Wednesday 16 January 2019

Tumbarumba Turntable - pt 1

The Tumbarumba Turntable.

Turning locomotives at the end of the Tumbarumba branchline was performed with a 60' turntable, large enough to take standard goods 2-8-0, C30T 4-6-0, and any C32 4-6-0 that happened to venture that way on tour trains.  It is also turned 48 class diesel electrics, although I just do not know if the CPH railmotors were turned for their favoured #1 end leading.

The turntable is a standard NSWGR 60' steel design, installed around 1921.  Manual operation.  Only one entry track, although the extension through the turntable was the home of the engine shed (actually a carriage shed), hopefully removed before 1970, as I have no space for it.

Tumbarumba Turntable, as I found it in December 1980. Yes, I know I have used this image before

Similar turntable at Cootamundra, photographed last year.  This supplied me with the details that my earlier picture did not

The model.

On the layout, the Tumbarumba turntable is going to be located right on the edge of the benchwork, close to the operator aisle. 
A ready to install model of the NSWGR  60 foot turntable is a made-to-order model from Anton’s Trains, and whilst I had already obtained one for Wagga, I had neglected to buy the turntable for Tumbarumba.   Antons turntable is  electrically driven, has multiple track aligning (which could suit a small roundhouse) and a full size pit.    If I was using an Antons turntable for Tumbarumba, the full size pit would have to be modified, as I am sure Tumbarumba only had abutments.

However, I like to challenge my skills, so, instead of buying, I thought I would make a turntable.  If I could emulate the prototype, and have a manual operation, then that would ease construction.

Construction starts

Over the years of not having a layout, I have been thinking about a turntable design, using a PC hard disk drive bearing for the central pivot.  And more recently, I came up with an idea of using rare-earth magnets for the alignment of the bridge with the end abutments.  So after buying a set of button magnets off the internet, I was in a position to start

Thank you should also go to AMRM, who had a plan of the steel 60’ table drawn by Alan Templeman (AMRM Issue 133 way back in August 1985).  The model railway magazine is a brilliant resource, and their on-line search function saves a lot of time.

an old harddrive bearing, after the case and metal disk platters have been removed. Note the pair of machine screws - the top of the bearing comes already drilled, and tapped

Hole saw cut hole into a piece of timber to accommodate the bearing depth


Bearing secured on timber with 3 screws


Brass turntable sides cut from scrap brass sheet, and assembled on a base of brass

View from above. Note the wooden block used to space the sides, and also maintain the joints being square

-          Brass turntable assembled on board for testing.

After securing the base to the bearing with the two screws the height at each end of the turntable bridge was tested with a makeshift pile of boards. It is vitally important that these align.  The harddrive bearing has ZERO slop.  I have added one of the two angled bases so you can tell what end is what 


extra brass added for the walkway, and an upper support brace has been added
-         Bulking up turntable pit 
Balsa framing

 Glue an MDF top with clamps. The top of the bearing pops through a hole in the MDF, and sits around 2mm higher.  Check to ensure the bearing still freely rotates.  The glue is intended to be permanent, so no more bearing adjustments are possible after this step
 Track assembly
Two 21cm (60 scale feet) of rail were cut, and assembled on PCB sleepers. Don't forget the electrical gap

-          Ring and Abutments.
 There are probably a lot of ways to construct these, but I chose a method that works for me with the tools, and material I had

I drew a circle using the end of the turntable as a guide, and then proceeded to glue on scrap blocks of balsa to act as the base for the future ring rail.  The balsa thickness was chosen so as to allow an assembled ring rail to fit under each end of the turntable bridge with not much spare space.
The gaps between the balsa blocks were filled with Aldi brand filler, and once dry, quickly sanded.  Painted concrete, with a ring rail above, any imperfections will look natural.  The bearing is only just visible, but looks OK.  The pit will also need to be filled with a slope matching the bottom of the turntable bridge.  Note the track now added to the top of the turntable - this is not yet secured.  The abutment timberwork is also missing, but I do have the track baseboard extensions down.

 Well, I think the turntable is about half done.  The magnetic alignment/locking is still to be fitted, and when I am happy with that, I will finish the track laying.  The pair of abutments will need to be completed,  the turntable will need finishing with a top cover, handrails, and some additional details.  Then painted.  The pit will also need its ring, and I have to arrange the electrical wiring to each turntable rail.  Of course, the pit has to be filled, and detailed too.  

Stay out of the sun.  Build a model, or read a model railway magazine.   Until next time.

Detail from Cootamundra  turntable.  A sign like this would add some spice to the fascia on the layout

Friday 4 January 2019

Kyeamba Creek Bridge – track installation

Adding the track.

Welcome to 2019.  To celebrate, it was time to get the track down across the Kyeamba Creek Bridges.

42102 heads south approaching the Wagga station platforms, with a train of VR cement hoppers in around 1981.  The double slip connection to the main line had recently been disconnected.  Supplied picture - photographer unknown, used with thanks ( If it is your picture, please contact me)

After adding more foam scenery, I repositioned the bridges, and made some minor adjustments to get them sitting right.  This was not helped by the 6 span trestle getting a minor longitudinal twist.  I removed the rails from the plastic sleepers on 2 sections of flextrack, and painted the rail sides with  roof brown.  After drying, the sleeper base was added, leaving gaps where the bridges were.
I had 2 options for attaching the rail to the bridge.  The first was spiking, the second was glueing.  Call me lazy, but glueing was selected.  The main running rails were glued to the paper sleeper or tie plates with 6 minute 2 part epoxy.  This glue was smeared to the underside of each rail, and then positioned on the bridge.  Note that it important to get the rail straight, and to have the rails at the correct gauge.  Please note the picture which shows peco plastic sleepers being used to hold the rail gauge.  Yes, the head of the rail can be clicked into the plastic sleepers gap, and holds on nicely.  Had I been using a finer rail, then I am not sure that this method would work.  Code 100 is very forgiving, and my experience with exhibition layouts, says that reliability starts with good trackwork

Rail being added to the unnamed creek bridge.  Note the Peco track sleeper base, being used upside down, to hold the correct track gauge,  To ease installation, the rail was added to each bridge separately

Once the glue had set, the plastic sleeper base was secured to the diorama with pins.  The railhead was then cleaned of any surplus paint using a masonite pad.  I try and avoid using abrasive track cleaners, like peco or bright-boy,  if other less destructive methods work.

Check rails also painted prior to installation.  I am not sure if using tacky glue will hold these in position, but because they are not installed on the tie plates, their rail head is lower, allowing future cleaning of the running rails to not also clean the check rails.   I didn’t add check rails to the unnamed creek bridge, as I had no photographic evidence that they were on the prototype.

Ballasting followed.  Secured with white-glue/water/alcohol mixture, and allowed to dry.  Securing track pins then removed.

Checkrails added to the Kyeamba Creek trestle. The creek "water" has been covered with a layer of gloss medium, and this gives good reflections.  I am not sure if I will do a 2 part epoxy clear water mix to give more depth.

No checkrails for the unnamed creek trestle.

Well, this finishes the bridge diorama until installation on the layout.  The idea of fitting trees, and bushes, whilst the diorama is stored on edge is a recipe for a mess.  I am sure there will be additional tweaks to cover gaps, and touch-ups to raw “plaster” showing.   Thank you all my readers, and followers for your comments, and encouragement, on what has been a long project.
Time to start something new.  Until then, happy modelling.

A teaser to what a typical branchline train might look like on the layout.  The blue backdrop was previously painted 30 years ago for a now scrapped module, and propped behind the diorama.  The train is a Wombat Models C30T, a pair of SDS BCW, and a Trainorama PHG. 

An empty stock train heads over Kyeamba Creek towards Ladysmith

I will be hiding the distortion in the creek bank with a blackberry bush,

The best of this group of images.