Rewanui - a 1940 West Coast NZ layout in 1:64

[SandiaPaul]

Great work...I'm about to embark on a split frame loco...curious what is your "commercial solution" you mentioned?

[Lawrence@NZFinescale]

Great work...I'm about to embark on a split frame loco...curious what is your "commercial solution" you mentioned?

Hi Paul

North Yard (northyard.co.nz), here in NZ, offer a 3mm split axle that comes in male/female halves with a moulded acetal bush to electrically isolate.  The whole assembly is push fit.  It's not too bad.  The male half is knurled to take a press fit gear which I find annoying as I like to use the axle for alignment in fixtures and the knurling interferes with that.  You are restricted as to overall length although there are some options, but it is easy enough to get one that is too long and to shorten the male half.  There's also a version that has reduced 2mm ends for smaller locos. They also supply axle material in 300mm length and if you can turn your own sufficiently accurately then the bushes might provide an easy way to do your own.

For kit production it is ideal as it gives an available, relatively simple solution with local market acceptance. For myself I'm a bit ambivalent as the knurling and incorrect length (for me) reduces some of the advantage.  They are also expensive for what they are.

For non-driven axles an acetal muff is often easier to do.  Obviously this gives a relatively fat axle between frames, but on a tank loco like the Wa you cannot tell.  As I have 3mm bore gears the driven axle is more problematic and the NY solution largely solves it.  To be fair if I were using NY wheels, axles and gearboxes then the whole system would be easier.

Note that the North Yard website is hopeless, and while it nominally offers an online shop there are few products actually listed so it's moot. Roger does respond to email though.  They no longer offer a catalogue, but the following is cut and pasted from a very old one I have on file.  Part numbers are still current I believe:

SPLIT AXLE PARTS stainless steel
North Yard split axles consist of male and
female axle halves press - fitted together with
an acetal insulating bush. The bush has a head
0.5mm thick; the length of axles that can be
produced is:
(male half length + female half length + 0.5mm).
While complete split axles can be supplied, it is
not advisable to press - fit metal wheels on to
these, as the force required will usually crush
the head of the plastic bush. Slide - fit wheels
with a 3.00mm reamed bore can be used and
secured in place with LOCTITE 601 or similar.
To press - fit wheels, the following procedure
should be used:
1. The correct bore size is 2.98mm.
2. Fit wheels and/or bearings and gear to each
axle half.
3. Push plastic bush into female axle half.
4. Press axle halves together. Check the
tightness of the joint, but do not disturb
unnecessarily. If the joint is not tight enough,
carefully twist apart, then apply a small amount
of Loctite inside the female end. Press the axle
together again and leave to set overnight. Be
careful to keep Loctite away from axle bearings
or you will end up with a non-rotating axle!
547 Axle half female Ø3 x 7.5
548 Axle half female Ø3 x 10
2857 Axle half female Ø3 x 13
2057 Axle half fem Ø3x8.5/Ø2x2.77
553 Axle half male Ø3x12 knurled
554 Axle half male Ø3x15.5 knurled
2858 Axle half male Ø3x17.5 knurled
2058 Axle half male Ø3x11/Ø2x2.77
529 Bush Ø2.5 x Ø1.6 x 5 acetal

[Lawrence@NZFinescale]

It's been quiet, so yet another digression..

I post these cowcatchers as they reflect the current limit of what is possible with the materials and methods available to me.  These are 1:64 and the rods are nominally 0.5mm diameter.

The eagle-eyed will note that I have had to repair some of the rods, hence the comment that it is at the limit.  Finer and/or longer rods won't print or cast reliably at present. These were printed in a castable resin by me and cast into silicon bronze by my local casting house.  Print orientation was arranged so that the rods were close to vertical to get a good print.  My feeds were perhaps a bit small and in some cases the metal has fed down each end of the rod but not welded together at the interface.  A touch of solder fixes that, but more generous feeds might have improved matters.

These are a one off pair for a project, although the digital pattern was not from scratch, being modified from a similar cowcatcher on hand.

[Bill Gill]

Lawrence, That's impressive.
Did the resin masters need much cleaning up from the print supports? If so that must have been a challenge with the rods being only 0.5mm

[finescalerr]

Maybe not perfect ... but close. I can't imagine seeing work of that quality ten years ago. -- Russ

[Lawrence@NZFinescale]

Lawrence, That's impressive.
Did the resin masters need much cleaning up from the print supports? If so that must have been a challenge with the rods being only 0.5mm

Thanks, I was impressed too - after all it is one thing to draw a part, but another for the technology to reproduce it. 

The printing arrangement is attached. Everything in grey is cast, the magenta bits are supports removed after printing. To answer your question, very little support clean up other than 2s flicking off the few supports which were not to the final part anyway (but see my final comment).

I have an approach which has been honed over time and typically:

• I print half sprues.  The faces in contact with the buildplate will later be stuck together (with wax) before being sent away (so the cowcatchers were cast as a pair on 1 sprue).  This approach tends to make printing faster (as the prints are short) and typically makes everything easier.
• I use supports (drawn in CAD) as feeds where possible. Generally this allows quite robust supports that mechanically support the model in printing, minimising purely print supports and the scars/cleanup they entail. My castings probably have more feeds than necessary as a result and these do need cleanup.  However castings need clean up anyway and I position feeds/supports where they'll either be easy to clean up or inconspicuous.  As seen here, there are a LOT of feeds, but they are all small and on flat back faces - so tidying them up is not hard at all.

The approach for printed 'waxes' can be very different to that used for moulded waxes from traditional patterns. With no mould step you are not constrained to a mouldable model.

I had to recreate the image for this post, and I now recall there were also a couple of small supports to the outside rods (as these are at a flatter angle). These did need careful removal with a flush cutter, but there were only 4 per catcher.

[Bernhard]

It's really impressive what's possible these days with 3D printing and precision casting. It opens up a whole new range of possibilities in model making, and I'm happy to take advantage of them.

Bernhard

[Ray Dunakin]

They look great!

[Lawrence@NZFinescale]

Not modelling in this installment, but the real thing.

We are fortunate locally that our relatively recent history is accorded some respect by government and volunteers who frequently make resources available for free.  The national film archive (ngataonga) is one such resource.  I recently stumbled upon the film in the attached link that features Rewanui at more or less the time I'm modelling it - A great treasure.

The film is amateur in B&W and (surprisingly) colour.  It is not clear over what time span it was taken, but some B&W scenes can be dated with some assurance to 1939/40 and colour scenes of the Rewanui incline feature a car that was probably gone from the region by 1947, so 1940-45 is my guess for the whole film (Not 1930 as the site states).  It jumps around in location a fair bit between Rewanui, the mines above that justified the railway and Rapahoe which was a sea level loading site for coal sourced from seams in a valley adjacent to Rewanui.

The film is an odd mix of things and starts very slowly and without sound, so you need to stick with it a little.  Over 330 people are listed as working in coal extraction at the mine in 1940.  The whole site is now a ghost town overtaken by native forest.
Scenes of specific interest to the model:
2:00-2:27.  Arrival of the morning miner's train to Rewanui station.  This whole scene features in the model including the train.
12:00  Rewanui bins on the backshunt.  In my model this area is represented by a fiddle yard.
12:08-12:50 the station and station masters house.  Absolute gold to have this elevation in colour at the appropriate period.
13:48 Hoppers being loaded at Rapahoe.  The location is a few miles off, but the rolling stock is spot on for me.
15:00-16:45 Ascending the incline.  Off scene for my model, but the trains are spot on. Shows the geography of the spot well.

https://www.ngataonga.org.nz/search-use-collection/search/F11644/

The attached pics show the area today.  The ironwork over the creek is what is left of the roperoad trestle featured in the film.

[1-32]

Hi Lawrence.
r
Really a great clip it puts your modelling into a proper perspective, love the miners finishing their shift and coming out of the shaft,so many stories there.
The location reminds me of that tragic mine accident about 10 years ago is it close?
cheers Kim

[finescalerr]

The color footage really puts things into perspective. Altogether a remarkable historic resource. -- Russ

[Ray Dunakin]

What a fantastic glimpse into the past!

[Krusty]

The location reminds me of that tragic mine accident about 10 years ago is it close?

About 20 km south-west.

[Bernhard]

An interesting piece of history with interesting detailed insights.

Bernhard

[Barney]

Lovely inspiration  photos
Barney