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

[Lawrence@NZFinescale]

A bit more work on Wa217, which I can now present on it's wheels

I fixed and quartered up the wheelsets.  It was all jigged and ran beautifully first time with tight clearances on the crankpins.  As it should, but it's always a relief to get right.  It's an area I've struggled with over the years, but I've now engineered out almost all the variables to avoid having to hold my tongue in any particular position.

There are still temporary pins in the valve gear and some screws that need shortening.

As may have been mentioned before, the rods are cast with slots into which separate cast brasses can be fitted.  This allows for a very nice looking rod that can be adjusted accurately for length in a jig.  This works really well for larger locomotives, but a bit more of a fiddle on the Wa where everything is a little smaller.  Crankpins are turned on the cast wheels, so are accurate.  They will be retained by M1 screws.  The leading crankpin is more or less how they will look when done, albeit with the screw head filled flush.

This is a split frame loco, so isolating everything requires some thought.  It's an evolving method that I've played with a lot, so not too much of a headache.  The live frames only extend from the footsteps to mid-cylinder.  The frames at either end being part of the body.  This gives a strong structure at headstock/cowcatcher and the frame join is relatively easy to hide.  The trucks were tricky with metal wheels so I turned up some delrin pinpoint bearings rather than the usual brass.  The truck frames should be neutral, but everything is rather tight so I'll have to check and fettle to make sure there are no shorts on curves.

The next job will be adding the brake gear, another potential electrical isolation nightmare that has vexed me in the past.  It is also complicated by the fact that the stretchers are curved up and over the centre rail.  This precludes using thin PC board for isolation.  On the plus side, if the shoes touch the wheels it can only improve pickup.  Brake spacing is something to get right though as close spacing looks great, but experience shows that scale brakes are VERY effective if they are too close.

This time around I have some new ideas that I'm confident will make this a whole lot easier.

[finescalerr]

It looks as though you face a few challenges but the model is certainly quite adequate at this stage. -- Russ

[Stuart]

Love the detail.  An amazing web of piping you have created.

[Peter_T1958]

Absolutly perfect in implementation but also a lovely subject! 

[Bill Gill]

That's quite a challenge, but it sounds like you have it well thought out and under control. It's looking terrific.

[Hauk]

Make no mistake, this is of course an absolutely beautiful model.
But I can not resist playing the devils advocate for a second:
A pattern maker like the late Cliff Grandt or Charles H. Brommer would have made sure you could count the individual leaf spring blades above the pilot wheelset...

[Lawrence@NZFinescale]

Make no mistake, this is of course an absolutely beautiful model.
But I can not resist playing the devils advocate for a second:
A pattern maker like the late Cliff Grandt or Charles H. Brommer would have made sure you could count the individual leaf spring blades above the pilot wheelset...

It is a bit of a disappointment...

And it does raise a philosophical point.  In the CAD model leaves are separate - but the leaves are 3/8" or 0.15mm scale.  I've accentuated the edges as you can see.  Even so the groove representing the edges of the leaves is only a voxel or two deep.  Essentially I'm trying to resolve details that are at the limit of resolution.  If I could get the detail super sharp, I'd also be getting super sharp voxel/layer resolution which isn't necessarily an improvement as smooth surfaces end up stepped.

Similar springs done at 1:48 (3rd image) as opposed to 1:64 resolve beautifully.  The 1:64 springs do resolve if you magnify the image (attached) just not as sharply. It's not the best casting either.  But even a good one barely shows separation.

In fact, looking at images of the real thing the spring leaves do not look dramatically separate either.  So you start getting into the realm of art, accentuating detail so that the eye is pleased, but the model is not technically accurate. The whole thing becomes a bit subjective. This is from a 35u resolution printer.  My next upgrade will likely be to something around 20u, which would produce better base prints.

When I weather it I may be able to bring out those subtle separate laminations :-)

[Barney]

Now Thats Quality !!
After time Leaf springs on Greasy /oily things become one its only the ends that show it has separate leaves or is it leafs ! So viewing from a reasonable distance I don't really think you would notice - This is from my experience of many many years ago as an apprentice car/truck mechanic (Grease monkey I don't think its aloud to call the upstarts that now )
If You had not made the early morning tea got the sandwiches / toast that morning you was put on Grease monkey spring greasing  or oil can crushing duties. 
Barney

[Lawrence@NZFinescale]

Following Hauk's cruel ( ) critique I feel the urge to defend my pattern making...

20 odd years ago I did a kit for the Baldwin Wb.  This was before 3D prints were readily available, of course.  The Wb has a similar truck structure, which was fabricated from brass as a casting pattern.  In the  image castings shown tack soldered to a bar to facilitate drilling. I've done similar patterns for other things, typically etching the component parts to make life easier.  You can readily see the leaf separation in the springs ( ).

Ironically, in the Wb these springs are behind the wheels so are not really visible anyway.

Using a print/cast process to produce castings is relatively fast and easy.  There's no shrinkage to deal with, no constraints/cost of moulds, and considerably more flexibility in design.  But there are limitations to consider.  So I'm greatly enamoured of the process as it increases the volume and scope of what I can do, but I am a bit disappointed with those springs.  I might have to rework a better set for Hauk.

[finescalerr]

I suppose you could do that but maybe you should remember the scale of your model and then read Barney's post again. -- Russ

[Lawrence@NZFinescale]

I suppose you could do that but maybe you should remember the scale of your model and then read Barney's post again. -- Russ

Oh I know.  Refer to the first post in this thread too, which points out that each model is part of a far larger whole so pragmatism demands the odd fine detail be left out. I do agree with Barney too, but on more carefully viewing some photos, discrete leaves are quite clear.

However a) I'm curious if a few tweaks will improve things, and b) This is a 'commercial' ( ) pilot, so tweaks are appropriate.  I don't plan on replacing the trucks on 217, but I have 137 and 289 to do, so worth the 30 minutes or so to dabble with the model. I've done it, so I'll proceed to a test print.  I won't cast them unless the print is an improvement.

[Lawrence@NZFinescale]

Some small improvement perhaps.

This is the resin that will go away as the sacrificial 'wax' for investment casting.

Spring definition is there, but as can be seen it's hardly as visible as the layering from the printer.  The latter is essentially invisible in the casting, so not surprising the spring definition is poor as well.

Russ is quite right though.  These really are very small and at anything less than extreme magnification they are fit for purpose.

[Lawrence@NZFinescale]

Wa 217 with brakes fitted up.

A chance to try some new ideas that worked pretty well.

At the top the brake levers are free to pivot on 0.5mm wire shafts set in short lengths of tube soldered through the frames.  The 0.5mm wire is crimped inside the frames to retain things.  Levers and shoes are live to the wheels and frames.

The rodding is neutral.  There's a 0.6mm hole at the base of the lever into which is fitted an insulating PTFE (Teflon) bush.  The spigots at the end of the cross shafts are 0.3mm.  The cross shafts in this case are 0.5mm tube, though in future I'll modify my etch so they are the correctly shaped flat bar - not that you can see them.  The bushes are made from PTFE tube that is nominally 0.6mm od/0.3mm id.  In fact, it's a tad larger on both dimensions so it's a firm fit in the lever and free on the spigot, which is ideal.  Very easy to do as the tube is forced into the lever and trimmed to length with a scalpel.  The rodding assembly is easily removable, but sits in place securely.  This is an area where I've struggled in the past for a neat solution, and this is pretty much ideal on all fronts.

Everything still goes around, although there's a bit of fettling to do.  The next job will be to fit the operating cylinder and cranks.  The idea is to set things up so the shoes are quite close to the wheels, but avoiding any friction. 

[finescalerr]

It's coming together nicely. The precise detail suggests it could be 100% larger. -- Russ

[Ray Dunakin]

Looks great!