Monday, June 30, 2014

How Many Rivets?

So having realized that there were some problems with the design of the brass upper for the Rhosydd slate quarry rubbish wagon I'm building, I reworked the template and had a second go. This time the template took into account the extra width added by the thickness of the metal when folded, as well as being re-worked to make it easier to fold. This second template works really well and I was able to easily cut out and fold the brass to shape. A small amount of superglue and the whole thing was assembled; from sheet brass to assembled model was about five minutes.

Given that I was happy with how this one had turned out I decided to add the rivets that are quite prominent on the prototype. Amazingly the Archer rivet transfers (sheet AR88025) I bought for detailing the Quarry Hunslet are a perfect match with exactly the right spacing. The only problem is just how many rivets there are to apply to such a small model. I think I added 26 strips totalling 238 rivets, which took the best part of two hours to apply. Time well spent though as I think the end result looks great. The next step will be to spray it with a red oxide primer to fix the rivets in place and to give a nice rust coloured base coat.

Saturday, June 28, 2014


As I mentioned in my previous post I've been working an a whole bunch more wagons one of which will require the upper part to be made by hand as it is too fine to 3D print. Specifically I'm working on a Rhosydd slate quarry rubbish wagon using a drawing from the Lewis and Denton book. This wagon has a wooden underframe very similar to the slab wagons with a three sided iron body to hold the waste. Unfortunately I can't find a photo that I can show you of a complete Rhosydd rubbish wagon, but you can get the general idea from this photo, while a photo part way down this page shows a rusting upper body.

So far I've generated the 3D model for the underframe as you can see from this render. The wheels will attach in the same was as the slab wagon using axle retaining clips.

I haven't ordered a test print yet as I'm going to wait and order prints of all the wagons I'm currently working on at once, but I'm not expecting any issues given how similar to the slab wagon the model is. Having said that I'm not as confident about producing the upper body, although I have now made the first prototype.

The reason I can't print the entire model is that the minimum wall thickness for the material I'm using is 0.3mm. Walls that thin though are quite brittle, and as 0.3mm represents approximately an inch at 4mm to the foot scale, it would obviously produce walls that were too thick to represent sheet metal. I'm intending to solve this problem by modelling the sheet metal using ... sheet metal.

The photos show the progression from raw materials to the assembled prototype. Essentially I draw out a pattern on the computer based on how I wanted to fold up a single piece of metal to form the body (minus the rivet details). A printed copy of the pattern was then stuck to a sheet of 0.12mm brass before being carefully cut out using scissors; the tin snips unfortunately have serrated blades meaning that they aren't any use as they leave crinkled edges on the metal, although they are good for cutting sheet sections etc. a cheap non-serrated set are now on order. The fold lines were then scored using a scalpel and then any remaining paper was peeled off and the metal cleaned to remove the glue.

The upper body was then formed using my hold-and-fold. I was going to simply glue the corners but I'd not taken the thickness of the sheet into account when designing the pattern so had to resort to soldering to keep the corners together. Soldering was fairly straight forward; I tinned one side then held the joint closed with a bulldog clip before applying the soldering iron. As the solder in the gap melted the clip pulled the corner tight and once cool left me with a nice join that just need a little filing.

The result is pretty good. It isn't an exact replica as the original is made of angle iron with separate sheets for each face but once I've added rivet detail and filled the body with some rubbish it should look pretty good. I'll tweak the pattern slightly to take the material thickness into account and make up another one and then add some rivets before painting. When I eventuall get the underframe printed I should just be able to stick the two halves together.

For my first attempt at designing and building my own model from sheet brass, and my first ever attempt at soldering brass sheet I'm really happy with how it's gone so far.

Wednesday, June 25, 2014

Atmospheric Spare Parts

While so far I've only painted one of the 3 bar slab wagons I recently designed, I actually had quite a few more printed; mostly because printing more than once at once is cheaper due to their small size. Given that I had quite a few I thought it would be useful to see what other people thought of the model, and not just through photos, so I posted a couple out to two fellow bloggers. One of those was Iain who has responded with a blog post which is well worth reading, especially for the wonderfully atmospheric shots of the painted model.

All the feedback I've received so far has been positive although it has led to a few changes to the model. Firstly there was a suggestion that the main cross bars weren't quite wide enough as they don't hang out over the wheels as far as they do on the prototype. I think part of the problem here is that the 9mm track is wider than it should be if the wagon is modelled at 4mm to the foot, so even though the wagon might be the right width it won't "look" right. So I've lengthened the bars by a few millimetres to improve the look slightly. The second piece of the feedback was one I should have realised myself; supply spare parts!

As you can see in this photo the sprue containing the four axle retaining clips is tiny. Each of the four clips has to be cut from the sprue and then clipped to the axle. No matter how careful you are there is a good chance that at least one of them will go pinging off across the room never to be seen again. Supplying a spare on the sprue adds almost nothing to the printing cost so the new sprue will contain five clips.

Now I know that not everyone thinks 3D printing is good enough to produce detailed models, and that the only way to get very good results is to hand craft a master which can then be used for casting. While I agree that 3D printing isn't suitable for every model (see below) I think it works well for this one, and for most models that are predominately wooden where graining in the print isn't such an issue. One of the real benefits of this approach is that when changes are necessary they can be made without any additional expense other than my time as there is no master to alter or re-make and no molds that need to be reproduced. From a distance I think many people would be hard pressed to tell you how most models were produced anyway!

Having now successfully proved that this approach to modelling inside framed wagons works well I've started on designing a few more models. In fact I'm currently working on three new wagons. Two of these will be produced in a similar fashion to the slab wagon (all 3D printed with one main piece and axle retaining clips), while the third will require something slightly different as the upper body contains elements that are two fine for 3D printing. My current plan is to 3D print the main frame and axle clips and then to fabricate the upper section from brass sheet which will be an interesting exercise given that the only experience I have of working with it is the few etched kits I've built recently. I'm hoping I can design something that can be just cut out and folded up without requiring etching but we shall see how that goes in a future post.

Saturday, June 14, 2014

I am NOT Modelling the Welsh Slate Industry!

I am NOT modelling the Welsh slate industry.
I am NOT modelling the Welsh slate industry.
I am NOT modelling the Welsh slate industry.

Right, now that is out of the way I can show you my latest 3D printed item of rolling stock.... a 3 bar slab wagon as often found in Welsh slate quarries.

I don't have a specific use or back story in mind for this model as I can't think up a good reason why you might find one in a small factory in Yorkshire. My reason for designing and printing this model was so I could have something small, and hence cheap to print, which would allow me to experiment with inside frames.

So far all the wagons I've printed have had the frames and axle boxes on the outside of the wheels. This makes them easy to assemble as the wheels just slot into dimples on the back of the axle boxes. With frames inside the wheels I needed a different approach. I could have just printed the model in one piece but that would have meant removing a wheel from the axle so that I could slide the axle through the model. While this is possible it would mean I would have to get the back-to-back gauge correct when I put the wheel back. Instead I opted to print the model as multiple parts.

Essentially I have the frame separate from the holes the axle will pass through (four of these are printed on a single sprue) which means I can glue the parts together to trap the axles in place. A small amount of the outside of the hole is present on the frame allowing for easy and accurate positioning of the parts. Also, because over half the hole is on the small part they clip over the axle which means they stay nicely in place while the glue dries.

The accuracy of the 3D printing process means that the parts are a perfect fit, and amazingly everything runs nice and freely and having filed down the pointy ends of the axles I think it looks quite good, although I'm not entirely convinced by the paint job. The only problem with the model is that there is no where to add extra weight so it is too light to use. The solution to this would of course be to add weight by adding a nice slab of slate, but unfortunately that isn't something I can easily source locally, well not without buying a huge bag from the garden centre.

As usual with my 3D printed items, if you happen to want a 3 bar slab wagon then they are available via Penistone Railway Works.

RNAD Crew Van: Reasonably Well Maintained

So the last stage of building the RNAD Crew Van is to paint the body. Given the rather distressed state of the loco most likely to be seen pulling it on my layout I knew I couldn't do a pristine paint job, but I also didn't want to go for a very run down look so I've attempted a kind of in between, reasonably well maintained look.

The weathering is a little more obvious in real life but essentially I've used small amounts of rust wash to help pick out the door recess, the joint with the roof, the bottoms of the window frames and along the bottom edge of the wall where it meets the underframe. I then toned down the roof with some smoke weathering powder, before using dark earth weathering powder to add some grime part way up the walls all of which was then fixed in place with a waft of satin varnish.

The final stage was to glaze the windows. This actually turned out to be much harder than I expected, as four of the windows were too large for my usual approach of using Micro Kristal Klear. Instead I had to cut some clear plastic (an off-cut from laminating something smaller than A4) to fit the window opening. I wanted the glazing to be flush to the frames rather than just placed inside the walls which meant they had to be an exact fit which took an awful lot of time, so much time that I resorted to using the Micro Kristal Klear on the smaller windows.

Other than couplings and a crew the van is finished, and yet again it was a wonderful kit to build, thanks Narrow Planet!

Friday, June 13, 2014

Tool #3

Unlike the hold-and-fold I talked about in a previous thread this tool didn't cost me anything as it was included as part of the kit for the RNAD crew van I'm currently building. It is, however, a very useful tool.

I mentioned before that the body of the RNAD crew van fitted into two slots in the 3D printed floor. This tool is provided as part of the fret of etched parts to allow you to easily check that the holes are fully opened out so that the body fits easily. Once you have done this the instructions say you can discard it, but I realized that it would be extremely useful for something else.

The end of the tool is pretty much the same size (width and thickness) as the end of the Greenwich couplings. This makes the tool ideal for checking that the slot for the coupling is fully open. I had previously been using an off cut of the etched fret the couplings come in, but this was a bit fiddly and had led to me cutting my finger, but this tool works perfectly on my recent 3D printed wagons so I'll definitely be holding on to it.

Thursday, June 12, 2014

RNAD Crew Van: Upholstery

So I know I said the next step was to form the roof, but I managed to forget to take any photos of that stage and now it's attached to the body it's difficult to show you anything interesting. I can tell you that the curve of the roof was formed using the scalpel blade handle and rolling the roof between the handle and my naked thigh, I found the trousers were getting in the way! So with that horrid image implanted in everyone’s mind let's move onto painting.

I'm guessing that the floor of the original van was probably just the bare metal, but as the 3D print had ridges (a side effect of the printing process) running across the width of the floor I thought I'd paint it as a well worn wooden surface using the second approach I tried recently. This seems to have worked really well and I finished off the painting with dirty brown upholstery on the benches. Most of this will be invisible when in use but I think it looks pretty good.

Tuesday, June 10, 2014

Network Rail's... Helicopter!

If modelling the current UK rail network is your thing then you might find this an interesting prototype to add a little variety to your layout.

This was photographed this morning from our bedroom window. Initially it was hovering and I would have got a decent (in focus) photo but by the time I'd grabbed the camera it had started to move. Strangely it wasn't hovering over the railway (which is at the back of the house) but somewhere off to one side which is why I could see it out of the front bedroom window, so I've no idea what it was actually looking at.

Apparently this particular helicopter, call sign G-NLDR, was introduced as part of a new contract that started on the 4th of December 2013 and which runs for five years. It would certainly add something different to a modern image layout.

RNAD Crew Van: Body

Having struggled slightly with building the simple underframe, building the body of the van was nice and straightforward.

The body is formed from two etched pieces as the door end is slightly narrower, so you essentially form two U shaped halves of slightly different widths which then join together. Further detailing then involves the hand rails at the sides of the door (etched pieces) and door handles (the etch contains a hole which I opened out slightly to take some brass wire).

Once completed the body then simply slides onto the underframe into two retaining slots which form the opposite ends of the seats to the parts I struggled with in the previous post. Next step is to form the roof and then it will be onto painting.

Sunday, June 8, 2014

RNAD Crew Van: Underframe

So having assembled the bogies for the RNAD crew van, the next step according to the instructions is to build the underframe. Following what seems to be a pattern in my OO9 modelling, the van contains a 3D printed part which includes the underframe and seats. Completing the underframe involves adding just three etched parts; two seat ends and a brake wheel. Amazingly, given the small number of parts, this actually turned out to be a quite confusing and protracted task.

Firstly I spent ages trying to figure out how the seat ends were positioned and even ended up gluing one wrongly in place before I had it all figured out. I had assumed that the L shaped part was the arm rest and wing of the seat, rather than the arm rest and the side of the leg. If I'd looked at the later parts which contain the other end of each seat it would have been obvious. Once I'd figured out the seat ends I then went to glue the brake wheel in place.

The instructions seem to suggest that the wheel should slide over the top of the spindle and go so far as to say "to strengthen the join you can also touch the tip of the spindle with a soldering iron to melt it flat against the wheel". Unfortunately the spindle is much too wide for the hole in the etched wheel. To try and make sure I didn't weaken either part too much, I slightly filed down the spindle and slightly opened up the hole in the wheel until it was a nice push fit.

It's also worth pointing out that the edges of the 3D printed part that form the sole bar are very fragile. After I took this photo I managed to damage them on two corners while trying to fit the body. While the material that the body is printed from actually glues well I couldn't find the broken off pieces. In the end I ended up cleaning up the broken area, gluing a small piece of plastruct in place and then filing it flush against the part. Once painted this should be completely invisible.

Saturday, June 7, 2014

RNAD Crew Van: Bogies

So while I wait for the next deliver of 3D printed parts to arrive so I can carry on with my wood painting experiments, I thought I'd make a start on the Narrow Planet kit for a RNAD Crew Van that I've had sitting around for over a month now. So far I've built the two bogies.

The moulded bogies are Parkside Dundas items (you can tell because the full kits and instructions are included even though you don't need anything but the bogie frames) trimmed down and tided up a little. There was a stretcher between the axle boxes that I've removed plus they have been shortened by removing a little from both ends. Rather than using the plastic brake details from the original bogie kit, some really nice etched parts are used to give a much finer appearance. The last step is to added the steps to one of the bogies.

Since taking the photo, I've realized that the plastic bogies are not entirely symmetrical in that the mounting hole isn't central along the length of the bogie. I'd managed to glue the steps on giving the longer side to the outer edge which would have stuck out from the end wall of the van. I've swapped the steps to the other end as well as removing a little more plastic to try and even things up, but there looks as if there should be plenty of clearance between the two bogies.

The next step, according to the detailed instructions, is the underframe.

Painting Wood

While I was really happy with how the wood colouring of the 3D printed flat wagons turned out it should be obvious that the colour is really only suited to newly planed wood and that in use on a railway unpainted wood wouldn't stay this colour for long. The advantage of having 3D printed the wagons is I can easily print some more and paint them in different states of repair. I currently have some more on order but before they arrive I thought I'd do some experiments to work out how I'm going to represent wood in different states of ageing.

When I ordered the first set of wagons in the finely detailed material I also ordered a set in the cheaper material I've used before for printing OO gauge wagons. While these didn't turn out well enough to be useful as models, I thought they could form the basis of a useful set of painting experiments. It is worth remembering though that as they are made from a different, much rougher and more absorbent, material that the final wagons will look slightly different.

I had two approaches I wanted to try. Firstly there was Iain's suggestion for producing a silvery grey wood colour and then a dry brushing based method that I'd read on a forum that I thought worth trying.

I started with a variation on Iain's suggestion; the variation being that I didn't have any Humbrol #27 in my paint box so I substituted Model Color's London Grey (#70.836) which I believe is a 50/50 mix of black and white. So I started with a layer of London Grey, then a thin wash of black (Model Color 73.201) before dry brushing on some Tamiya Gun Metal. I also dry brushed on a small amount of khaki (Model Color 70.988). You can see the result on the left hand model. This seems to work quite well, and I would never have though about using a metalic paint to add the aged effect. I might need to experiment with both the base grey and the amount of black wash, especially as in reality it looks a little darker than the photo, but it looks pretty good.

The second approach is similar in that there is a base colour, a wash and some dry brushing but there are quite a few more paints (all Model Color) involved. I started by painting on a layer of black (70.950) and then once that was dry a layer of khaki keeping the layer thin enough to allow the black to give slight variations in the finish. I then used the black wash (73.201) to detail the gaps between the planks etc. and to tone down the khaki. A round of dry brushing then followed using khaki followed by brown sand (70.876) and finally dark sand (70.847) which confusingly is a lighter colour than brown sand. I then retouched in the details by adding a very thin watered down layer of the black wash. The final touch was then a very light dry brushing of dark sand to lighten the raised areas ever so slightly. Obviously the effect and colour is very different to the first approach, but then it represents a different stage of the wood ageing. In fact this approach seems to match quite well with my next door neighbours unpainted fence which I think is around 10 years old.

Of course I'm not sure how well these approaches will work on the other material, but hopefully another bunch of models should arrive from the printers next week some time so I shouldn't have too long to wait to find out.

Sunday, June 1, 2014

Wagons Roll

Having now painted all three wagons I had printed, I thought it might be nice to show them in action. Unfortunately when I tried to do this I found that my lovely Quarry Hunslet wouldn't run in reverse, so I've had to strip the motion back and reassemble it. I still don't know what the problem was, and it still isn't running as smoothly in reverse as it did before. Anyway here are the three wagons being shunted backwards and forwards along the short test track.