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Six-Wheelers - WIP Update


MikeOxon

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Since my last entry, I have been making slow progress with my coach construction. In fact, there has been a lot of trial and error, as I tried to find a way of incorporating printed sides from my Silhouette cutter.

 

I have not scratch-built coaches before, so had a lot to learn, for which the various posts by Mike Trice in the Silhouette cutter thread: http://www.rmweb.co.uk/community/index.php?/topic/79025-a-guide-to-using-the-silhouettecameo-cutter/?p=1278380

have been particularly helpful

 

Although I had previously found that it is possible to use an inkjet printer on styrene sheet (by coating the surface first), I could not get as crisp an image as when using real photo paper. I've now evolved a system where I use photo paper for the outer layers of the coach side and 10 thou styrene for the inner layer. This allows me to weld the sides to other styrene components by means of MekPak (or similar).

 

Another problem I had to address was how to achieve the curved 'tumble home' in the lower part of the coach sides. I finally hit on a method that uses a curved brass chassis to support the lower sides. I started with a simple rectangle of 10 thou brass sheet then scored and bent the edges to the required profile. I find brass is much easier than plastic card for this sort of task, as it holds a curved profile of its own accord.

 

The brass platform also provides some weight, low down, and provides a secure fixing for the Cleminson chassis. I then glued the laminated sides to the outside of the ' upturned boat' profile of the chassis. For glazing, I used overhead-transparency acetate film, folded to a U-shape, to fit between the sides and under the roof.

 

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I built the seating and partitions as a separate module, which could be dropped inside the curved sides of the chassis. The 'seats' are simply cut from a length of styrene square tubing and serve to hold the 20 thou plastic card partitions in a vertical orientation. Side bars made from plastic card strips prevent the floor from bowing - which it does, if not reinforced in this way.

 

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The various parts fit together as shown in the following photo:

 

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The roof caused me a lot of head scratching. I tried building a box section for the clerestory out of plastic card but found it difficult to get the right profile. It could probably be done with thin plastic card and a lot of transverse formers but this was clearly going to be a fiddly assembly task.

 

Then I thought I would try folding thin (5 thou) brass sheet, which proved surprisingly tough to fold to the profile I wanted. It would have been easier with proper bending jigs, as I was just using a vice and pieces of angle aluminium as a former. As it was, I had to work on the metal rather too much, to achieve the profile I wanted and it cracked along one of the folds. I repaired and stiffened the structure by running solder along the insides of the folds but, I think I will fabricate the next design from separate sections, soldered together. The rather rough bits will be covered by thin (10 thou) plastic card roof sheeting and by the printed clerestory sides, which I made in the same way as the main body sides.

 

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The structure is now coming together and I feel that it is going to work :) - after severe doubts earlier on in the process!

 

Mike

 

Next Post

 

PS - I notice that I put the roof on the wrong way round for the photo! The clerestory lights do line up with the compartments!

PPS - The sides are only tacked together with Bluetac for the photo - I hope to achieve a better fit in the end!

PPPS - Th final coach can be seen in 'Railway Modeller', Nov.2014, "Computer-aided Cutting"

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  • RMweb Gold

Very interesting Mike. You have a lot of courage in doing things your own way and experimenting - to the benefit of the rest of us. Some people would have just made do with replacement sides for existing coaches, but you're doing a whole new coach, which is impressive I think.

 

I like the idea of the brass former for the floor and tumblehomes. But will the sides not still need to be formed also, and be kept parallel at the top? Or will the ends be enough to hold the sides at the right "square" angle?

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As Mikkels says, it's very nice to see experimental model making with great results too.

 

Regards Snitzl

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...

I like the idea of the brass former for the floor and tumblehomes. But will the sides not still need to be formed also, and be kept parallel at the top? Or will the ends be enough to hold the sides at the right "square" angle?

Good questions, Mikkel!  I'll let you know when I have the answers  :)

 

I'm hoping the ends will be enough to hold everything true but, if not, I shall put some angle members inside the eaves of the sides.  You are right to describe me as an experimentalist but I also like things to be simple, so I try to avoid complicated formers and braces. 

 

Sometimes, following the prototypical construction methods can be fascinating, but they are often not appropriate for a small-scale model.

 

Mike

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  • RMweb Gold

Good point about keeping things simple, Mike. 

 

Quite apart from the new techniques etc, it's very nice to watch a clerestory 6-wheeler taking shape. I have always liked the "old-world" feel about those coaches.

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Thank you, Mikkel.  I can now confirm that 'welding' the sides to the ends has been sufficient to hold their shape.  On the next one, I think I will incorporate a 'lip' on the edges of the roof, to conceal the join and ensure that the sides are held along their length. 

 

I've now added solebars, made from styrene channel.  I fixed the ends of these but left the middle section free to flex slightly when the Cleminson centre unit slides.  I intend to use the Silhouette to make some Mansell centres for the wheels.

 

Mike

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