Tuesday, August 25, 2009

How I assembled the station buildings

The station buildings on the Peckforton Railway are all based on kits from TM Models to maintain consistency at each station. The kits comprise key components cast in resin which need to be glued together. This posting outlines the construction of the station building at Beeston Market but the same methods were used to construct all the buildings with slight variations to suit the needs of each building. (See Progress Report 25 and scroll down the page for more info on the station buildings)

On opening the kit, the walls, roof and fittings were laid out for checking. The doors are moulded into this kit, with others, the doors are separate mouldings which need to be attached.

The first job is to tidy up the mouldings. Inevitably with the moulding process, some of the surfaces need a little filing down to help ensure a snug fit. As you can see, I tend to use my knees as a vice to avoid damaging the mouldings, and run a large flat file over the edges to be joined.

The walls were joined first. I prefer to join all four walls at the same time on a cutting mat with squared markings. This enables me to make adjustments while the glue is setting to ensure everything is level and square. I use 4 minute rapid-set epoxy as this gives me some fiddling time.

To hold the building together while the glue was setting, I used string or twine looped loosely around the model and then tightened by twisting lollypop (popsicle) sticks into the loop. A small loop of twine stopped the lolly sticks from unravelling.

While the glue was hardening, I tidied up the other mouldings such as the window frames, using fine needle files:

Once the glue holding the walls was set sufficiently, I tidied up any inconsistencies with a file and then glued on the corner pieces. These were held in place with the twine loops used previously.

The next job was to fix one half of the roof in place. The upturned building was placed on to the roof and left for the epoxy to set. From experience, I've learned it is important to make sure the roof is carefully positioned along the ridge - otherwise the other half of the roof will not fit properly.

Next, the other half of the roof was fixed into place.

With some buildings, I fixed the other half of the roof in the same way as the first half, but for some reason this roof section needed to be twisted slightly to fit into place. Maybe the first half wasn't as squarely fitted as I thought. I therefore needed to use my tightened twine method - in fact the twine wasn't strong enough and so a sturdy piece of red tape was deployed instead.

Next, the barge boards were trimmed and glued to the eaves. Packing pieces made from lolly sticks which supported them while the glue set.

Next, the finials were filed down and added:

and the self-adhesive strip was added to the ridge and scribed to represent ridge tiles.

Rather than gluing the chimney stack directly to the roof as intended, I decided to position it on the ridge. After marking out the position a hole was cut using a razor saw and craft knife.

The chimney stack was then glued into position and held in place with an elastic band while the glue set.

Finally, before painting, the window frames were fitted. On some models I have painted the doors and frames before fitting but as the doors on this model were moulded into the walls I decided to fit the window frames and then paint them at the same time as the doors.

I could have left the walls their natural colour but decided to paint them with watered down magnolia exterior wall paint to which had been added a little yellow acrylic. The doors, window frames and corner pieces were picked out in Brunswick Green enamel.

The roof was firstly given a thinned wash of dark grey acrylic, which was then wiped off with a paper towel, leaving the paint in the crevices. Individual slates were then picked out in varying shades of grey.
The frame of the noticeboard was picked out in green enamel while the board itself was painted with black acrylic to which some talcum powder had been added for a matt finish.

The chimney stack was dry-brushed with brick-coloured acrylic with some individual bricks picked out in slightly different shades. The chimney pot was painted orangey red.

I then added posters and representations of enamel signs which I had printed out (see How I created signs and posters). The whole lot was given a couple of coats of varnish from an aerosol to protect the paint and posters from the elements and finally the glass was glued into the window frames:

When time and finances permit, I will add more station clutter and figures to the model and its surroundings. (eg see How I made some milk churns). I decided not to weather the models as probably, within a couple of years of being placed out in the garden, they will weather naturally.

I intend to store the buildings inside when not in use, but it is highly likely that during the summer months they will remain outside for most of the time. Time will tell how the posters fare but hopefully the coats of varnish will protect them for a while though I know from experience that slugs and snails seem to love eating paper and card!

Monday, August 24, 2009

How I made the swing bridge

NEW- A video showing the construction of the bridge

Despite there being no prototypical need for a swing bridge, I decided that the plank bridge across the entrance to the sheds would benefit from being detailed. A quick calculation showed that the ten foot length of the plank more or less coincided with the overall scale length of the swing bridge on the Southwold Railway. (See also p10 of the SR Trust Nov 2007 Newsletter).

Having read about using uPVC fascia trim for the construction of girder bridges on the G Scale Mad discussion forum, I went off to my local EuroCell store and purchased four 5m lengths of 25 x 23 cm angle trim and a bottle of superglue for less than £20.00.

Using a scale drawing of the first Southwold Railway swing bridge, I worked out the dimensions of the model in 16mm / foot scale.

Although the main members of the original bridge were either 15" or 6" wide, I decided to slightly over engineer my model to ensure it was robust enough. For the wider members, I trimmed the angle down to 20 x 20cm and 12.5 x 12.5cm for the narrow members. This meant that the 12.5cm off-cuts could be used as tie-bars.

A carpenters' marking gauge was used to score lines down the length of the angle trim.

A craft-knife was then used to cut through the rest of the trim. I found the knife had a tendency to wander if too much pressure was applied, particularly with the first two or three cuts.

The bottom member was marked up. The first two verticals either side of the middle are 8' (128mm in 16mm scale) from the centre, the remainder are 10' (160mm) apart. The final two members at each end are 2' 6" (40mm) apart.

The verticals were then cut to the following lengths:
  1. (Middle) 9' 9" (156mm in 16mm scale)
  2. 13' (208mm) with a slot cut at 9' 9" (see below)
  3. 9' 3" (148mm)
  4. 8' 6" (136mm)
  5. 7' 6" (120mm)
  6. 6' 3" (100mm)
  7. 4' 9" (76mm)
  8. 3' 3" (52mm)
  9. 2' 9" (44mm)
Using a tri-square, the verticals were superglued to the horizontal:

It is possible to buy an accelerator spray from Eurocell which is designed to set the superglue virtually instantaneously. However, I used clothes pegs to hold the pieces together while the glue set. I'd suggest using disposable latex gloves when using superglue. If you're anything like me you'll find it impossible to keep the glue off your fingers and having the painful job of separating them from whatever they've become attached to (including each other!).

For the central verticals, I glued two pieces of angle back-to-back to make a T-section. This was for symmetry. On the original, the majority of members were T-section or channel, but I decided to compromise for ease of construction.

For the longer uprights either side of the middle beam, slots were cut in one of the sides with a needle file, similar slots were cut in the upper horizontal beam to enable these to slot together:

Working outwards from the middle, I glued the uprights to the upper beam. I soon realised that I needed to anchors the lower horizontal to something substantial to ensure it was not pulled out of alignment. Fortunately, I had an 8 foot fence post to hand and screwed the lower horizontal to this. The two sides were thus completed:

Rather than modelling the ends as in the original, I simply angled the upper beam down to the lower beam and glued them together.

To compensate for the vagaries of my model making, the lengths of each diagonal was measured:

and cut:

and the angled ends trimmed by eye:

with a pair of scissors:

before being superglued in place:

I figured that the diagonals which are 'uphill' when moving away from the centre would be under compression and hence would need to be constructed from angle, whereas the diagonals which are 'downhill' from the centre would be under tension and hence would be from plate (ie the 12.5mm offcuts). This would greatly simplify the construction as the second diagonal could simple be threaded under the first diagonal.

The same approach to measuring:



and fixing:

was adopted for the second set of diagonals.

Once the glue had set, the sides were removed from the fence post and a representation of rivet detail was added using blobs of superglue gel. This proved to be a somewhat haphazard method as the consistency of the gel varies and hence the flow of glue is difficult to control. Consequently, some rivets are more regular than others:

Those with more time and patience would probably want to use a more reliable method.

Painting was completed via two 500ml aerosols of Halfords grey primer:

The pre-existing plank bridge was somewhat basic and needed a little modification to accommodate the new structure.

Firstly, the deck needed widening to the scale 12' 3" (18.4mm) of the original. This was achieved by screwing a few lengths of treated fencing battens to each side.

The bridge sides were then screwed to these. A couple of pieces of angle were glued across the uprights to link the sides together:

A square hole was cut into the base of a large paint-pot of roughly the right diameter (19' - ie 30.4mm in 16mm scale) for the central caisson. This was slotted over the existing centre post and the base buried into the ground.

Four legs, recycled from a plastic shelving unit were cut to fit beneath the ends of the swing bridge. Discs were cut out from a redundant piece of pine shelving to fit inside the legs.

The discs were screwed to the base of the bridge and with three screws the legs were attached to the discs.

Cross members made from spare pieces of uPVC strip were attached to the legs and then the caisson and struts were sprayed matt black.

The bridge was then tested for clearances:

I have made a few compromises which might upset the rivet-counters. The deck of the bridge should be an open lattice with longitudinal timbers beneath the rails. I would imagine that this method of construction would happily support the track and traffic, but given the location of my bridge I've gone for something more substantial. As indicated above, the diagonals ought to be 6" (8mm) wide whereas I have gone for 12.5mm (10") and the main members ought to be T-section. I've brought the upper and lower horizontal members together by completing the arc, rather than truncating them.

At present, the bridge still swings from one end rather than the middle (see also How did I bridge the gaps?) - maybe one day, I will devise a mechanism for more prototypical central swinging. However, I think the model captures the elegance of the original structure sufficiently well and certainly provides a focus for the line.