On30 Railbus

[Huw Griffiths]

I wasn't joking when I suggested that the Xmas TV was so dire that it drove me to modelmaking. Well it's certainly fair to say that, any moment I haven't needed to be elsewhere over the last few days, I've been desperate to get away from the telly and return to the cutting board.

 

 

Here's my first scratchbuild (well the first one I'm likely to complete, anyway - though I have built a number of part models, to test concepts). I'm building a generic, semiscale, On30 Wismar "Hannover" type railbus. The body's scratchbuilt  (but uses some modified / repurposed parts) - the chassis uses subframes from a Hornby Class 142 Pacer.

 

As a "taster", here are some photos - taken at various points over the last few months (most in the last 48 hours) - showing progress to date. As I'm hoping to do further work on this model in the next few hours, I hope you don't mind if I post some photos now - and further photos and comments later. I'm sure there will also be some adjustments - ride height - weights etc - I'll also deal with them when time permits:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Anyway, that's all for now - there will be more photos etc to follow.

 

In the meantime, back to the cutting board.

 

 

Huw.

[Huw Griffiths]

Further progress - this was the state of play 20 minutes ago:

 

 

 

 

 

There's no doubt that this model will get finished - but it's likely to be a while before I post further photos. I certainly won't be rushing this build - I'd prefer to do a decent job.

 

 

Huw.

[N15class]

Looks an interesting project. I am just wondering why the none powered wheel is pivoted?

[ColinK]

Ingenious use of a Pacer chassis. Looking forward to seeing the finished railbus.

[Huw Griffiths]

Many thanks for your kind comments.

I'd also wondered about the pivoting business myself.

I'm using the chassis parts from one of 2 powered cars in an early OO gauge Hornby Pacer set - which features this arrangement. I'm guessing that Hornby were expecting some of these "models" to be run over "toy train set" curves - probably with reverse curves thrown in, for good measure - so they might have been trying to stop them falling off the track.

I actually had a bit of "fun" with this aspect of the chassis. The motor and trailing subframes have different heights - it took me a while to work this out - I'm still not convinced that I've got exactly the right amount of packing where the trailing axle subframe fits - but I think I probably want something around 70 thou' (1.75 mm). I reckon that more experimentation is called for - thankfully, I'll now have all the time I need to get it right.

To be honest, I'm mainly using this chassis because I've already got it - and it was very cheap - thanks to a previous owner completely "butchering" a wiring job on it and damaging the bodyshells and chassis frames in the process. Of course, none of this worries me too much, as the moving parts work just fine. My background means that I'm also quite happy using a soldering iron (actually something of an understatement - I'm glad of an excuse to use a soldering iron).

Of course, this means that I've got another of these chassis available (and more, if I see other similar chassis at similar prices) - I'd quite like to sort out this issue, plus or two others, so I can then think about what I'd like to build with the remaining chassis. I'm not convinced by the "Wickham RB3" railbus (shown in the second of my photos) - mainly because of the narrow window pillars and low roofline (relative to the windows).

I know that there were loads of variants of the Wismar railbus design - different lengths - widths - wheelbases - seating arrangements - roofracks (on many) and / or racks next to the engines. All of this might allow for the possibility of different, but basically similar, models - which probably wouldn't cost too much to build - but I'm not sure if I'm looking to build more than one example of essentially the same model. Time will tell.


Anyway, changing the subject, your builds look excellent - it'll be interesting to see what other people think.


Regards,

Huw.

[Huw Griffiths]

This is probably a good point for me to say a bit more about what I was trying to do - what's actually been done - what remains to be done - stuff like that.


THE STORY SO FAR

A number of people are happy to shake RTR models out of boxes - possibly add a couple of transfers or spray a bit of Dullcote on their new acquisitions - but basically leave them much as they started. I'm sure we've all done this - probably still do - and there's nothing wrong with this - but, attractive as some RTR models might be, I'm not convinced that "box shaking" offers much of a sense of achievement.

I'd been thinking of building my own loco or railbus model for a while - I have built some "proof of concept" part models but I've never completed a scratchbuild in my life. In other words, I'm definitely not an experienced scratchbuilder. For me, DIY gear meshing, intricate valvegear and other "statement" model stuff were definitely off the menu - I wanted something I (or anyone else) could build without too much difficulty, without a large workshop full of specialist tools. I also wished to be able to use a cheap, readily available, RTR chassis - readily available plastic kit parts - plus other stuff I could produce myself using standard materials and cheap stuff I could easily adapt.

Having spent a large chunk of my life working in higher education, I'm also keen on the idea that somebody else with limited modelmaking experience would be able to build something very similar, in the highly unlikely event that they actually choose to. In other words, I was looking for something straightforward to build, which could yield a reasonably satisfying model.

I'd actually had some project ideas buzzing around in my head for a number of years. I can remember one thread on FreeRails, in which one site member had posted photos of a homebrew railbus he'd built in a similar scale - I liked the end result so much that I joined the site. In discussions later in the thread, I happened to mention Wismar railbuses - and he responded by very helpfully posting a link to the online archive of the magazine "Die Museums-Eisenbahn". I found the information and pictures in various issues of this magazine extremely useful.
 

 

I'd also been considering other ideas for a "motive power" build:

• One of the petrol powered inspection railcars used between the wars by the North Eastern Railway.
• A Class 151 Sprinter prototype.
• A proposed ultra-basic variant of what became the Pacer railbuses ("RB3" - from a Wickham-branded sales flyer shown on a number of websites).
• A Polish MBxd-2 narrow gauge diesel railcar.
• Various designs of tramcar
• An AGEIR boxcab
• A Köf.

In the end, I decided against all of these, as I didn't feel that I had good enough drawings to work from.

I also briefly considered some freelance concepts - a small railbus - and a "critter" loco - both built onto Bachmann "Underground Ernie" multiple unit chassis. I've got no doubt that it would not have taken long for anyone to throw together either of these creations (the railbus certainly wouldn't have taken me long, since I'd already developed an almost complete set of detailed, "model size", drawings for it in Illustrator) - but I was really looking to build something rather more credible.


This left me looking again at the Wismar railbus. I'd come across a rather attractive set of elevation drawings in a book about railbuses, by the late WJK Davies - so I scanned these drawings into my PC - and opened them up in an old version of PhotoShop.

Somehow, I'd managed to scan them in square enough to work with them - but I soon discovered another issue which plagues anyone trying to work from drawings in books - the drawings had been reproduced to different scales in the horizontal and vertical axes. After giving my calculator a workout, I entered appropriate scale factors into the relevant "boxes" in PhotoShop did a bit of "cleaning up" on the resulting file - and all was soon well.

At this point, I probably should have converted the drawings into paths - and taken them into Illustrator. Unfortunately, lots of calls on my time meant that I didn't have chance - but this is something I intend to do in due course.


You might have noticed that a sliderule made guest appearances in some of the photos - it's included to give some idea of scale - despite being German, the scale running along the top of it is actually marked in inches!

 

I've mentioned elsewhere that I acquired a number of sliderules in one of those legendary "free to a good home" deals. This might suggest to some people that the things have no practical uses and should have no place in any modeller's (or engineer's) workshop. I would suggest otherwise. I'm not trying to pretend that I use one all the time - but, if you're trying to scale drawings (or multiply / divide a load of dimensions by the same factor) it's easy to set up a "look-up table" on one of these.

At this point, I should perhaps explain the odd choice of scale for my model. Wismar railbuses are German - so a lot of modelmakers would initially think of building one of these in Oe (1:45 scale - but still on 16.5mm track). I'd considered this, but thought it might make more sense to build in a scale in which it would be possible to get the engine hoods in plastic kits.

The original design of the Wismar "Hannover" type railbus used the drivetrains, engines and hoods from two Ford AA light trucks - these were fitted to a lightweight welded steel chassis, with a boxy bodyshell between them.

Some people will know that the Ford AA light truck was also made under licence in the Soviet Union - as the GAZ AA. In later years, GAZ produced a number of variants of this basic design - AAA (3 axles) - MM ("stripped out" wartime version, with some other changes). Large numbers of these later versions were built and used during the war (and a few years afterwards).

Although I haven't seen kits of the Ford trucks, I have seen plastic kits of the GAZ versions - from a number of manufacturers - in a number of "military modelling" scales (1:35 and 1:48). Despite not planning to use two of these kits when building my model, I didn't want to close the door on this possibility - so On30 it was.


There was also some logic behind my choice of chassis. I could have opted for a High Level (or similar) chassis kit - I probably will for some future projects - but I thought it might be interesting to see what could be done using a cheap RTR chassis (especially one I already had in my possession).

A while back, while visiting a model shop, I'd come across a Hornby Pacer set - both cars powered - on which somebody had done a disgusting wiring job (they'd also hacked bits out of the bodywork and interior). None of this worried me, as all the moving parts worked just fine. What I had in front of me was the fully functional "guts" of two 4 wheel chassis, at a price I would have been mad to refuse.

 

Anyway, I've been into electronics for most of my life - and I've also done a lot of strain gauge wiring in the past - so doing my own wiring job (to a high standard) is never likely to cause me any problems.


Returning to my railbus build, I was trying to avoid manually transferring all the drawing dimensions to plain sheets of styrene, so I printed out several copies of the drawings. I then used double sided tape to stick the plan section of one of these to some thick black styrene sheet. Some cutting, drilling etc. followed - after which I fitted the Hornby Pacer chassis subframes to my new chassis plate - this was when I discovered that packing was needed above the trailing pony truck subframe.

Although sticking a paper template to styrene sheet allowed me to cut outlines to shape, at the ends, a number of cutting / marking lines converged at sharp angles. Here, I found that the paper template moved about when I tried to cut through it. Further attempts with different types of tape didn't really cure this problem - but left a sticky mess on the styrene sheet, which I had great difficulty removing.

I also realised that the top of my chassis plate was higher than the floor - and the chassis members below the engine hoods - should be, so I then produced a new chassis plate from thinner styrene. This time, I had no choice but to transfer all the dimensions manually. From the photos, you might notice that I did this by lightly scratching the surface with the tip of a scalpel - running a marker pen over the area - and then using an eraser - leaving only the lines visible.

Here's where I missed a trick. The styrene I used for the new chassis was thinner, softer and easier to cut than the black styrene I'd used for my original test - unfortunately, it also flopped about more than I might have liked. I actually had some other styrene sheet - of the same thickness - but a lot stiffer - but I didn't think about using it until was too late.

For various reasons, I was keen to get as much as possible built on this before the end of 2015. Unfortunately, I also had lots of other calls on my time - so some things got rushed - and others didn't get done at all. I'd imagine that some stuff might get reworked - but time will tell.


When I studied drawings - and photos - of the real railbuses, I noticed that the chassis involves a mixture of steel sections (some with holes and slots) and a truss framework. Rather than try to copy every last detail of this, I just tried to use what's visible to create a general impression. Here, it helped that I had some heavy section solid styrene strips and some I beam sections. This also allowed me to stiffen the chassis and provide some hidden reinforcement below the noses / engine hoods - when I cut the chassis plate to size here, the visible "engine support beams" will be for appearance only.

The next step was to raise the edge of the chassis to the top of the motor bracket - further stiffening the chassis - providing a tray into which I can stick weights as needed - and allowing me to add a completely flat internal floor (with seats). Well, that was the theory. In practice, I was using whatever Microstrip was to hand. The edges were lower than they should have been - and I ended up having to use paper labels to pack the edges up to a more suitable height.

This "tray" doesn't have corners - they're not needed with the type of weights I'm using - that and the fact that the railbus body has rounded corners, so I needed to allow for this. This also explains why I rounded off the corners of the false floor - essentially, a rectangle of thin, black sheet styrene.

Now I come to the seats - these were adapted from the interior moulding out of a cheap OO gauge coach - a YMRV "British Rail Mk.1" corridor third. I chopped the moulding into individual "back to back seats" sections - removed any traces of the original floor - and chopped the seats to the required length.

Finally, I stuck the seat moulding sections to the false floor.

 

Incidentally, the "open" ends visible on the outside of the seats won't be an issue in the completed model - they'll be hidden by the external saloon walls of the bodyshell - sealing the ends would actually have caused far more problems, as this would have trapped solvent vapour between the seats and the floor.

 

The Wismar railbus has a boxy bodyshell, with rounded corners - and the windscreens slightly raked. To represent the rounded corners, I used some sections from the body of a cheap torch - other options would have included barrel sections from a cheap ballpoint pen, or building up and filing / sanding layers of styrene. I then stuck some styrene strips between the corner sections.

This is as far as I got before the end of 2015.


WHAT HAPPENS NEXT

The next step will be to file the rounded bodyshell corners back above the waistline, to represent the rake of the windscreen. The sides of the bodyshell are basically flat rectangles, with rectangular cutouts for windows. I'll also need to recess the doors (most of these railbuses were fitted with sliding doors). I'm thinking in terms of fitting strips of angle section - to the top of the sides and ends - and dropping the roof in from above.

As for the ends, the most visible parts will be the engine hoods. Here, I'll have 2 basic options:

• Using hoods taken from 2 military model kits of GAZ trucks - although the easy option, this also happens to be rather expensive.
• Building my own homebrew hoods, from scraps of styrene. This is likely to be a lot cheaper - and probably not as difficult as it might sound. Although the classic image of this type of railbus features 2 truck hoods, a number of these railbuses were fitted (or retrofitted) with hoods to much simpler designs - often essentially boxes with slab sides, rounded corners and vents / grilles as needed. These would be easy to reproduce in model form.

After fitting the hoods, I'll then trim the ends of the model's chassis plate to a suitable length and shape. This will be followed by flipping the model over and adding suitable bits of styrene to represent the beams which support the engine in the real railbuses.

Finally, I'll look at details - axleboxes and axleguards ("W irons") - leafsprings - lights - stuff like that.

In other words, there's a significant amount of work ahead - and some stuff still to work out - but I have every confidence that I'll be able to finish it.

However, I also know that there's now no reason for me to rush. In fact, right now, it's better if I don't rush, because I've got a bit of a cold and I'm tired. I'll finish this project when the time is right - when I feel able to finish it to standards I am happy with - and if this requires any reworking, then so be it.

 

Regards,

Huw.