Build perfect plastic kits

George Dent gives a masterclass in plastic kit construction, using a Parkside ‘O’ gauge van as an example.

Building plastic rolling stock kits can be great fun, especially when working with good quality products that feature crisply moulded parts that fit together easily. I’ve been a big fan of the Parkside range of kits since I was a teenager, building about 200 of them so far, mostly in ‘OO’, but also in ‘N’, ‘O’ and ‘OO9’ gauges

They offer great value, with wheels and bearings supplied, while the 7mm scale kits also provide a wealth of underframe fittings, sprung buffers, scale couplings and even sets of transfers. Now produced and distributed by Peco, they’re readily available from model shops.

Preparing and aligning of the parts is important with any kit, but especially with rolling stock subjects, where the chassis and body need to be built square and true in order to ensure that the wheels and axles perform correctly. A degree of twist or misalignment can lead to unreliable running and even derailments.

This doesn’t mean that the task is difficult, however. By taking a few precautions and test-fitting the parts before gluing, we can avoid most of the potential pitfalls. As shown in the accompanying demonstration, working on a small, thick piece of plywood provides a reliably flat reference surface on which to build the vehicle. It also removes the risk of inadvertently gluing the parts to a plastic cutting mat!

Choosing good quality kits is important. Kits of a lesser quality, whose moulds are wearing out, often involve hours of fettling away waste material and lots of extra work to get the components to mate together effectively. In such cases, you need a higher degree of dedication and persistence, but the joy factor can often prove elusive (trust me, I’ve been there once or twice!).

It’s worth pointing out that, although I’ve employed an ‘O’ gauge kit here, the same core principles apply to plastic kit building in any scale.

Good quality plastic kits are easy to build and offer an enjoyable experience.

1 After cutting the sides, ends and floor from the plastic sprue, gently tidy the edges of any burrs and moulding seams using a flat file. Ensure that the edges are square and true with a set square.

2 The corner joints of the sides and ends feature small rebates and these also need to be free of any excess plastic. A pointed needle file is perfect for cleaning up these areas, test-fitting the parts to check for a close fit.

3 A piece of plywood useful for aligning and bonding plastic parts as the poly cement will not damage the surface. With the floor and one end aligned with a set square, apply a small amount of cement to the inside of the joint.

5 The process is repeated by adding the other end, followed by the opposite side. Again, check the angles with the set square and ensure that the body sits squarely on the wood base without any signs of twisting.

11 Fettle and test-fit the brake shoe assemblies to ensure adequate clearance for the wheels to rotate. Open out the holes in the brake shoes for the yokes with a small drill. When happy with the fit, commit to applying the adhesive.

4 Allow a few moments for the first two parts to bond together before repositioning the floor on the plywood base. Align one of the sides carefully and apply the cement to the inside edges, again using a set square to aid alignment.

7 Something I wished I’d noticed before adding the solebars and underfloor framing is the raised ejector pins near each corner of the floor. These impede the fitting of the brakes, so they need to be flattened before you continue.

10 Insert one of the axles and position the opposite axleguard assembly. Check that the axle sits concentrically with the wagon’s longitudinal axis and that the wheels rotate before securing the axleguard to the solebar.

6 It’s wise to leave the body for an hour or two before adding the roof. Position it with masking tape to hold it in place and check for correct alignment before applying the cement to the joint with a fine brush. Leave overnight to cure.

8 The axleguards and axleboxes come in several parts to allow for a degree of compensation in the axles. Fettle the parts carefully with needle files until the axleboxes slide freely (but not loosely) in the ‘W’ irons.

9 The bearings need to be secured to the axleboxes with glue and this in turn holds the front and rear sections of the ’boxes together. Fix one of the completed axleguards to the solebar, ensuring that it’s perpendicular to the floor.