Project 24 - Battledown Flyover #8 (end of phase 1)

Considering phases of this project then this is the end of phase 1 in so far as all the 3D printing is complete. Next phase is the brick pillars, which will employ a different modelling medium. The final phase will be integrating the bridge into a landscape.

The last 3D prints to make and apply were the three top spanning girders. I am glad it is over because the manufacturing process is complex, messy and time consuming but frankly, there is no better DIY way of making a model with such high level of detail comprising thousands of rivets!

Track ballast has also been applied. This is sieved pumice grit with a sprinkling of cork granules for colour variation. Ballast is fixed in the traditional way of laying it dry and then flood with a 50:50 mix of PVA glue and water with a drop of washing up liquid to ease surface tension so that it flows easily through the ballast. When dry a black wash was applied to the track bed between the rails.

The bridge looks the part when viewed from the sides (normal viewpoint) but looking end on there is some bowing of the sides. I found it difficult to keep the sides flat as the cured resin took on a life of its own. As I have mentioned before the water washable resin used is not really tough enough to hold the shape of a model this size where thin sections are present.

By the way, the loco chimney does clear the spanning girders with about 5 mm gap.

To Part 9.

To Part 1.

Project 24 - Battledown Flyover #7 (track progress)

The track needed lifting by 1 mm on the bridge deck to mirror the level of the prototype. The obvious method was to use cork sheet as this may also absorb the sound from 'toy' trains as they pass over the bridge. 1mm thick cork was duly bought off Ebay but, what arrived was 4 mm thick! 

Evidently the vendor had no stock of 1mm (despite their listing showing stock available) and thought 4 mm would do! Well, I got a refund and searched for another supplier and I also wondered if I had anything that could substitute for it.

Right in front of my eyes on my desk was a spare sheet of 1.5 mm thick corrugated cardboard. Since this had air pockets then it too might be suitable as a sound absorber. In fact, a test with and without cork or corrugated board had no effect on sound absorption (probably too thin). Anyway, the corrugated cardboard was cut to size and glued in place using Copydex latex glue.

On top of the cardboard a paper track template was glued down to guide adjustment of the double sleeper sections of the track, which was glued on top using Copydex. Copydex with a little heat allows easy removal of track for reuse in the future.

The masking tape shown in the above photo was to preserve the raw plastic surface for later gluing in place the bridge sides.

My method of painting the track was to spray a mix of burnt umber and black acrylic paint (colours that I had to hand) then wipe off the overspray from the rail top.

When dry the cosmetic fishplates were glued each side of the rail at the joins

A mix of brown, yellow and red to mimic rust was hand painted along the side of the rails and over the chairs. The fishplates being picked out in black.

To Part 8.

To Part 1.

Project 24 - Battledown Flyover #6 (track prep)

In the early 1960s the track style at Battledown Flyover was quite different to that of today. Both the Salisbury and Southampton lines used wooden sleepers but their chair style differed. (incidentally no third rail). The Southampton down line was fitted with BR1 chairs and Spikes. I guess the up line was too although I have not seen photo evidence for it. The Salisbury line was fitted with BR3 chairs comprising a lip to hold the outer edge of the running rail, with a single baseplate screw to secure the outer side of the baseplate to the sleeper.  The inside of the rail and baseplate were secured with two spikes. Track was made from 60 foot flat bottom rail joined by four bolt fishplates and there were 24 sleepers per section.

Looking around at what stock I have there is a bit of Peco code 100, that is already allocated to something else but could be reclaimed for this project. There is more Graham Farish Formoway code 100 available, though not enough to build a layout so, I'll use this and buy more from the after market if needed.

When I rebuilt Misterton in code 75 bullhead I 3D printed the sleepers and chairs using my FDM printer for greater accuracy of chair style than R.T.R. track offered at the time. I am doing the same again, this time using my Resin printer to make flat-bottom rail sleepers and chairs. For the rail I'll strip it from my GF track.

I started with the BR1 design and lost count of the number of trials to get it to fit the rail smoothly. I measured the rail foot to be 1.9 mm wide. The 'trough' for the foot was eventually set at 2.08 mm. I think the failures were due to me not leaving sufficient clearance (by the way, the Peco rail foot is 2.3mm wide so, my chairs will not fit that brand).

I also designed and printed cosmetic four bolt fishplates.

The photos do not give justice to the fine details. With a magnifying glass the bolts and wood grain are clearly seen!

To Part 7.

To Part 1.

Read about the SLA (stereolithography) resin 3D printer I use here.