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Preparations on building a type 29

Some pictures of ideas on building parts for a type 29 steam locomotive. Basic method is by exploiting the milling machine


The last survivor still in running condition in 1995 in Leuven.

Frame


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The frame parts cut from PB.

The type 29 has a bar frame. That can be milled from flat sheet. To obtain a robust frame a sheet of 0.8 mm Phospor Bronze was glued to a piece of sacrificial MDF and the outline of the frames were cut. In this case with a rather coarse milling cutter of 1 mm as the 0.8 mm were gone and any smaller looked a too great risk for this hard material.

Wheels

Another method for producing spoke wheels


drawing

A basic wheel drawn in 3D using ViaCad.


milled

The test wheel cut from clear plastic on a piece of polystyrene as carrier.


set free

The wheel pressed out of the carrier

A piece of 2 mm polystyreen is acting as carrier. On the lathe a 1.5 mm thick disc with a 2.5 mm stub was turned from a clear material. Although I thought it to be polycarbonate it is more likely PMMA as it seems a bit soft for PC. A 2.5 mm hole was drilled in the polystyrene and the stub glued in with cyano. Than the machine did its work and it certainly looks like a wheel that is coming out. A 0.3 mm straight cutter was used for the contour cutting. So far so good, looks promising, now assembling and a test on stability


wheel set

A set of assembled wheels made from POM with silversteel rims.

A set of assembled wheels made from POM with silversteel tyre. Although not perfect they will do the job, assembly and rim production need attention for an optimal product. The above 10x enlargement shows apart from the filth that an extra step for rounding of the contour cannot do harm but this requires a round nose tool not available at the moment. These centers survived the treatment of finishing the tyre and drilling the center on the lathe, thus seem rigid enough. Of course there is a chance the rims come off, these are glued with cyano which seems allright for bonding to metal according Wikipedia. If necessary producing a groove at the inner contact area for an extra ridge of glue may prevent such. Optimising the process requires producing some tools for the lathe to assist production of tyres as these take much more time than the wheel centers due to tool changes, necessitating measuring actual dimensions.


wheel drawing

Variation on the theme with integrated balance weight.


wheel

The result coloured with a filt scriber, looks a bit smudgy with this enlargement but with some cleaning using a glass fiber brush all loose material will disappear.


wheel

a pair of black wheels

A pair of wheel centers produced from black POM, much easier and cheaper than trying to colour the white POM with Dylon paint. The right hand is the main driver, this shows some flash due to using a different cutter and cutting strategy in trying to copy the blended surfaces of the original drawing above. This was not succesful as you can see, apart from the flash, the surfaces of the spokes are still flat. Another attempt will be done with smaller steps and a finer cutting program for only the top 0.25 mm. The top of the spokes are no longer flat although its not to 100% satisfaction. The surface of the balance weight is more smooth and is now glossy. I noted some stability problems with the carrier moving slightly due to forces, a more stable carrier material will take care of this.


wheel

A handful of wheels

Tyres were produced on the Proxxon from automate steel. Using a set of quick change toolholders really helps to speed this process up and gives uniform results with less measuring in between. The next practical step is production of the axles and drilling the holes for the axle and the rods. This requires to produce a collet to hold them in the lathe for drilling the holes.

type 29 sideviewNMBS 29.013 in 2010 in Dorinne-Durnal at the CFB

Desk study


wheels

Starting a desk study, track and wheels as existing drawing parts.

A start was made by setting up a drawing of the loco in Cinema 4D, this serves the purpose of getting all the necessary dimensions from the drawings and make subdrawings for the components and form ideas how these can be produced. The STL file of the wheel drawing was imported and visualised similar to the type 16 design study ,see type 16. This should lead to drawings for the upper parts that can either be made using the available tools in the workshop or alternatively used to order externally produced 3D printed components. Setting up this arrangement makes it immediately clear the that maximal dimension for the wheel flanges is 0.3 mm otherwise the wheels are not going to fit the chassis.

rookkastdeur smokebox door.

The smoke box door, a job similar to that on other models only the circle with bolts is additional.

frame + boiler Boiler with firebox and smokebox including door.

Constructing such a boiler is best done from 2 parts soldered together, a boiler made from brass tube on the lathe and a separate firebox which can be constructed similar to the one for the type 25 from brass on the milling machine.

frame + boiler sandbox on top of the boiler and a first impression of the cylinders.

Construction of the cylinder block and steam pipe, basically a set of 2-D profiles, one for the cylinder block and one for the saddle with the vertical center plate where they are bolted together. The cylinder and steam distribution and steam pipe are inserted as cylinders. The whole lot is a symmetry element of course. Construction in metal is possible by milling 2 of these profiles as one unit in pcb material and space these apart using the cylinders as distance keepers and wrap a thin sheet of metal along the outline. The pcb material allows to use the cylinder block as insulated frame spacer solder. Alternatively the block can be entirely milled as single piece from plastic using 2 sided milling from front and back or as 2 single sided milled pieces glued back to back.

cab added cab added

front front of the footplate.

chimney deflection plates and chimney added.

appendages on boiler more appendages added to the top of the boiler.

Comparing the generated pictures with that on the 2010 photo shows several deviations particularly at the firebox end. A view into the cause revealed that some of my working copies of the drawings have different x and y scale problably due to some scanner or printing operation. This caused the deflectors to be too high and also the end of firebox did not sit correct. On the above picture these items are repaired. Also there exist several differences between the 29.013 and my drawings. Some of these do originate from the new boiler built in Meiningen, particularly the number and position of the washing plugs, the position of the electric generator and the 180 degrees switched steam connection in front of the sandbox. The cab is now modified to reflect the correct height and has its partial back wall and there is a rainstrip on the roof.

sand pipes on boiler sand pipes on the boiler.

coloured black and green some colour added

componentsA set of fireboxes and cylinder blocks from above drawings as 3D printed items

The above drawings were fed to a 3D printer to produce a firebox and cylinder block. With a bit of finishing work these look to be usable. Particularly for the cylinder blocks this is a time saving option.

copyright: Henk Oversloot
start: 10 june 2013
last update: 9 feb 2016