TangoOscarMike

Very nice! I've done a lot of work along these lines, and your saddle tank is much better than mine. Also Tom

Well, that's very gratifying! Perhaps I don't know all that much. I was pretty successful with the Brassmasters kit, in spite of my sketchy soldering skills. Perhaps this will give me the incentive to reinstate some of the pictures.

It's not for everybody, but you might want to try OpenScad. I've used it for all my 3D models.

Hello Dan No, in fact I never offered the prototype for sale, only the two final versions (inside and outside cylinders). I haven't yet got round to putting the streamliner up for sale - I really must get my act together. Let me know if you'd really like it, I could make the prototype available from Shapeways with no markup (not that my markup is especially large). But for the reasons discussed in this thread I'd advise against it. In particular the long overhang at the back of the locomotive is unsatisfactory. I sometimes think of making an "old fashioned" haycock firebox version, and it's possible that the lower boiler of the prototype would be appropriate for that. Otherwise, though, the prototype has served its purpose.

Impressive! I've been generating coal "procedurally" for 3D printed locomotives, using OpenSCAD. Each piece of coal is the intersection of two polyhedra, pseudo-randomly scaled and oriented. The pieces of coal are placed on a grid (on a pre-defined surface), with random displacements from their orderly grid locations. It's not a reliable process - I must generate the coal multiple times until I have a result that is free of too-regular looking features. I wonder if I can use your approach for coal.

Perhaps "I think I now have terms of reference for my next phase of procrastination" would have been nearer the mark. Apart from buying some plastic tube for the boiler, I haven't made any progress on the locomotive. But to keep myself going I've made another coach. This one doesn't have so much glass - it's third class. I've made a bit more effort with the hand rail at the end, using two 3D printed knobs and a piece of mandolin E-string. The gap between roof and body, on the left hand coach, is fortunately not a permanent feature. I must have dislodged the roof while arranging them for the photograph.

Tom, in fact. But the confusion is entirely my fault!

That wasn't just inevitable, it was necessary. It would have be wrong not to do it!

Well, that's very pleasing indeed. You don't need suggestions, but I'm going to make one anyway. How about a fairground organ? Some of these are extremely elaborate, with many instruments and lots of the workings exposed. You could incorporate a musical box mechanism, to have it make real music, although perhaps the sound would be too tinny.

Shipmates! Somebody contacted me via Shapeways to ask for dimensions of the Holden/Pug. I produced this diagram, which is the running plate that forms the basis of all my 3D printed locomotive bodies. This was the result of quite a bit of trial and error, and my record keeping was not all that great, so I can't guarantee the accuracy and I'm not sure that all the fiddly little cutouts are really necessary. But maybe some of you will find it useful. I suggest you start with a piece of cereal box, rather than commissioning tooling for industrial scale injection moulding on the strength of this doodle alone! Dimensions are in millimetres, and my running plates are 1mm thick.

Thanks Dan I haven't abandoned this project, but I also haven't made any progress recently. I would certainly be interested in your feedback if you go ahead and get one.

It's nice to see Edward putting in an appearance.

Yes, this is precisely the problem. Abandoning the body and using only the chassis, I have tried to design cunning mechanisms to allow the required movement. But the large motor mount restricts the freedom of rotation so that (as far as I can tell from my crude mock-ups) the whole mechanism would only work on large radius curves. Yes, that would be the sane approach. But I'm currently on a (frugal? miserly? ridiculous?) quest to discover all the things that I can accomplish with the cheapest-chassis-of-all. Ah. I was going to suggest putting a bigger bunker at the back in order to move everything forwards. But I suppose that would result in the gearbox poking up into the boiler. In any case, I really like the look of it.

To my mind, the holy grail of pugbashing is to make two Holden 0-4-0s into a double Fairlie. I've made some experiments, but not much progress. So I thoroughly approve of this. But is the font bogie a little bit under-loaded in your design?

Thank you Bernard, that's an enormous help. I think I know what to do next. Also, hats off to the you of 40 years ago!

Thank you Bernard. I really like your model, and I feel inspired to make a bit of an effort, at least, to lower my model. I've noticed this in many photographs - crew whose heads are brushing against the top of the cab entrance. The height of my mock-up cab is driven by Dapol figures - I will be removing arms and legs to put half-figures either side of the motor, but I don't want to have to adjust their height if I can help it.

Thank you Keith. I think you're right: whatever else I do, I must make bigger cylinders. I've been avoiding this because when I modify RTR stock, I will go to great lengths to avoid permanent modifications (at this point in the project I can reattach the original body and the model will be unchanged). It's going to be hard to enlarge the cylinders without deviating from this philosophy. But one way or another, I must have bigger cylinders.

The last phase involved some freehand plastic cutting, which isn't something I'd normally do. So to return to my comfort zone I've made a wonky paper mockup of a body, to get a feeling for general dimensions and proportions. I'm imagining a 12mm diameter boiler - this is slightly larger, since I made it from gummed paper wrapped around a 12mm pen barrel. And the cab and tanks go all the way to the edges of the running plate, which makes the whole structure slightly fatter than planned. On the whole I think it's more or less OK. But the last picture, from the side, makes the body look over-large, perched on tiny wheels. I see a few alternative ways of looking at this: It's fine the way it is, and a normal sense of proportion will be restored when I have hardware (valances, steps, buffer beams, maybe bigger cylinders) below the running plate. I could make the whole thing a little smaller, at the expense of making it harder to cram crew into the cab. I could try to lower the running plate. This will make the whole design more complicated. I could try to lower the footplate, creating a step in the running plate. I would be grateful for your opinions.

And this is how it all goes together. The central plate lives on the chassis, and will not normally be removed. The running plate is held to the central plate with two screws from below. And that's it. It's going to be a side tank, so it'll be straightforward to accommodate all those pieces inside the body. I was considering making all this out of brass. This plastic version could have been a trial run. But this has been successful enough that I'm going to forget about the brass and just crack on.

The original locomotive body is held on with a long machine screw whose head is disguised in the dome. This is a pretty neat piece of sleight-of-hand, but a difficult thing to adapt to a freelance narrow-gauge body. This is what I've done: The central rectangle is almost cut away at this point. I've cut two plastic plates that will be glued to the main running plate, and will cover the outer screw holes. If I do all this again, I will make these two pieces a little bigger. Masking tape on the two plates and on the central rectangle. The two plates are attached to the main running plate with superglue on the masking tape only. And then glued with ordinary plastic glue to the running plate. Holes drilled through and enlarged. And now the central rectangle is finally cut free, and the masking tape discarded. The central plate put back in position and held with machine screws. And the nuts trapped in place with little plastic surrounds.

I spent a while on the internet, looking for small metric machine screws, and I even considered buying some tiny dies from a model engineering supplier. But then I found and tried a 10BA screw. And since it fits perfectly, I've lost interest in the hypothesis that it's actually something else. So here we are: I was thinking of making the running plate out of brass. But this plastic mock-up will probably become the finished thing. The strips underneath are to locate it against the chassis. The two extra holes, and the partly cut rectangle, are the beginnings of an attachment scheme based on the Gem Vari-Kit .

Thank you! I'd persuaded myself that it had to be metric, since the model is German. And it's my interests for it to be metric, since I live in Germany. I dread to think what happens to people who try to smuggle imperial hardware out of the UK, or into Germany, in these times. Bad things, I expect! As you say, it might not actually be 10BA, just close enough. I've just asked Google about nearest metric equivalents of 10BA, but of course this topic is a rabbit warren. I have an un-assembled Brassmasters Cleminson Chassis kit, which includes 10BA machine screws. Maybe I will borrow one of those. Or maybe I'll be really lucky and find that there's a spare.

The original locomotive has a threaded hole in the chassis, and the body is held on with a long screw. My starting point will be a running plate (card experiment shown here), and I need a much shorter screw, with the same thread. I thought it might be M2, and I went to my nearest model shop (mainly aircraft and boats, they don't do trains) and looked at their selection of machine screws. They had M1, M1.2, M1.4 and M1.6 - all clearly too small. M2 looked about right, but when we tried my screw in an M2 nut, it slid straight through. The man in the shop said he thought it might be M1.8 ("I don't know if anyone still makes that" he said) but he also said that in the old days many model railway companies had their own thread standards. I'll take that with a pinch of salt (maybe in the old old days...). I bought some M2 screws anyway. Still, according to Wikipedia M1.8 does exist in ISO 262. I've looked on Amazon, and found many sets of small machine screws for sale - in many cases marketed for repairing glasses. Not many of these have anything between M1.6 and M2, but those that do have something called M1.7. Tsk. If they (the people responsible for all the things in the world) had bothered to ask me, I would have advised them to keep things straightforward. It's too late now.

I agree. There are five (right?) locomotives that use this chassis in its two variants: The Holden 101, the Caledonian pug, the two inside-cylinder steam engines and the diesel. Allowing all 5 would make sense.

Well now. I had several weeks of dabbing on a little bit of paint from time to time, scowling at the result, then repeating the activity a few days later. And then I had a long summer with work bleeding into real life, odd scraps of leisure time spent outside, and very little modelling at all. A few days ago I looked at the coach again, and a remembered that it isn't a Fabergé egg, and nobody's life depends on the quality of the paint job. So I gave it a coat of varnish and declared it finished. Next came glazing, cut from some plastic packaging and secured with a few blobs of PVA around the edges ("it's the wrong glue, Gromit"). And I've decided to worry about the buffers at some future time, if at all. So now I have two coaches that roughly match in terms of dimensions and livery, and one runt-of-the-litter (roof currently AWOL). Now I think it's time to tackle the locomotive. And maybe make another coach.