It's All Iain's Fault!

Yes this post is definitely all Iain's fault, but I don't mean that in a bad way.

As you all know I've recently been 3D printing lots of small narrow gauge wagons. In fact I'm now up to five different wagons: an 8ft freelance flat wagon, 3 bar slab wagon, an Aberllefenni Box Wagon, a 4 bar slab wagon, and most recently a Rhosydd rubbish wagon. These models have all been fun to design, print and assemble and Iain has kindly provided lots of useful prototype information for a number of them. I also have a couple of other wagons under development that are proving a little tricky to get right (mostly due to weird issues with the 3D printing process) but I thought I was slowly running out of scale drawings that would cause a distraction from building Canopus (I still haven't bitten the bullet and permanently attached the coupling rods). It was at this point Iain pointed me in the direction of Narrow Gauge and Industrial Railway Modelling Review (which I mentioned in the previous post). More importantly he pointed out that there were some very interesting scale drawings in the free sample magazine available from the website. A quick glance and not only had I subscribed to the magazine but I'd started work on yet another wagon model. So you see this model is definitely Iain's fault; thanks Iain!

Pages 33 to 41 of the magazine cover a multitude of wagons that were all used at Trevor Quarry on the Lleyn Peninsula in North Wales. Interestingly this was a granite quarry rather than the more common slate quarries found in North Wales. The specific wagon that caught me eye in the magazine was the rather odd, 3 sided, breaker wagon; the magazine has a photo and scale drawings on pages 35 to 37. While a 3 sided wagon might not have wide spread use it intrigued me enough that I set about designing a 3D print. I'll start by showing you the finished model and then explain how I got there.

The photo is of course a little misleading as this model is actually just 3.2cm long by 1.85cm wide and 1.35cm tall; in other words not very big at all. The relatively small size of the model also causes a few issues when designing it as some parts were too thin to be printed and some parts I decided might cause a problem when printed. This means that the model is actually a mix of 3D printed resin, brass sheet, and some standard copier paper.

The two problem areas that I identified when designing the model were the metal supports at the open side of the wagon, and the protective strip along the top edge of the side wall. These were problematic for different reasons and due to their shape required different solutions.

The two upright supports were a problem as I can't print parts that thin. The minimum wall thickness is 0.3mm but if I'd printed the parts I would have had to widen the wagon to make them fit and to keep the correct proportions. And of course the parts would have been very fragile and liable to break if knocked about. Fortunately the part isn't a particularly complex shape and so it was easy to cut and fold two small pieces of 0.12mm brass sheet to the required shape which could then be glued to the resin print.

The protective strip along the top of the side wall was a problem for a different reason. While I could have easily included this in the model, I've found that overhanging horizontal features, no matter how small, tend to cause other details to be obscured. This is due to the support material reacting with the printed resin. In this case it could easily have led to the side planks ending up with strange markings and would probably have completely obscured the gaps between the planks. My original intention had been to use brass sheet to add this part as well. Unfortunately, even with the hold-and-fold, I found it impossible to make the U shaped part. In the end I just made the part from 100gms copier paper which was then glued in place.

The final touch, before painting, was to add some rivet detail to the new parts which are simply Archer rivet transfers from sheet AR88025.

Painting was my now standard approach for aged wagons. The whole wagon is given a matt black undercoat. The wooden parts are then roughly painted with khaki (Model Color #988) and then a black wash. Drybrushing of khaki, brown sand (Model Color #876) and dark sand (Model Color #847) then follows, before another thin black wash and final drybrushing with dark sand. The metal parts were then painted black (to cover over paint from the wooden parts) and then dry brushed with London grey (Model Color #836) and dark rust (RailMatch #2405). A few wafts of matt varnish then tone down and seal the paints.

As with the other wagons I've printed recently I'll happily sell you one via Penistone Railway Works. I'm not sure there will be much interest given the rather odd nature of the wagon, but it's available if you want one, along with full instructions for adding the extra details.

Having built the breaker wagon I'm tempted to have a go at the mill wagon on page 38 of the sample issue as it appears to be pretty much the same wagon with some additional parts. Watch this apace!