were build. With a loading area of 6,7 meters long (18,4 square meters in total)  and a maximum load of 15 Tons the were used for all kind of loads that needed no protection from the weather. A small brakeman's cabin was optional, sometimes only a brake platform was available, or there was no brake gear at all.
There are many model railway suppliers that have  H0-scale and gauge 1 model wagons available. I used Märklin and Fleischmann models to take measurements and details of.

I've started with the coupling hooks, the same dimensions as of the loco hooks, but now cnc- milled.

The chamfering was done on the conventional milling machine, by tilting the milling head 2 degrees.

In the four jaw chuck, the end of the coupling hook was setup for cutting the screw-thread (Mf 6 x 0.75)  

It was cut with a die; the small fillet between the thread and shaft was made to get a smooth transition of the pulling force. (a straight edge can lead to stress points and potential cracks)

A stiff spring is used for damping the pulling power, once the train is driving on the track. For model live steam operation this simple solution is adequate. 

The buffers were the next parts to manufacture. A 6 mm steel plate was cut to length and faced and drilled in the lathe. The hole was bored with a boring tool to exact dimensions. 

Working in batches is saving some time in setting up the machine tools; so these parts were made for the two wagons.

While facing and boring out the holes on the lathe, the cnc miller was cutting the contour of the back plate.

The buffer stocks in production.

The buffer head could have been made in two parts, but I had a piece of 50 mm steel rod, that was suitable for the job. With a carbide tool and large roughing cuts it took most part of an evening to make the rear side of the 8 heads.

Waiting for the next step. The buffer shafts were glued with Loctite 601 to the back plates. 

The front side of the buffer head was turned and a small radius on the diameter finished the buffers. 

A test fitting to the buffer beam.

Holes drilled for taking up the corner pieces (made of angle steel) are located in such a way that the bolts are covered with the buffers and are thus not visible in the final buffer beam.

The shaping machine was used for getting the corner pieces square and correct length. 

The longitudinal frame members are made of 40 x 20 x 5 mm U-profile. This is the smallest size profile available; it's a little out of scale and heavy; but then again the load of the wagon (the driver) will be out of scale, so some extra strength and rigidity is welcome.  
The guard irons were laser cut and screwed on the frame.

The first view of the total lengt of the two wagons. 

Instead of using separate planks (as original used), I've chosen to use multiplex plywood and cut small groves with a router, for simulating the planks.

The setup for milling the groves for the side boards

Side boards at full length.

Cut to length, the side boards were glued to the floor. 

The end of wagon, opposite the brakeman's cabin, is hinged at the top and can be opened for fast emptying a load of coal is special designed tipping cradles that were use by the German railways. The complete wagon was therefore clamped and liftedSee this video 

A hinge pin is attached to this end door. 

The top hinge of the swing end door of the wagon.

Glueing the front side board on the floor. On the full scale wagons, these side board (except the one at the brakeman's cabin) where all detachable. The wagon could therefore be converted to a flat wagon. For the model this is not that practical and would get the boards easy damaged in normal use. 

The doors are folded in the plate bending machine from 1,5 mm zinc plated steel plate.

A typical pressed door appearance is created this way.

To date (end september 2018) the frame and a part of  the body assembled for testing. Still a lot of work to be done.