Resin Casting open wagons

[David Holman]

 

Having almost driven myself to distraction scratchbuilding multiple SLNCR wagons, I decided to explore the possibilities of resin casting. I looked up casting materials on the web, but recently there has been an advert in Railway modeller for such things & I can only say how straightforward the process is.

Included are some photos. First you need to produce a 'master of the model you are building. In this case one side and one end of a 4 plank and 6 plank open wagon. I used 40 and 60 thou plastic sheet, scoring for the planks and then adding strapping and metalwork from microstrip. I also used a wire brush to add some wood grain to the planking.

The master was then stuck to a larger sheet of plasticard and a low 'wall' built around it with more plastic strip to make a mould. Then followed the casting kit's instructions, mixing the setting agent to the latex 'goo' and poured this into the mould. 24 hours later, this had set and I had latex moulds of my wagon sides and ends.

The resin comes in two parts and is mixed 50/50. A cheap set of measuring cups from a pound shop helped with getting quantities right and avoiding waste. The resin mix goes into the moulds and within an hour has set, so you can quickly produce multiple copies. The level of detail picked up is very impressive - the wire brush scratched wood grain really shows up well, as would finger prints and any crud, so care is the order of the day.

Drawbacks? Very few. It helps to keep the moulds level as the resin is initially very watery and flows really well to where it is not wanted. Bubbles can form in the resin mix, but it is easy to prick these out with a cocktail stick while still wet. Also, a bit of thought needs to go into how thick you want the castings to be. Important with an open wagon, less so with a van.

I've used cyano to glue the pieces together around an 80thou plastic floor. Slaters wheels and JPL whitemetal castings cover the underframe, with brake gear coming initially from the scrapbox - Parkside and Slaters kits seem to provide plenty of spares which fellow club members are happy to off load. Have managed to cast some 'V's and brake levers from the originals in the kits, but they are inevitably a bit thick and fragile. Haven't tried casting more 3D shapes yet, but can see all sorts of possibilities for things like fence posts, chimney pots etc.

Evidence suggests the latex moulds should be good for 20+ castings, while I still have plenty of goo left to produce more if needed. The casting kit cost me about £50 and should produce enough models to make it worthwhile, if only in the time saved. As anyone who has scratchbuilt wagons will tell you, the sides are the cheap bit, it is the wheels [£9.50 in O gauge], buffers [£4 - £14 depending on type and quality] & couplings [£5] which cost the most. Makes those new Dapol RTR opens seem very cheap at only £30 or so... Shame they are 7 plank - my research seems to suggest most Irish opens are 4 or 6 planks...

[Flying Scotsman 4472]

Thanks David some great info there and well explained.

[scahalane]

Thanks David very informative. This weekend I hope to do some of my own resin casting for the first time, so we'll see how I get on.

[Galteemore]

Late to the party here, David...but have you any experience casting vans or box wagons? Trying to work out how the vertical side and end frames would match up...

[David Holman]

Vans nominally easier than opens, because no interior detail required. You just have to be careful with how ends and sides mate up. The main issue is if the casting is too thick (because too much resin was poured into the mould), so best to avoid overflowing or a meniscus, or you end up having to do a lot of filing.

 One option is to mitre the corners, but I've found that just filing down the outer edges of the ends (to make a simple rebate) works well enough. Vans with lots of strapping give extra thickness to the ends to make this work. Also, have found that thicker, slower setting cyano is better for assembly - quicker than 5 minute expoxy, so less time sitting holding the pieces while it sets!