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 German (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.

Friday, 22 February 2013

Starting the boiler fittings

 The handwheel in Solidworks according to the german standard. 

Turning from a solid brass rod the contours of the handwheels. Outer diameter, 22.5 mm.

With several lathe tools the handweel gets its shape. 

The CNC program is for the spokes is loaded and ready for milling with a 3mm end mill.

The controller software USB-CNC is running on an old laptop. 

 The progress of the milling cyclus (the cutter wasn't too sharp)

 Before and after the CNC milling operation which took about 20 minutes. 

After finishing with the lathe the first batch of wheels. The square hole is yet to be punched.

A week of CNC.

Boiler fittings in progress.

Sunday, 17 February 2013

CNC needed for numberplates

Loco number plates for the T3 are not available in the model engineering trade.  I had a sample of a real shed sign, which was the base for my loco plates.

The design was done in Solidworks. 

To make these, I had to buy and convert a milling machine to CNC. A model engineer gave a tip to look at http://www.impulsecnc.nl. This supplier gave me good advice in how to build a home-made CNC milling machine and which components were needed. I started out with the basics: power supply, drives, USB-CNC controller and stepper motors. A cabinet was bought second-hand.

 The wiring-up was done according plans. Simply follow the given instructions and connect all the pins of the controller board to the drives and power supplies.

A setup had to be made to connect the motors to the spindles. These are stepper motors of 4.5Nm connected to ball screw spindles with an pitch of 5mm.

Setting up the USB-CNC controller required some jumper settings. On the drives the dip switches had to be set to a given motor Amp and micro step.

First test in milling with the new machine in PVC. 

The complete set-up of the Wabeco F1210 as a CNC milling machine.

The steam turret on top of the boiler, also done with the aid of the new milling machine

The number plates on the cab,

Wednesday, 13 February 2013

The Solidworks drawing

I started out with Inventor software for the 3D modelling of the loco. At my work at Fontys University of applied sciences, I have made to change to Solidworks because we got better support with this software. To get familiar with the 3D modelling CAD software, a 3 day starter course isn’t enough; so I had to get some hand-on experience myself.



What better way than to make your own drawings. Designing the locomotive in 3D is great to do. You’ll get an instant view and ‘feel’ of how things will look on the loco. In the assembly drawings, all the parts can be fitted and checked on the virtual locomotive.


Even the total weight of the loco can easily be determined. The valve gear can completely be tested in forehand; so when I start to cut metal in the workshop, I know the parts will fit. From every 3D modelled part a 2D workshop drawing can be made very quickly. A change in the 3D part will be automatically up-dated in the 2D drawing.

February 2014

The first concept drawing of the driving wagon. Based on an so called Omk open goods wagon of the German railways. The drawing is based on measurements I took off a gauge 1 Märkin wagon. This is a model a typical European open wagon with a 4 meter wheel base, 6.7m long loading floor with a 15 ton loading capacity. 

March  2015

May 2014

May 2017, render in Solidworks; final livery

Loco with the open wagon (for the driver to sit on)  and beer wagon. 

The Solidworks drawing can now be downloaded at GrabCad  or directly from our model engineering society site www.stoomgroepzuid.nl

Sunday, 10 February 2013

The smokebox

The smokebox
This is a classical design, with the flared out front plate. The Stroudley A1 Terrier locomotive has the same kind of smokebox shape.  That loco was from the same period (1880’s).

 I used a piece of steel pipe (160mm diameter) on which the front plate is silver soldered. 
The door is a combination of a steel turned disk and a curved steel plate, also silver soldered on. I’ve used the standard dart design for closing the door, because I couldn’t figure out how this worked on the original Württ. T3.

The base of the chimney is formed by fly cutting with a boringhead. This is set to the radius of the smokebox.

After leaving the milling machine, the outer shape was turned in the lathe.

Although a extreme long overhang from the chuck, boring out the chimney was done in this set-up. Easy does it! :-)

In three steps the inner conical shape was turned.

The rotating center in the tail stock is inside the chimney, when the out side was turned. For both operations (in and outside) the cross slide was set to an angle of a few degrees.

Drilling holes for mounting the smokebox on the frame

The smokebox saddle consists of two strips of mild steel

Finishing the hinge by hand

The hinge is made from a steel bar, that was first reduced to thickness of 2 mm in the shaping machine. You’ll see in the photo the 8mm square lumps, that became the eye of the hinge. This job has been done by filing.  

The complete assembly.

The cylinder castings

These are the cylinder castings that came with the set of locomotive parts.

(They are 90mm long and and have an out side diameter of 66mm. The finished bore is 40mm).

It is the first time for me that I’ll incorporate cast iron cylinders, all my previous locomotives are fitted with bronze cylinders. 

The boring of cylinder, with only light cuts. The set-up in the chuck is far from desirable.

This cast iron is of a good quality (no hard spots) and machining in the lathe was done with carbide cutting tools.  Although they are large, they could be clamped in the 3 jaw chuck. This made turning a straight forward job.

During manufacturing of the cylinders there is not much difference with bronze, but the usageof cast iron cylinders on the finished locomotive will be different. This material depends on good lubrication with first grade quality steam oil. Otherwise rust will set in quite quickly. Also all the condensated water has to be removed via the drain cocks after the run I'm told.

Honing the bore with honing stones

After boring out the cylinder to the correct diameter (in this case 40mm, which is small for a 7.25” locomotive) anautomotive honing tool was bought and used for finishing the bore to a smooth surface.
I’ll be using Teflon piston rings of the same design as used in the Mona, Dacre and Didcot. In these locomotives they proofed to be successful and never needed any maintenance

A smooth finish is obtainable

The cylinder port face on the original Prussian T3 (for which these castings are intended)  has an inclined angle. In my design this will not be incorporated, so the shaping machine was put in action to remove the surplus of material. The shaper leaves the port face with a very flat surface. The machining marks, left by the tool, are all parallel and in straight lines. 

This will be near to perfect to take up a small oil film, on which the valve can glide. The slide valve it self will also be machined in the shaper, but the set up will be arranged so that the grooves left by the cutting tool will be 90 degrees to the ones in the port face. I’ve used this method before with the other locomotives and the slide valves and port faces still look very good after years of service.  


The cylinders partly finished, with the covers in front. These were made by Wolfgang years ago and can be used without any problems.  

Cutting of the steam ports. They are 4 mm and 8 mm wide and were cut with a small 3.5mm cutter. You'll see no chips in the picture, because I've used a vacuum cleaner to remove them after every cut. This way I kept a clear view on the process and the chips would not clog up the relative deep ports during the cutting process.

Set-up for drilling the steamports

The exact angle was diterment  in Solidworks, before drilling!

A lot of holes

The steamports, avoiding the tapped holes.

The light beam shows the exact match of the holes.

Opening out the steamports at the cylinder ends.

Providing clearance in the cylinder covers.

The steam passages.

The cylinder cover.

The portface with steam and exhaust ports.

Fabrication of the steam chest from solid bar.

Drilling and tapping the holes for taking up the steam chest

Bronze valves

The piston rod and gland

Both glands on the covers

The pistons whit the grove for the Teflon piston rings

The Teflon U-shaped ring. This was turned from solid Teflon and sits with a side play of 0.2mm in the grove of the piston. In the depth there is a clearance of approx. 0.4 mm.

The bronze piston in position.

The brown stuff is copper grease, which is used when screwing the studs in the cylinder.   Hopefully the studs are removable from the cylinder; even after many years of service.