NZRedBaron's thread of questions

[NZRedBaron]

Hey all; I'm going to be ordering some Chivers kits (their LNER pigeon brake van, for the record) for a first attempt at model building, but I've just realised a problem that I might have; that being, how do I go about fitting the sides and ends of the van to the floor, without them bowing outwards and leaving big panel gaps?

Should I stick some blocks of something like polystyrene or balsawood into the corners, to act as reinforcements? What would you all suggest?

[Atlantic 3279]

As I remember it, when I built mine a few years ago the parts required only a light clean-up to produce straight and square edges giving a very good fit. The the assembled structure, with all the seems bonded using solvent adhesive, was sufficiently self-supporting to need no extra bracing to avoid distortion.

[NZRedBaron]

Sounds fair enough; but how about during the actual assembly stage while the glue is drying/curing/whatever the term is?

[Dave S]

Sounds fair enough; but how about during the actual assembly stage while the glue is drying/curing/whatever the term is?

That takes just a few seconds.

When wagons are made up they make a box structure which has its own rigidity. Your best bet is to dive in with. knife, glue and files and see how it goes.

[Atlantic 3279]

Dave got in first while I was typing this:

You may be imagining a problem that does not occur. The tendency, if any, with plastic box structures, is that the solvent-welded corner and edge joints try to tighten up to an acute angle rather than staying square, "sucking" the sides in rather than bowing them out. The combination of adequately thick / stiff sides, the way the sides and ends fit around the straight edges of the floor, and the way they gain extra support from the straight edges of the roof (which may have a lip / rebate arrangement) prevents the distortions in a well designed kit. I believe your kit has those features.
If no hole in the floor is provided, you perhaps ought to drill a breather hole in it, just in case you manage to make all of the joints perfectly air-tight, unless you want a box tries to respond to changes in air temperature and pressure.

[Hatfield Shed]

Sounds fair enough; but how about during the actual assembly stage while the glue is drying/curing/whatever the term is?

I feel that either you may not have assembled a plastic construction kit, or if you have it was long in the past?

Some of what follows has already been alluded to, but it is well to clarify.

The ideal assembly method is by use of a liquid solvent 'cement', which is applied by means of a small paint brush to the joint line of the components in contact: ideally on what will be a concealed location when the model is complete.

First check the fit of the components in a dry run, and only when content that the fit is good apply the cement.

The cement runs along the joint by capillary action into the small gap between the jointing surfaces, and as it is a volatile solvent, swiftly evaporates resulting in a rapid bond.

Nothing else should be in contact with the joint line as the solvent is applied, as this will potentially mar surface finish, the solvent will go everywhere there are small gaps by capillary action.

If you use a small brush for the cement application the bonds will be relatively weak. This is actually desireable at first assembly, as if there are any small errors adjustment is possible. Once the basic 'box' is assembled and true, a second larger application of solvent may be used for greater bond strength.

I do not know what brands of liquid cement may be available to you. For regular polystyrene I favour Slater's Mekpak, and for ABS formulations Butanone.

[jwealleans]

I was going to mention solvents - MekPak or similar will grip the joint almost at once and can be used to build a plastic wagon kit completely in a very short time. Something like Limonene, however, needs much longer to grip and set, so is no use if, say, you're demonstrating wagon building at a large and well-patronised show. Guess how I know that?

In either case, you won't see the distortion you're referring to with either of these. Chivers kits are as good as it gets. I'm almost tempted to suggest starting with something else as whatever you build from other ranges will always be more or less of a comparative disappointment after this start. But at least you'll know it's not you, it's the kit.

[NZRedBaron]

Fair enough; for the record the last couple of model kits I tried to make were 1:72 Airfix Spitfires many years ago; even following the instructions and using modelling tape to hold the parts together while the glue set, a massive gap opened in the seams along the whole length of aircraft, from nose to tail- only thing that held it together was the tail, wings and the cockpit canopy; didn't matter if I was using Tamiya liquid cement or... whatever that brand is that comes in the blue metal tube?

That being said, it might have been because I have thick, massive hands that aren't actually all that flexible or dexterous. Either way though, much food for thought.

[NZRedBaron]

Another thought that I had just now; if I discarded the guard's ducket off the model, could I fake it up as a CCT van or something similar?

[Atlantic 3279]

I can well remember the agony of using squeezy-tube, slow setting polystyrene cement on distorted mouldings of aircraft parts from Airfix and similar makers in my youth, so I understand your concerns. Avoid that sort of glue like the plague, if you possibly can. Don't worry though. If you can get a very free-flowing, brush-on, fast evaporating solvent for bonding the parts together, you won't have to hold the parts or clamp the joint together for hours until it sets, and the parts in model railway kits are much more likely to want to stay straight.
If you can't get a very volatile brush-on solvent, as a last resort you could use rapid-setting runny superglue, with extreme care, but joint alignment before the glue is run into the joint is critical as you won't be able to adjust it afterwards, and the risks of sticking your fingers instead of the model are obvious. Superglue will also ruin the outer surfaces of parts if you let it get onto those, as well as often having an annoying "brittle" quality of its own, such that some joints simply fall apart when subjected to a shock.

[NZRedBaron]

If you can get a very free-flowing, brush-on, fast evaporating solvent for bonding the parts together, you won't have to hold the parts or clamp the joint together for hours until it sets, and the parts in model railway kits are much more likely to want to stay straight.

Would Tamiya cement (the stuff from the hexagonal glass bottle) work for that?

[Atlantic 3279]

That looks like the right sort of stuff, although I haven't tried Tamiya myself. Does anybody else have experience of it?

[Graeme Leary]

A very helpful tip I got from another forum member (Humorist) was to get a largish piece (about A4 size will do) of 'float glass', preferably 10mm thick but 6mm will do and assemble the sides and ends on this. This ensures the bottoms are square and match up correctly provided the bottoms are on the same level. If the ends are longer than the sides - such as including the buffer beam - (headstocks???) this is reasonably easy to line up by eye. All this is to ensure when the roof is fitted it is a snug fit with no gaps between the underside of the roof and the sides or ends.

Humorist also recommended a very good adhesive, Micro Weld; easy to apply with a brush and seems to have as much adhesion as the CA glue I previously used (and nearly asphyxiated myself doing so). This avoids the 'stringing' effect that occurs with tubes of UHU glue. If you're near South Auckland Micro-Weld is available from The Model Room, Papakura (when they reopen after the current 'lockdown).

I too am recently new to kit building and so far have managed (reasonably) successfully a number of Parkside and Slaters kits.

Graeme Leary
(Clevedon) New Zealand

[NZRedBaron]

I'll keep this in mind; also, would OHP transparency work for the glazing in the toplights?

[NZRedBaron]

Say, I don't suppose anyone has any unassembled pictures of the interiors of the ends and sides from the Chivers pigeon brakes, do they? I wanted to see if there's any grooves or tabs that the pieces slot into for assembly.