Thursday 18 October 2018

Kyeamba Creek Bridge - 3

Some things just cannot be rushed.  But, distractions aside, I am slowly moving forward  with the Kyeamba creek bridge build. 

In my opinion, the set of drawings done by Ironbark Models are the best ever done for an Australian kit, before, or since. These drawings are printed on glossy foolscap paper, and are remarkable, as the kit was limited to only 250 kits (my serial number is #11). Ironbark models disappeared from the scene shortly after their bridge extension kit hit the market.  I would be interested to know what happened to Ironbark, and how many of their kits were built, or still remain in cupboards, to be rediscovered.  

Building up the concrete “plinth” that supports the ends of the Kyeamba creek bridge timber spans was done with layers of 3mm MDF.  After sanding, this was glued to the abutments, and then painted with Floquil concrete.  A layer of 3mm basswood was then glued to the top of the subroadbed pine.   The wooden timbers were then glued to the top of the plinth, and the top of the abutment.
This subroadbed pine was cut to accommodate the existing timber abutment for the unnamed creek. 

The track embankment between the two bridges. I have already added a section of basswood to bring the height of the embankment up a bit - so the later cork layer will be at the correct (I hope) height
After some adjustments,  the base was ready for the Kyeamba bridge deck.

As my recovered bridge deck was only 4 spans, an extra span at each end was added.  I did have some additional stained timber in the Ironbark models kit box, however, this would only give me one span.  For the extras, I used 12” square  North-eastern stripwood.  However, this led to another problem – matching the stain.  For the life of me, I cannot recall what stain I used almost 30 years ago.  The Ironbark kit instructions mentioned a combination of Floquil “driftwood” and “walnut”, not that I had those at the time, or now.  So I made up a concoction myself from thinned down floquil paints, but it didn’t really match.  As my bridge will be viewed from one side only, I used my older stained  timbers on the viewing side, and the newer mis-stained timber on the other side.
The two bridge decks, after adding the extra spans

Some trimming of the bridge timbers to fit the gap between abutments, and time to start on the detailing
Due to a glitch with my measuring, the Kyeamba creek bridge ended up around 5mm too long to fit between the abutments. I would like to blame the thickness of the MDF, but the reality is that I goofed.  Anyway, both end spans had to be shorted by around 2.5mm - which is about 8 scale inches.  Hopefully it won't affect the appearance too much.  As a sideline, the official railway survey of the line states that the end spans of the Kyeamba trestle bridge, are 14 feet, and not 24 - but my visit, and photos show that this is incorrect.

The kit supplied Grandt line 1” Nut Bolt Washer (NBW) castings. These castings were painted rust, and holes drilled in the bridge deck – top and bottom.  Whilst fiddly, it actually doesn’t take a huge amount of time.  Good lighting, steady hand, comfy chair, and good music to listen to is suggested. My method is to fit a 0.6mm drill bit into an Archimedes pin vice drill, and a few seconds later, the hole is made.   After making half a dozen holes, transfer some PVA glue on the point of an ordinary pin to the hole.  Hint. I use the point of the pin to make the hole entrance slightly larger, and this also leaves a ring of glue around the hole entrance.   I use tweezers to transfer the casting.  Push the casting home, and the glue dries. Repeat the process until all NBW are installed

Bottom of the span.  Note the rebates in the corbels for the piers

Top of the span, also showing the Grandt Line NBW castings. The original plastic colour is black.

Sleepers are glued into the spaces between the NBW castings

The sleeper spacing is every 5mm - so getting the NBW castings drilled into the timber at the right spacing is fairly important.  Even so, there is still a lot of variation in my done by hand drilling.

New timber piers were made.  Again, I did not have enough stained timber to make all the new piers, and it was not possible to disassemble the exiting piers, as they were already cut for the now incorrect cross bracing.  
I raided my supply of timber, and found some dowels (OK meat skewers) of almost the correct scale 12”  diameter .  These were distressed with the saw blade, and then stained using a different method, which worked really well,  far better than my original staining method.  I may have to re-stain my original bridge  timbers to match.

The deck was again fitted between the abutments, and measurements taken for the 2 main piers that will attach to the timber base.  Shaping and fitting the piers into the jig was the easy part – cutting out the slots for the cross bracing was not.  Fortunately, the Kyeamba bridge only has cross bracing on 2 piers.
The central timber piers are 61mm high.  I have started to cut the rebate into the pier for the top chord.  The angle brace rebate is still to be cut.  Once one side is done, remove the assembly, and rebate the other side.  This is not easy, and I understand why it is easier to simply glue wood together to get the shape.  The weathering of the dowel has exceeded my expectations, and looks old and weather beaten - after all, the piles were installed for almost 100 years when I photographed the bridge, and have survived floods, and insect attacks.  

After completion of the pier, which included fitting yet more NBW castings to each joint, the pier was installed onto the bridge deck, returned to the bridge abutment base, and checked.  All OK, the pier was glued. 
One pier down, 4 more to go.  The peco track on the embankment has been put on some cork to check the transition from plastic sleepers to wood.  My original idea was to use code 100 rail for the entire layout, but I may substitute code 70 on the bridge area, and hand-lay the small area of the embankment with wooden sleepers.

There is much repetition now for the next lot of piers.  Then I have the unnamed creek trestle to finish, followed by the landscaping.  I keep telling myself this is a hobby.

Stay sane, build a model.