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Pause for Reflection


MikeOxon

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Photographs can be very cruel! Looking at the photo of the handbrake ratchet in my previous entry, all I see is the huge tab, which I have not filed smoothly. It's invisible in practice but not on the photo! It's a real test, to subject modelling to this type of scrutiny.

 

My favourite weapons for removing those pips, as well as flash on white metal, are emery nail boards from the pharmacy. They're cheap and disposable, and don't get ruined by white metal, so saving my precious needle files.

 

It was very pleasant to read the favourable comments on my N6 horsebox. Yes, it was a bit challenging at times but the sort of challenge that results in a real sense of achievement and of having learned something. Since building that kit, I have been thinking about other additions to my vehicle fleet, to replace several RCH wagons with something more characterful. I saw some three-plankers with rounded ends on Mikkel's blog at http://www.rmweb.co.uk/community/index.php?/blog/75/entry-12025-in-the-red-gwr-1900s-wagons/ I rather liked the look of these and thought that, after the N6, they should be pretty simple ..... shouldn't they?

 

Well, most entries on this site seem to show how wonderfully people have overcome difficulties and produced beautiful models but that is not the case here. I've been making rather a mess of things but hope that it will all prove to be part of a learning curve.

 

The David Geen kit for the GWR three-planker contains some very nicely moulded and detailed (on both sides) castings for the sides and ends of the wagon, plus a few other small castings and a piece of planked plasticard, which I assume is intended as the floor (though not cut to size).

 

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Kit components

 

The kit includes plenty of information about the prototypes but very little by way of building instructions, apart from a recommendation to use low-melt solder or epoxy but, preferably, not superglue. I soon found that there are no location pips or raised edges, to assist with location of the parts, either horizontally or vertically, The ends of the sides are simply mitred at about 45 degrees. Also, because of the curved tops to the ends, and the V-hangers below the solebars, I couldn't set up the parts upon a flat surface! I could not think of an easy way to jig it up for soldering, or to hold it firmly while epoxy hardened, so I decided to try superglue (against recommendations).

 

Actually, I quite like superglue and find it effective, with the proviso that parts must be close-fitting and free of surface contamination (including any residual mould-release agent.) These parts weren't like that and there was a distinct taper at the ends (which I think I can see on Mikkel's model also). So, a bit of gentle work with the nail boards provided bright, matching surfaces that seemed to fit together pretty well.

 

I decided to hand-hold one side and one end at right-angles (by eye) and then tack them together with superglue, then count to fifty as it hardened. Good! Next the other pair and now to put the two bits together, to make the rectangular plan of the wagon. I held the pieces in a pair of ratchet clamps but then realised that the side pressure from the clamps forced the mitred joints to push the ends apart! As the photo below shows, the thing looked far out of square and, in trying to sort this out, my tacked joints failed ... 'bother' ( actually, I used a word with different letters after the 'b') Oh well, clean up and try again with the delicate balancing act.

 

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Use of ratchet clamps

 

By now, I had decided to use this wagon as an experiment, to discover better ways of building the next one. I cut the plasticard to size for the floor, fitted the rather horrible mis-shapen buffers, which didn't fit the holes in the buffer beams, and carried on with the rest of the assembly. When I slotted some wheels into their bearings, it was clear that things were very out of true - the axles were far from perpendicular to the axis of the wagon.

 

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Mis-aligned axles

 

Right, I've now paused for reflection. I find that problems like this find some recess in the back of my mind and churn away there. A potential solution then pops out at an inopportune moment - for example, at 3am, when I am trying to sleep. In this case, the idea was to cut out a rectangle of brass sheet, to form a rigid floor / chassis, with fold-down tabs to support the ends. I could mount the sides onto this chassis and run a fillet of epoxy under the floor, to make everything secure. Then I could prepare the sides to receive the two ends, making sure that everything was square against my brass template.

 

I'll stop at this cliff-hanger, in case better ideas pop out in the next day or two, but I think (hope) I'm on the way to a successful model. I must find some nice buffers, too!

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The easy way to solve a problem like this is to buy a set of brass compensated W irons (assuming such things are still available in 4mm) and set them up using a simple jig - which can either be bought in or made. I find that if a wagon is not square, and cannot be made so, it can at least be made to run properly by following this method. This is not my idea originally - it was Iain Rice who pointed me in this direction. It is often simpler to do this than assemble the wagon as designed - white metal often distorts and even plastic kits are not always perfect.

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By the way, superglue does the job perfectly well. I have some white metal 7mm scale wagons built circa 1991 with this method and up to now only one has failed in service. Solder is better, but not essential.

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Thanks for those thoughts, Poggy1165.  Iain Rice's book on building etched brass kits has been a constant source of inspiration and I do like his definition of a 'kit' including "the kit designer must describe how the kit is to be built, and he should have addressed and solved all the problems encountered in building the model at the design stage".  Fortunately, I quite enjoy 'problem-solving' :)  I agree that superglue sometimes gets a bad press but is great, when used correctly. I'm also testing Bostik 'Serious Glue', which seems quite promising.

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I agree with Poggy's suggestion. Amputate the running gear and rebuild it using etched W irons. On other vehicles that I have encountered, it is not uncommon to find that the two sides have been cast from a single pattern. As a result, if the axleboxes on the pattern are slightly asymmetric, this will be faithfully reproduced on all the castings. You can therefore have either a square body, or a square chassis - but not both.

Best wishes

Eric

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  • RMweb Gold

Hi Mike, I agree about the superglue. It's underrated for glueing whitemetal together. I now swear by the gel type, which has a bit of a filling effect and therefore works very nicely for people like me who don't get along so well with fine tolerances :-)

 

I don't recall having problems with mis-aligned axles on the two 3-plankers I've built, so not sure what has made the difference. I usually file the solebar ends as appropriate to ensure a square fit, if that is any help. When I have glued all the sides I sometimes hold the model between all four fingers and tweak it until it is square. Cave-man technology but it works for me :-)

 

Here are some more photos of the first 3-planker I did (although that was built with Araldite): http://www.rmweb.co.uk/community/index.php?/blog/75/entry-6024-3-plank-open-in-gwr-red/

 

If you decide to go for new W irons the MJT ones are really nice.

 

Img_1557.jpg

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Thanks for all the suggestions. I think my own clumsiness was the main reason for mis-alignment, as the cast w-irons are actually separate from the side castings. The instructions suggested fitting them first, which I did, but it would be better to leave them until later, so that they can be aligned correctly.  I'm going to try my brass floor idea first and may also try the MJT etchings.  I enjoy problem-solving :) 

 

Mike

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Mike

I don't see any sign of a really flat surface in any of your photos.

My method for building kit wagons involves assembling them upside down on an old mirror using a miniature set square.

I must admit that I can't get on with Superglue and whitemetal and solder all my kits together, but thats just me.

As Burgundy says ' Not all castings are precise' and it could be a good idea to put mating castings together back to back to see if any end of the solebars needs trimming to get more accurately matching sides and a more square end result.

 

For Mikkel, What is this gel type that you mention please?

 

Michael

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To test Burgundy's suggestion, I photographed one wagon side and then used Photoshop to make a mirror image.  This shows that there is indeed a small discrepancy in the placing of the bump stops and V-hangers.  Since I aligned the axleboxes with the bump stops, this can explain the mis-aligned axles.

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