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How to make a Ballast Wagon, in a bazillion easy steps.....

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Afternoon all.


In advance of this evenings posting by the IRM team, I thought it would be timely to run through what is actually involved in making, not one, but actually two wagons, utilising the same chassis. As one can imagine, the Cement Bubble and Ballast Wagon have violently different upper and lower components, but the base chassis is identical. So one problem from the off is where to screwfix the bodies to the chassis', in a place that works for both. Thankfully that was sorted in the CAD stage and it comes down to a simple thing of making them....Now this is after months and months of getting the CAD approved first, which by now you've all seen I'm sure.


It's like a big jigsaw, and at the start the manufacturers start by cutting large lumps of steel which will all interlock eventually. This took a bit of figuring out for us, get our heads around cavity and core units, but we were off!




Spark Eroding is the term you need to google if you'd like to learn more. Essentially, every single cut, groove and rivet on the chassis is individually made of a copper electrode. They are the items in the upper part of the image. The steel lump in the middle is going to be the female part of the chassis, and you should be able to see the NEM pockets on either end.





As I understand it, they are placed where they are supposed to go (robotically) dunked in some magic fluid, a charge passed through, and as the copper is pushed toward the steel, it sacrifices itself, and there is a perfect shape of the copper unit left behind. Needless to say, this process has to be repeated over and over again for each part.




You can see the robot arm clamping a copper piece as it's off to create another rivet, makers plate or something small on the solebar of the chassis...




So on the die on the right, you can see the gates cut in - these are the channels that the plastic runs into to get into the wagon sides. But just keep a note of the jigsaw shapes of the dies for the moment...




No prizes for guessing what wagon this is from, but it shows the little rivets dotted around the base where the bubble joins the chassis. Hnnng.....




Then there are the slides for the side of the hopper, with the locations noted for the supporting strakes outside.....




Now all these parts fit together as a complete puzzle, interlocking with each other, leaving only the gates and runners open for the plastic to be injected into.




I'm assuming here that the colour is related to a test fit/squirt, like a release agent, but you can make out the male and female parts of the mould.




The last part of the process, that I have seen at least, is where all these parts are assembled together and put into the rig you see. The four holes on either side of the shape there represent where the inside of the ballast hopper is, and all the metal dies pile on. So you've seen how the majority of both wagons are done, but there is one vital ingredient, and that's the detail. Here's a (mighty wobbly) shot of the detail rig, both male and female. At the bottom you make out brake hangars, coupling bars, ballast release wheels, and cement wagon ladders. All the detail for both wagons will be on the same die, design clever they call it.


(The ladders will be metal on the final bubble, they need to be made in plastic to make sure they fit etc.)




Once plastic is squirted it comes out on sprues, much like your airfix kit. All in one piece....




These are neatly removed, the detail added, and the whole lot assembled. I'm told the process of making one is less than a minute, but what these manufacturers have done in 18 weeks is quite remarkable. After this they will be sprayed (I'm trying to make the paint samples to send to them currently) then tampo printed with the running numbers and oddball stencil placement and fonts we are so used to with the prototype, but for the moment that's all I have to share.


Most manufacturers don't ever go into this detail for some reason, but we felt since ye've been along for the ride since day 1, it would be nice to see what happens behind the smoke and mirrors. Props to our Chinese Engineers, who may have rubbish cameras but they know what they are doing, and Dave "Handy as a small pot" Jones, of DJModels, for making all of this possible.














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Excellent Richie. The Scalefour mag did a piece on Parkside Dundas a few issues ago and it explained a lot of the process for their wagons. This is far more advanced without doubt due to the cylindrical nature of the bubbles. After a few looks I have gotten my head around it and it is fascinating. The amount of small pieces in the dyes is amazing and when you see it like this it makes the models more personal. Thanks for sharing it was really enjoyable and explained a lot. Can't wait until tonight.



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