Reinventing the Wheel

A recurring problem when modelling in OO9 is wheels. There are actually two problems. Firstly there are only a few different sizes of wheels available which limits the locomotives and wagons you can accurately model. Even if you are lucky enough to find wheels of the right size the second problem is likely to bite in that they will be of the wrong design. Fortunately many of the available wheels are actually metal tyres around plastic centres, and so as an experiment I've had a go at producing an alternative design by 3D printing replacement centres. I actually started this a while back but managed to misplace the printed parts.

To make life as complicated as possible I've tried to produce some wheels that could take crank pins for modelling inside frame locomotives. Specifically I've produced centres for a Deutz diesel locomotives.

My best guess (from that photo and some other drawings) was that the Parkside Dundas 5.1mm wagon wheels where the closest size wise but having seven curly spokes would usually rule them out. Fortunately, like many other wheels, the plastic centres push out. Some careful measuring with a set of digital callipers allowed me to determine the main dimensions of the centre which I could then use to design a Deutz style replacement. Probably more by luck than design the centres are a perfect fit inside the tyres and are a tight push fit to the original axle -- I've painted the centres red as the FUD prints are difficult to photograph.

Unfortunately I designed the centres to take a 16BA screw as the crank pin only to find I'm actually out of stock so I haven't been able to test that aspect. The plan though would be to fit a screw into the centre and then cut the head off, slide the coupling rod on, and then use a 16BA nut to hold everything in place. Alternatively you could slide the coupling rod onto a screw and screw it into the wheel so the screw head holds it in place. You'd then cut the screw flush with the back of the wheel and file the screw head flat. Either should work, but I'll have to wait until I get some 16BA screws before I know for certain.

One other interesting thing I've discovered is that the Parkside Dundas wheels, and hence my replacement centres, use the same diameter axle as the O14 axles available from KBscale. This is great as it means that you could replace the axle and model outside frames with flycranks. Usually you can't replace the axles as each manufacturer uses a slightly different size so this is very useful. Of course if I'm designing my own plastic centres then I could design them to fit any diameter axle.

For a simple experiment it shows promise although until I take the next step and build at least a rolling chassis I won't know for certain how well it will work.

Something to Pull

Having taken delivery of his shiny new locomotive the factory owner had really enjoyed running it backwards and forwards along the short line he had had laid within the confines of the factory. While seriously fun to drive, he was aware that he had, at least partially, bought the locomotive to be useful and to help move things around the factory. Unfortunately there wasn't much room in the cab to carry things so he needed some wagons. He didn't need anything fancy, at least to start with, just a few flat wagons that boxes and sacks could be stacked on so he made a visit to the factories workshops.

The friendly engineer who ran the workshops was fairly certain he could build a wagon or two for the bosses new toy, but he wasn't sure about the wheels so he ordered some from a Scottish company he'd done business with in the past. Once the wheels, all 20 pairs on axles, had arrived the engineer set about measuring things. First he measured the wheels, then he measured the locomotive and the track, then he set about drawing a design for a wagon; something the lads who worked for him could bodge together from the timber laying around and a few metal parts. A few days of sawing, bolting, and general work later and the engineer had three completed wagons in front of him that just needed a lick of paint before the wheels could be slotted into place.

Okay so now that the backstory behind 77 Box Lane has been fleshed out a little further we can return to reality. Now I'm sure I could have bought kits to make appropriate wagons but I decided to have a go at doing some 3D printing. As some of you will know I've had plenty of success with 3D printing OO gauge models, although last time I tried to print something to run on 9mm gauge track, an N scale wagon, I didn't have quite so much luck. Having recently used 3D printing to fix my fridge, I thought I'd have another crack at creating a model to run on 9mm track, but with the added advantage of modelling at 4mm scale where the supporting structures would be twice as thick as when I tried the same in N gauge.

On previous occasions I've created models based on what I think looks right rather than how I think it would have actually gone together. This works okay but doesn't give you any real insights into how you might actually have built the original item, or how you might build a similar model from modelling materials. This time I took a slightly different approach. I created the separate parts (planks, bolts, brackets, etc.) and then duplicated them as needed to essentially build a virtual kit of parts which I then assembled into the final 3D model. I'm not sure if this is a better approach or not, but it seems to have worked in this instance.

Yesterday's rather abstract post showed the three wagons (I grouped three into a single model for printing purposes as it was more economical than printing separate wagons) being cleaned. The models are printed in what is known as Frosted Ultra Detail material which is always covered in the remains of the oily support material when it arrives and this has to be removed before you can paint the models. I've found that soaking them in warm lightly diluted washing up liquid works well. I've checked and the 5.1mm wheels I ordered fit perfectly, but I'll hold of showing you them fitted until I've painted one.

I am, however, happy enough with how they have turned out to make them available via Penistone Railway Works, so if you fancy a simple, reasonably priced, wagon or three you know where to go!

Today's Post

The post has just arrived which included a very interesting box of bits for the new layout:

I'll go into more detail as I put each thing together but there is the wonderful little diesel loco from Narrow Planet, a workman's coach from Meridian Models, and a set of Greenwich Couplings and associated uncoupling magnets etc. all ordered from Parkside Dundas. It's a real shame that due to work meetings I'm not going to get any modelling done for about a week.

In Good Company

I've recently spent some time (figuratively) crawling around under coal wagons inspecting their braking systems, in order to try and design a simple, but accurate, representation that I can add to my 3D printed underframe. One of the things I've discovered (two excellent resources are here and here) is that while the brakes on my model coal wagon worked so well that the wheels wouldn't turn, in real life they wouldn't have worked at all, as I fitted them the wrong way around.

By the late 19th century most wagons were fitted with a simple lever brake on one side only. The diagram shows the break lever (in red) in the off position. To apply the brake the lever was pushed down. This turns the shaft (blue) and connecting arm (green) clockwise, which in turn moves the two push rods and attached brake shoes (black) outwards and onto the wheels. As you can see this is a really simple, but effective, braking system. The one downside being that if you had to apply a brake to a run away wagon you might have to cross the track to get to it, which may well be bad for your health and well being!

The easiest way to solve this problem is to simply fit a completely independent brake system to the other side of the wagon, but with the brake lever always at the right hand end of the wagon (so it appears to always be in the same place no matter which side you view the wagon from). This means that when you view the connecting arms from one side of the wagon, the nearest turns clockwise while the one on the other side turns anti-clockwise as the brake is applied. This means of course that you can't simply connect the two brake systems together by extending the shaft (blue) the full width of the wagon.

To overcome this problem, and to allow either brake lever to be used to apply both sets of brakes requires a clutch mechanism (shown in yellow) and for the push rods and connecting arms to now be mirror images of each other. This works, because if you push down the far lever (which is the same as previously) then it now turns both connecting arms such that the push rods are forced outwards applying the breaks, but because of the clutch it has no effect on the other break lever. If, however, you push down on the near side lever then, via the clutch, it turns the shaft anti-clockwise applying the brakes on both sides.

Not only did I manage to fit the brake system wrong on the Parkside Dundas kits I built, but it appears that I'm in good company as neither Dapol or Hornby seem to model fully correct brake gear either.

Firstly, on the left, we have what I accidentally ended up modelling. Two independent brake systems, but with the connecting arms and push rods on the near side fitted the wrong way around. This means that instead of applying the brake when the near side lever is lowered, the brake shoes will actually move further away from the wheels, which clearly is wrong. Mind you, on the right, you can see how both Hornby and Dapol model the braking system. They go to the trouble of modelling the clutch to allow either brake lever to be used to operate both brakes, but then don't bother to model the wagon wide connecting shaft, completely negating the point of fitting the clutch mechanism. I'm assuming they don't bother modelling the connecting shaft because a) it is out of sight under the wagon and b) would possibly be quite fragile, but either way they clearly weren't aiming for accuracy.

So which version am I going to add to my 3D model? Well given that there will be no difference in cost, if I can work out a sensible way of modelling the clutch, then I'll probably model all three correct versions. This way I can print which ever I want depending on what time period I want them to represent. This is one of the main advantages of 3D printing over traditional manufacturing; there are no upfront cost to create expensive moulds, which allow us to print variations at no extra cost.

Working Brakes

So as I previously mentioned I've been building another coal wagon. This is an 8 plank, 12 ton open coal wagon again built from a Parkside Dundas kit, painted with Humbrol paints and detailed with Modelmaster transfers.

As you can probably tell this was a lot more complex to paint than the all black Lofthouse Colliery wagon. I started by masking off the undercarriage and spraying the top red. I then reversed the masking and sprayed the bottom black. Unfortunately my skills with the masking tape weren't perfect so I used small pots of matching paint to touch up those areas were paint had leaked under the tape. Once this was completely dry I then painted in all the metalwork detail on the upper section in black. Which was time consuming but well worth while.

The transfers still aren't perfect; some didn't even go on straight but wouldn't move without risking tearing them, and from the photo it's clear to see there are still areas where there is air under the transfers. Clearly I'm going to have to work on perfecting adding the transfers, but when viewed from further away than the camera was it looks fairly decent and I'm certainly happy with it.

The one problem, as alluded to in the title, is that the model brakes actually work! I've obviously not quite aligned the brake detail properly and with the extra layers of paint and varnish one set was close enough to a wheel to stop it rotating unless I added more weight to the wagon. I've sanded the break block back and touched up the paint and it seems to be going round now, but I'll have to keep an eye on it and possibly file it back even further.

Yet again the transfers I used were to make the wagon appear local. This time I'm even closer to home. When I take the train to work the first place it calls is Silkstone Common before it heads towards Barnsley stopping first at Dodworth. I'm not sure where the Old Silkstone colliery was but it can't have been too far away.

Wagons In Black Satin

Having now reached the end (sorry I'll stop with the bad puns... honest) I thought I'd show you the completed wagon. As you can see it's had transfers applied, been varnished and had couplings fitted since you last saw it.

A plain wagon would have been boring so I knew I would want to add transfers but I also knew that I wanted it to represent a wagon from somewhere reasonably local. Fortunately Modelmaster produce a wide range of transfers for private owner coal wagons so there were quite a few local options to choose from. I picked Lofthouse Colliery simply because it recommended applying them to an all black wagon, which, as I mentioned before, simplified the painting. The transfers were easy to use although I'm not entirely happy with how they went on. The raised areas of the wagon tended, in some places, to trap air which I couldn't remove no matter how hard I tried.

The final step (other than sticking on the couplings which is the work of a moment) involved varnishing. Varnishing serves two purposes. First it protects the paint and transfers from wearing off when the model is handled, but it also reduces the shiny surface left from the gloss paint (which is needed to help the transfers stick properly). As with the primer and paint I used an aerosol of Humbrol satin varnish. Whilst it was easy to apply (easier than the paint anyway), I'm a little disappointed that in a few places it has left little white dots. It's unclear exactly what has caused this although a little research on the web suggests that I may not have had the varnish warm enough and well mixed.

I'm fairly happy with the result and I've learnt a few things which I can apply to the next model I build and paint. I have an 8 plank, 12 ton coal wagon (also from Parkside Dundas) that I'm in the process of putting together. This will be a slightly more complex project as it won't be painted black.

Paint It, Black

Having left the primer to dry for 24 hours I moved onto the next stage of construction and painted the wagon. For this first attempt at modelling I made life easy for myself by painting the entire wagon black. This meant I didn't need to bother with masking tape etc. but as you will see in later posts this will still lead to a historically accurate wagon.

Just like with the primer I used an aerosol can to paint the wagon. Whilst this was easier than applying the paint with a brush it wasn't as straightforward as spraying on the primer. The paint is thicker and I thought it was going to obscure a lot of the detail. Now it's dry I'm fairly happy with the level of detail, but I had to give it at least three coats to get a proper covering of paint.

It's difficult to see in the photo but I used a gloss paint. While I don't want to end up with a shiny model, I'm intending to use waterslide transfers to detail the wagon, and these are best applied to a gloss surface, as you will see in the next exciting instalment!

Priming The Wagon

Having assembled the Parkside Dundas kit of a 7 plank, 12 ton open coal wagon (see this post) the next step was to prepare it for painting by weighting the wagon and priming the surface.

Whilst I don't want the wagon to be so heavy that it can't be pulled or pushed along the track it does need to be heavy enough to ensure that it stays on the rails. The plastic kit is very light and when pushed around my layout (I was using the Pug to push it) it would derail at every set of points. Essentially the bumps in the track cause it to lift clear of the rails and when gravity takes over, more often than not it doesn't return cleanly. When I was younger lightweight models were made heavier with big chunks of lead -- my model of Flying Scotsman has a big chunk in the tender. Unfortunately lead isn't really good for you and so the powers that be have made it difficult to buy. Fortunately there is an alternative that is actually easier to use.

One of the problems with using lead to weight a model was finding somewhere to put it. As I haven't yet decided if I want to model the wagon as full or empty I don't want to put a weight inside it. This means any weight has to be added underneath where there isn't really much space. The modern/safe alternative to lead is Liquid Gravity (I can't find a sensible page from the manufacturer so I'm using the page from my local model shop where I actually bought some). Essentially Liquid Gravity is lots of very small yet heavy metal balls that easily flow and fill small areas and holes which you seal in place using superglue. Given the layout of the underneath of the wagon it was easy to add quite a bit of weight without affecting the appearance.

Once weighted down the next step was to use primer to ready the model for painting.

As you can probably tell from the photos I'm using an aerosol can of Humbrol grey primer for this job. Having never tried to spray paint anything before I'm actually quite happy with the result. It took almost no time, compared with doing it with a paintbrush, and it's a much more even coat than painting would have produced. The only downside being that I forgot to mask off the brass holes for the wheels so these will need cleaning up before the model will run smoothly but that shouldn't be too much of an issue (I hope).

The next step will be to paint the wagon.

12 Tons of Coal

While you can build a model railway using just off the shelf ready-to-run locomotives and rolling stock, there are plenty of kits available that allow you to expand your railway in interesting ways. As I mentioned in a previous post, depending on the time period I choose to model I might have to at least re-paint some ready-to-run models even if I don't have to resort to building kits.

My previous experience of building kits was with Airfix aeroplanes as a child. While the models usually went together alright the painting and finishing usually left a lot to be desired. Given this I decided it was probably sensibly to buy a cheap kit to see if my skills had improved over the years before possibly moving on to building expensive locomotive kits.

So my first real foray into railway modelling is a 7 plank, 12 ton coal wagon using a kit from Parkside Dundas. This design dates from 1923 and so doesn't quite cover the entire period I might wish to model, but it's a good starting point. As you can see so far my progress is okay. It still needs some cleaning up (including levelling the buffers a little looking at the photo) and then it needs weighting (it's so light if I try and push it around the track it jumps off at every set of points), some gaps filled with putty, priming, painting, transfers applying, and finally varnishing. In other words there is an awful long way to go yet so you can safely expect a few more posts as hopefully it turns into an acceptable model.