Saturday 19 October 2019

Bethungra Loop - in "N" scale pt2

Having spent last weekend at the National "N Scale" convention in Canberra, my progress on Bethungra was slowed.  I had hoped to get all the track down for instance.  Still, the delay in the layout build was fully compensated with inspiration at the Convention.

The Convention may have a focus in N scale, but there were many non scale specific clinic topics, as well as some world class modelling to keep the delegates entertained.  Quite good retail support, with Peter Boorman's Workshops, Pallas Hobbies, and Badger Bits to name a few.  Clinics that I attended included  NSW stock yards, plug casting, weathering USA freight wagons, styrene buildings, lightweight module design and an interesting one from Greg Edwards on some of the background into the color images in the recent "NSW Railways in Colour" book.  The highlight though, for me, and most others was Ross Balderson's Newcastle 1899, which although not yet finished, actually had moving trains
Excellence in N scale - Ross Balderson's Newcastle 1899 has taken 7 years of construction to reach this point, but every building, vehicle (and ship) is a faithful representation of the original, many constructed based from period photographs

One of the side benefits of the convention, was I was able to purchase 2 x 1KG packets of N scale ballast (Bombo quarry), some will get used on Bethungra.  I even won a  brand new "Micro Trains" USA N scale boxcar as a lucky door prize - although I don't have a loco with the right coupling to immediately test on Bethungra.  Micro Trains (USA) was a major sponsor of the convention.

The next N scale convention is in Sydney in 2021.


Benchwork construction for the extension of Bethungra was a little challenging.  Unlike most exhibition layouts where module sections are bolted together, I needed a rise in elevation of the tracks on the extension.  The tracks would also cross the section boundary not on the flat - one track would have a falling gradient, the other a rising gradient. Anyway, best I illustrate the process with pictures.

Way back in 1985, the ACT Model Railway society built a module layout, that used a leg leveling system that used "T" nuts and bolts into the bottom of the legs.  I was the owner of 2 of these modules.  After 20 years of disuse, I thought they would make a contribution to Bethungra.  

I constructed an interface on top of the existing benchwork.  The T nuts and bolt were attached to the other side, leaving the bolt ends exposed.  These bolts don't extend to the edge of the benchwork, so they shouldn't snag during transportation of the sections.  And the spacing also allows the extension benchwork to rest on the existing benchwork, and then wiggled onto the end, and slid into position.  The wing nuts and washers tighten the join.  Note the profile variations for the trackbed at the ed
After adding the extension, here is the view from the current benchwork

Another angle.  The bolt is tightly forced into the T nut - it is unlikely to work loose in the few times the layout will be unbolted.  

The other pair of legs, and the new timber frame.  Using the existing benchwork as one end, makes assembly easy - although I have not added any leg folding mechanism.  The section will be laid on its side during transport.  The legs are lightly braced.  One other thing I would like to say, is that the plywood top was donated by the "Mens Shed", who gave me  more sheets that I needed for this project, although they will be handy when it comes to the Wagga layout.  To ease my guilt, I am supplying all the other timber and hardware to the Broadway Museum at no charge

I did not want to introduce an vertical "kink" in the join across the benchwork.  A metal ruler allowed me to see any variation.   The "down" track has not yet been attached

After cork and track had been installed, I added PCB slabs to the track on both sides of the join, secured with screws, before cutting.  The screws will enable some adjustments of the track  Up.down, left right to remove any variation.  And the PCB could also host checkrails, although testing has not needed them so far.  Note the screws came out of old VHS Cassette cases - I never throw away something that could be re-purposed 
Buried in one of my boxes, I had a pair of N scale through deck girders.  (Could be Peco).  A section of 0.040 thick styrene was added, and I had my deck bridge.  Tested for size.  Both the upper and lower track was not secured at this time.

On the workbench, some simple abutments were cut, again from 0.040 styrene sheet

After a bit of timber sculpting, the bridge is in.  The lower trackbed is still floating, as I wanted the upper track fixed first.  There is a 40mm clearance.

Cork added to the extension.  I cut my HO cork down the middle, which allows me to bend it to tight radius, AND allows me to align on the previously made pencil line radius - thus retaining the original centerline geometry 

Track down.  All flextrack.  It would be easier to use set radius curves for this, as the flextrack tends to kink when connecting them on curves.  However, with careful positioning of the joins, this can be minimized.  My test train is also pictured.  The F7 (or F9) is missing its shell, but runs OK.  The coil wagons were from my scrapbox, but good for this purpose.  I have been running the test train up and down the spiral, often at speed, and derailments were few, track fixed, and tested some more.   
During the convention, I spoke to a few modellers about my excursion into N scale.  Much to my amazement, an article on the original Bethungra Layout in the Broadway Museum had been published in an "N scale Modelling in Australia" magazine a few years ago.  A link to that issue is below.

Until next time.  Happy modelling

Saturday 5 October 2019

Bethungra Loop - in "N" scale

The Broadway museum layout

The Bethungra Loop, is a railway deviation, built in the 1940s, to ease the gradient up Bethungra Hill, and eliminate the need for banking engines.  The loop is located within Junee Shire.  The Broadway Museum in Junee contains historical items associated with the town, and shire, so it was not unexpected, that Junee, being a railway town, would have a number of railway exhibits.  One of them was a layout depicting the Bethungra loop. 

A NSWGR staged publicity photo of 3 trains on the loop.

Map of the loop, showing the rail deviation.  From a tourist viewpoint, there is little information about the railway.  All 3 elevations are visible from the Olympic Way road, but that is it.  Having seen the informative displays on the side of the Trans Canada Highway, of the famous spiral tunnels, the Bethungra loop is an opportunity lost

Many years ago, the guys from the Canberra-Monaro N scale group advised me of this layout.   They challenged me to rebuild it.

The layout was an attempt to portray the Bethungra Loop in N scale.  The layout was permanently installed in a room within the Museum.  The trackplan was not a bad representation of the loop, and the scenery could be described as sweeping.  Unfortunately, the builder of the layout had passed away before completion, and coupled with very poor benchwork and tracklaying, the layout was non operational.  The scenery was also incomplete.

Some pictures showing the original Bethungra Loop layout located in the Junee Broadway Museum.  Whilst incomplete, the possibilities of a great display were there.  The backdrops for instance were excellent.  Whilst the trees, and the track were saved when the layout was demolished, I am not sure what happened to the backscenes, as I could reuse them on my rebuild of the replacement layout.

There was another problem.  The room it was located in needed a lot of work – there was a water leak, plaster was cracking, and falling off, the floor boards were loose.  

Anyway, to cut a long story short, the museum eventually decided that the layout could not be saved, whilst the room was repaired.  The layout  was dismantled.  Some of the track was recovered, along with the trees, but most ended up as landfill.    Once the room was ready, a number of small display cases, displaying railway items, were installed.  A space was left for a small replacement layout, again of Bethungra Loop, but the replacement layout also proved unsatisfactory.
My standing offer to assist was accepted.
The replacement layout was moved to my garage, and is now taking up residence in my future train space

The replacement layout on a table

As there was no scenery, the inspection was straight forward.  In short, the gradients were too steep, some of the curves too tight,  the loop didn’t look right, electrics poor, and the trackwork marginal, with kinks, and some fishplates not seated correctly.

I discussed my plans with Bob from the Broadway Museum, and he confirmed the problems, and accepted that an extension was needed to better depict the loop.  Bob also said that they should be able to rework the display cabinets within the Museum to accommodate the slightly increased size of layout.  Bob also handed me some of the N scale track that had been on the original layout – track pins still attached.

Some of the track from the original layout. It was originally laid on balsa, and when pulled up, took the balsa with the trackpins

After depinning, and straightening, it looked much better

Reusing track.
Track that had been used before, is not something that is desirable for an exhibition layout, and certainly not generally suitable for a layout in a museum context.  But I did not have a budget from the museum to purchase new track, and I certainly did not have enough N scale track in my own accumulations.
After removing all the track pins from the flex track, I examined each section closely . Things to look for
1)      Kinks – vertical and horizontal
2)      Sleepers that had been pulled off the bottom of the rail
3)      Corrosion of the rail
4)      Sleepers that had become brittle, or were distorted
5)      Brand of track.
In many cases it was possible to snip off the offending pieces of plastic sleeper base, and slide the remaining sleepers  to cover the gap.  Serious kinks and corrosion of the rail were cut out and discarded, leaving 2 shorter lengths of flex track.  I also discovered 2 different types of Peco N scale, and a number of lengths of Atlas in use.   Ideally, best not to mix-n-match track types.

Stage 1. Gradient
The first step was to fix the gradient problem.  The trackbed, and supports had been nailgunned to the plywood base, which was not ideal.  Each trackbed section had been  buttjoined to the next on top of the vertical supports – introducing vertical kinks in the track.  This is not something that I wanted to repeat.   It wasn’t all bad.  The  geometry of the spiral was OK (the curves were a bit tight, but I was assured the train got around the spiral’s curves OK), and the “down track” grade was a consistent 3%, so I was able to retain some of the original layout

Track removed

After the supports were removed, the trackbed was kept for re-use

The track on all except the “down track” was pulled up, followed by the plywood roadbed. The uprights were extracted with a hammer. The uprights cannot be reused as they were full of nail gun nails
Additional plywood pieces were cut for a longer ramp for the “up track”.  These and the original plywood sections were joined together to form a single piece of roadbed.
Fitting new supports enabled a rising grade of 2 to 2.6% for the “up track”, allowing a 4cm vertical height gain for the spiral.  This doesn’t allow me to have the prototype’s deep cutting between the 2 tunnels, but compromises have to be made.

I cut a series of uprights with the drop saw. The number represents the height in cm 

Stage 2. Cork
3mm thick cork was glued to the new trackbed pieces, and all the cork was then sanded smooth.

Not the best picture, but it shows how I joined the sections of roadbed together - using scrap plywood.  I also used laid the cork double width, as this gives me more flexibility when it comes to relaying the track  

Stage 3.  Track restored to the spiral
When I pulled up the track from the spiral, I had hoped that the pieces could be reinstalled on the updated roadbed. This proved to be problematic, as many of the flex track joins were on sharp curves, and I could not get rid of the inevitable kink at the join.  So new sections of flex track were cut and positioned to avoid joins on sharp curves.    And before one asks, I am aware of the technique of soldering rails together using rail joiners before bending.  It is a silly thing to do if you cannot climate control your layout room, as expansion of rail in the heat, and contraction in the cold requires gaps at the rail joiners. A lesson learnt from experience

One of my essential tools for track laying is a mirror.  A mirror allows a rail head view, and can pick up kink problems quickly.  

Stage 4. Electrical considerations.
 The layout will operate as an oval, with only one train running in one direction.  Fairly simple electrics, but do not rely on rail joiners for carrying the current.  Every section of rail should have its own connection to the power bus.  I find working under layouts anything but pleasant, so I soldered jumper wires to the ends of all flex track pieces.  Yes, it may not be visually the best, but  once the track is painted, and ballasted, the brown multistrand wire will almost disappear.  To carry the power to the extension, a plug and socket is planned

Stage 5. The bridge benchwork and extension
On the prototype, the “up track”, after negotiating the spiral, is on the "down" side.  To get it to the correct side, it crosses over the” down track” on a deck plate girder bridge.   (see the aerial view and map at the start of this blogpost)  This aspect was missing from the layout I received, but in my opinion, had to be installed.  Re-installation also forces the extension of the layout onto new benchwork.   Unfortunately, I did not have enough real estate on the original benchwork to maintain the 3% falling grade of the “down track”, and another compromise, was to flatten, and then dip the “down track” under the “up track”.  A further compromise is that the below track plate bridge will need to be changed to a through plate girder.   Once the tracks cross, the “up track” will descend downwards, whist the “down track” will go back up, both tracks reaching the same level on the new benchwork.

New trackbed for the crossover bridge in place, but not yet secured

My hope is that the scenery will mask these grade changes, but this is something for the future. 
At the time of writing, the roadbed of the down track is not yet secured to risers.

Stage 6. The new benchwork track plan
As previously mentioned, both the up and the down tracks will resume their side-by side posture on the new benchwork.  At that spot, my hope is that the Olympic Way level crossing can be modelled.  I think it is important that people visiting the museum  can place themselves in the scene, as many would have crossed that level crossing on their trip to Junee.  After the level crossing, a balloon loop is planned.  The balloon loop will be left as raw benchwork, and not sceniced, as it is not part of the Bethungra Loop scene.
I settled on 27cm radius, as this was almost the same as the peco set track #2 radius pieces I had, approximated the now sharpest curve on the spiral. Fortunately, it was also about the maximum that I could fit on my extension benchwork

I was able to reuse the balsa from the original track as a compass for drawing curves.  Here is a 27cm radius
Just a mockup of track on the balloon loop.  I don't have a lot of N scale models, just a few  to test curves, grades and clearances.  The size of this board is 1200x600mm.

Next time.  Connecting the new benchwork to the old, track testing, track painting, and scenery starts

Whilst many would consider working on an N scale layout, not of Wagga, is a delaying exercise, I am using it as a welcome distraction. Not only am I getting back into actually building something, I am also trying out some ideas that may or may not  get used during the benchwork phase of the Wagga layout.  And as I am scheduled to attend the Canberra “N Scale” convention this October (10th-13th),  the timing is probably just right.