Here’s a quick post on the latest product update from NZF.
We have had cast groundthrows in the past from an excellent pattern by Peter Ross. Unfortunately our caster managed to ruin both pattern and rubber and these are no more.
So I’ve redone them with improvements. You now get 2x groundthrows per sprue (either two of the common type or one of these plus a gooseneck). The main parts are cast brass, while the gooseneck lever and cranks are etched.
Both levers work as the prototype does, but we do not recommend them as working throws as they are a bit fine for that. They are S scale and both of these will sit on a 20 cent piece with room to spare.
Price is $7.50 per sprue of 2 levers and a small fret of etched bits.
The first throws out of the mould
Rewanui is a station in a narrow valley. That makes it interesting visually, but any manual intervention in operation is difficult as well as unsightly. Automatic uncoupling is therefore very desirable. Doing it with DCC is the icing on the cake.
To whet your appetite I can announce that I have a working, DCC-compatible, NZR pattern coupler with an operating mechanism that is small enough to fit in an NZ120 loco. Details will drag out over a few posts though as I do some development.
Step 1
The first thing I pondered long and hard over was the lifting of the hook. There’s been a few variations on this over the years, but I think mine is original. The basic idea is to arrange a fine wire across the face of the buffer head. When this is moved it lifts the hook. The downside is that NZR couplers do not have lengths of extraneous steel flapping around in this area. On the other hand a 0.008″ guitar string is all but invisible at normal operating distances. In addition, since Rewanui stock is not turned, the operating mechanism can be placed away from the viewer. Even so it’s visually far less intrusive than RP25/110 wheels that almost everyone else uses. So this is what it looks like:
The concept in CAD
Its worth clicking the image for the full size version. The coupler on the right shows the wire arrangement, with the wire in blue. A small (0.3mm) hole is required in the buffer face. The centre image shows the arrangement when coupled and the leftmost image shows the wire rotated about the longitudinal axis lifting the hook.
My initial trials involved attaching a soft iron wire lever to the operating wire back under the wagon where such a thing could hide amongst the brake gear. Waving a magnet underneath the wagon caused the hook to lift in a very satisfying manner. A couple of mockups proved that this is a viable uncoupling method, and it is one I’ll be pursuing as DCC uncouplers in every wagon are hardly practical on many counts.
In summary, I think this idea has many virtues:
- It is pretty simple (cheap and quick)
- It is compatible with stock not fitted with the autocoupler
- It has a prototypical look
- It would be compatible with any other hook lifting idea that might be developed – so it’s forward compatible.
- Manual operation is unchanged
- The wire acts to centre the coupler – an important attribute for coupling up.
- As we’ll see later the 90 degrees of rotation required can be achieved with a simple actuator that can be DCC triggered.
In future posts I’ll explore the aesthetics and operation in more detail.
Thanks to Nigel Cliffe for ideas and inspiration on this project.
The last few posts have described my progress with rapid prototyping. This one closes the loop and sums the whole experience up. Not that it’s an end – rather a new beginning.
What’s new here is I’ve had the plastic RP output cast in ‘brass’ via lost wax. Nothing original here, except that I have to say Morris and Watson are doing some of the best stuff that I have seen from them at present. Brass is in inverted commas by the way as it’s actually some kind of bronze. The alloy they use seems to vary from time to time. The current lot is quite silvery and hard.
This first batch of RP has been a rather esoteric assortment of bits. Partly this reflects the projects on the workbench, mostly I’m just a kid at heart and moved by whim rather than any systematic approach. In any case here is the new NZFinescale BP508 bogie sideframe from inspiration through to finished part. Now I have the castings I’ll be producing some complementary etchings for a full bogie kit, but in the meantime:
The real thing at CRS Ferrymead
The motivation on this one is the 35′ birdcage car which had this pattern bogie for most, if not all, of its life.
So first up BP508 was obtained from NZR archives via John Agnew (Thank’s John – it’s been a long wait). The bogie was drawn up in CAD and then output to an stl file.
A render of the stl file
At this point we are still very much virtual. The file is emailed off to the RP merchant and back comes:
Ideas of substance - the virtual made real
Now we have a pretty nice pattern, and it’s a relatively simple matter to sprue the parts up for moulding and casting. Since the RP plastic is heat sensitive the sprue is styrene and a cold mould will be needed. The parts were committed to the tender care of the Post Office and after another short wait and lightening of the wallet (drum roll):
Sideframe in brass. The first of many.
So what do I think?
Well firstly, the casting photo doesn’t do the casting justice. It’s a beautiful thing and there is no way I could have bettered the result by any practical means available to me today.
Interestingly though, the least satisfactory step (in terms of quality loss) is the casting. The RP process has limited resolution (0.05 mm I believe), but this is quite sufficient to clearly print ‘ NZR’ on the axlebox, but unfortunately results in clear layering on the face of the axlebox cover. The casting isn’t quite good enough to pick up the layering, and the sharpness of the ‘NZR’ is reduced. I’m pretty sure a urethane casting would be better, and I’ll certainly try it. However, there are some things you want metal for (like wheel centres, fine parts and those with a mechanical function). But these sideframes could be urethane – they will be supported in an etched brass frame so strength is not really a major issue.
Look out for further goodies in this series!
By the way, all the images in these posts are clickable and open at higher resolution should you want to see details more closely.
Lawrence
Back in November I posted a virtual model of the pyle national generator.
Thanks to the magic of Mark G and his rapid prototyping machine, here’s the real world model in genuine translucent red plastic:
The plastic model direct from the RP machine
So what’s the verdict?
Well first up I should point out that this particular project is a pretty harsh test of the technology. Small objects with tight radii are a big ask for the available resolution. This is also a huge enlargement. At the scale of this image the whole loco is going to fill your dining table and then some, so bear that in mind when assessing the results. Remember this little piece is around 8mm in the long axis. (There’s a piece of blu-tack in there for photographic mounting purposes as well)
- It worked! All the detail in the virtual model is there in the print.
- Layering is very obvious in this image – but it certainly isn’t at the sort of magnifications we are normally going to view a 1:64 locomotive at.
- The detail and proportions are just right. These things certainly are visible and obvious under normal viewing conditions.
So I’m pretty rapt. Stay tuned for more on this subject. There are a bunch of other RP projects at this stage on the work bench. The next step is to get them into metal.
Only 40 minutes until the big day – so:
Seasons Greetings to all – Ho Ho Ho!
My borrowed copy of the latest NZ Railfan has an article from John Agnew on 35′ cars – and one promised in the near future on the 35′ birdcages specifically. As is often the case, all the information I ever needed willl arrive just when I no longer really want to know.
In the meantime the car progresses.
The spec at present is an interesting one. Whether the following ideas all come to fruition we’ll have to wait and see. The idea at present is:
Wheels. As with all my stuff this will be finescale wheeels on 16.5mm gauge track. The wheels are broadly similar to P4.
Bogies. These were type 508, and no decent model of these exists as far as I know. I’ve got some rapid prototype patterns in the works, and there will be some etchings to go with these. Basically they’ll be simlar to the familiar North Yard bogies in design though.
Underframe. I pottered around with styrene like I did the last time, but too many rivets in the solebars distorts the plastic. So this is going to be brass and more or less prototypical, as per the photo below.
End rails/gates and wiremesh will be the NZ Finescale products of course.
The doors are all etched, but the body will be a styrene scratchbuild – much of which I did a long time ago.
The roof may be a laser cut clever thing – this aspect is still being mucked about with.
magnetic jig to hold everything in place
Once I had a few underframe bits cut out I had the usual urge to put them all together to see how they looked. In the first case I set them up on a bit of steel plate that was lying around. They didn’t really stay put of course, and my eye lit on a chain of recycled magnets adhereing to the filing cabinet. These are the modern very strong type about 6mm in diameter and about as high. These held the parts in position for my mock up with great success. The photo shows the latest version of this idea. I’ve graduated to a larger plate and theres a paper copy of my 1:1 CAD drawing for the underframe laid over this. The parts are positioned over the drawing and held in place with the magnets. When I’m ready to solder everything up I’m not anticipating burnt fingers. I’ll just use the soldering iron on the parts more or less as they are depicted above.
By the way, suitable magnets are listed cheap on TradeMe.
Something tangible from the modelling bench …
The last few weeks have seen a flurry of modelling activity here at House of NZFinescale. With a bit of luck this blog will see the fruits of this in due course.
Today’s contribution starts with some history… Etched wire mesh was one of the earliest products NZF produced – ES006. In part this was a response to Peter Ross’ birdcage wire that he had etched sometime earlier, in part to see how fine we could go, but mainly to produce something for my own birdcage car project. The result, built a long time ago, is illustrated below. This is the working side – the ‘good’ side is tidier. Birdcages came in a variety of lengths and styles. As a result the mesh panels also differed, so the NZF product is a length of mesh that needs to be cut and fashioned into something appropriate to the project at hand. This is a bit painstaking to be sure, but at least with the 35′ car there is plenty of extra for test runs.
35' Birdcage car wire mesh
The car is an interesting project, made far easier by John Agnew who provided the NZR drawings together with photos of both Westland examples – A416 and A420. Easier, but not easy unfortunately. The 35′ saloon car drawing B.P. 1707 has a couple of partial sections and the comment ‘For general design of car refer to B.P.1451′. This latter is for a ’41′ Saloon car’, and is fully detailed. However, ‘general design’ is not very specific and there are a few details to nut out with reference to photos and basic geometry. Likewise the underframe drawing I have (B.P.1702), only shows the general layout – so again there is recourse to drawings of similar cars and photos. There’s also John’s article from NZMRJ October1985 which covers the genera, but is short on information on the species of interest. Which is something of the cause of delay in seeing the emergence of this project from the shops.
Another problem that quickly became obvious as I embarked on the original build is that the the structure and framing of the roof is open for admiration in the vestibule area of the car. My previous clerestory roof method, which was good in ouside appearance but quite unprototypical, would not suffice here. It was at this point that the wirework, a couple of styrene car sides and accumulated research material drifted into that area of the work clutter called the ‘too hard basket’.
Fast forward to 2011. Rewanui is moving on and I could do with at least another one or two passenger cars to convey miners and sightseers up the incline. So the birdcage car is on the bench once more. I have etched and assembed all of the doors, done the plates, lain awake at night pondering possible construction methods and begun investigating that clerestory roof.
Stay tuned – There’ a few more blog posts on this topic I feel.
The Omoto locomotive dump November 2011
Its always handy to keep model making in the right context, and how better to do so than wandering out into the world of the rail fan? The Mainline Steam excursion from Greymouth to Westport and return was something we hadn’t done before so it was off to the Coast for the weekend. As a trip it was most enjoyable and the Buller Gorge by rail is a great experience. A steam trip in ‘modern’ passenger cars is a bit of a waste of time though – it could have been anything up front, and the only way to get some smoke into the lungs was to cram on the miniscule deck of the crew van – total capacity 6 persons.
We noted from the train that a good sand bar had formed in the area of the Omoto locomotive dump and that the tide was out in the early morning. So the following day we went for a look. (For those not familiar with Omoto, try Googling ‘Omoto locomotive dump’). We dropped onto the ‘beach’ below the Omoto viaduct and wandered a short distance upstream. There was plenty to be seen but some of the published maps of the site are somewhat out of date – presumably because the river has been shuffling the pack. UB, UC and F locos were clearly evident from the riverbed though with an interesting melange of Q and L wagon remains.
As a research exercise we were at least a couple of decades too late, but there was a beauty to the whole thing as I hope the photos show:
An F loco with Q hopper garnish
Tasteful fern decoration of a Q headstock
Delightful LA wagon setting for some daisies
UC cab fretwork
One of the great things about the model railway hobby is that there are so many different things you can do within its broad boundaries. Readers of the blog will know that I’m stumbling erratically towards a layout based on Rewanui. Today’s digression relates to locomotives for the layout…
Screen grab from the stl file ready for prototyping
In contrast to the clean look of English locomotives, NZR locomotives from the early 1900s tended to festoon gubbins on the visible surfaces of the loco. This makes them visually interesting, but rather time-consuming from a modelling perspective. It also means that castings for all sorts of parts need to be found or, for the avid DIY exponent, made.
Until relatively recently this meant crafting a pattern from scratch as I did with my small Westinghouse pump pattern some years back. This part took over a week of intensive effort with numerous false starts and failures, and from memory there were something like 60 individual pieces in it. I’m still pretty pleased with the result, but it still represents a significant compromise over the real thing.
A casting from the handmade Westinghouse pump pattern
Jump ahead to 2011, and we have the intriguing possibilities of rapid prototyping. In short, make a 3D computer model of your part and ‘print’ it out. The principle is now well established and it is a viable way of mastering castings, but is it any better?
RP does suffer from a layering effect as an artifact of the process. With a good machine and competent operator this can be minimised, but it can still be a bit of an issue. However, the scope in the pattern design is greater, so you get more accurate detail. So there are some swings and roundabouts in the finished pattern.
There are some big pluses in the approach from the pattern making side though. These are:
- The ‘undo’ button. If you make a mistake you can easily go back a step. This is a major pro over lathe work!
- Copy and reflect. You only need to make one piece in one hand. If you want more bits and the other hand this is just a mouse click away.
- The pattern is safe on the hard drive. There is nothing worse than having the pattern destroyed by the caster with no option but to remake it. With RP it just needs reprinting from file.
- You still need to learn the appropriate skills and the pattern building still takes time, but overall the process is quicker and, if properly realised, better.
The pattern in the top photo is a Pyle National generator ready for RP (I hope!!). This took a couple of evenings work. It’s a little chunky, but the pattern is only 8mm in the long axis. Those bolt heads are only 0.3mmAF or thereabouts.
In a few weeks time I’ll report on the results.
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Well it’s been a long time between posts. The modelling room has been left untouched for 12 months and has been left more or less in its post quake state. There’s not a lot of point picking things up if the earth is going to move again and undo all the good work. However, I’m cautiously optimistic that this particular seismic event has more or less played out and real life can resume.
What’s new? Well I have a 10 year old son applying pressure to move ahead. I’ve visited the gurus in the UK, and I’m modelling on a daily basis. So hopefully the blog will fill with revelations as they unfold.
Things on the bench right now are too many to list. Things at the top of the heap are:
- The track
- The large rockface uphill of tunnel 2
- W192
- a 35′ birdcage car
- The small bridge uphill of tunnel 2
- A new fell van kit.
All that’s still to be photographed though. Some on the spot reaseach at Ferrymead on the weekend turned up W192 being lit up on the Saturday – so plenty of opportunity to climb all over it in good light. The opportunity for cab rides on the Monday was too good to resist.
On asking around the remnant of the length of fell track that used to live next to the station was located too. The track is where it always was, unfortunately some heathen has removed the more interesting bits and dumped them behind the carriage shed, where I took the photo below.
All thats left of the incline in the grass at Ferrymead
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The blog’s been a bit neglected of late. What with the Christmas rush, the big day itself, as well as some good weather to enjoy, cyberspace has not been high on the ‘to visit’ list. However there has been some activity at the modelling bench. Most notable are a number of projects nudged forward by the arrival of some etchings from the UK. These will doubtless turn up here in due course, and the subject of this post is the first such.
The Rewanui incline was unusual in using a Fell system centre brake to deal with the steep grade. Both locomotives and vans were fitted with a gripping brake that bore on a raised centre rail between the tracks. Clearly, no model of the area would be complete without this prominent feature of the permanent way.
There are a couple of issues to cogitate upon though:
- The prototype centre rail sat on some unique little stools. Making a couple of hundred of these is not trivial.
- Rolling stock has not been constructed to run over a raised central rail. The WE does have a cut out cowcatcher as per the prototype, but it has an unprototypical gearbox driving the wheels.
- A centre rail really limits the running of unprototypical vehicles.
Drawings for the stools came my way via Mark Andrews and Ferrymead. Etching the things in brass was feasible, although there are still an awful lot to install even so.
Looking at the dimensions, the centre rail is not as prominent as I first thought. In addition the stools sit on a substantial baulk of timber 2mm thick in 1/64. To cut a long story short, by reducing the thickness of the timber baulk and using bedplates (as per the prototype), It is possible to retain the appearance of the real track as well as allowing clearances that work in the model.
Fortunately, the visiting locos on the layout are generally going to be West Coast types, as this is the prevailing fashion around here. Also, if I really must run something odd, I can run it from the ‘bins’ road of the fiddle yard to the station, thus avoiding the incline. So no problem there.
So how does it look?
The fell rail test piece
The picture shows my test piece. This took all afternoon to do, and it’s no longer than what you can see here – whew! However, there is some jigging that can be done to speed things up a bit and I only need a little more than a metre, so it should be OK.
One thing I will have to think about is my Fell vans. These actually have the brake modelled – so I’m going to have to look at the clearances there.
Overall I’m pretty happy. This is a major step forward for the layout, as it’s a hurdle pretty much unique to my model.
Stay tuned for a number of other interesting developments.
Lawrence
