GVT Covered Goods Wagon

[Durley]

Hello All
My latest project has been this GVT covered goods wagon at 16mm/ft. Whilst my railway is 45mm gauge, I incorporated the ability to build the wagon for either 32 or 45mm gauge so I could share stock with my father who models at 32mm gauge.
The photos of the finished wagon (painted in undercoat) are of a 32mm gauge version using Slaters wheelsets, who supply the correct 29mm (scale 22” diameter) 7 curly spoke wheels. Binnie wheels also are the correct pattern and is what I will use for my 45mm gauge version, but are a little less refined in their appearance.
The body is 3d printed to my own design in one piece, with additional details (brakegear, axle boxes, central longitudinals, roof supports and corner plates) printed separately. The floor is 3mm thick Perspex and the roof is 2 sheets of 0.8mm ply laminated together.
I’ve milled two aluminium angle solebars/bearing holders which provided the structural mount for the wheel bearings. These aluminium pieces are screwed to the floor through slotted holes, allowing their positions to be adjusted for either 32 or 45mm wheelsets and also allowing the wheel side play to be fine tuned. The brakegear is mounted on a couple of M2 screws that are tapped into the aluminium side piece and held in place with nuts on either side, allowing the brakegear position to be altered to suit whatever wheels are fitted.
I’m happy to make the 3d print files available if anyone wants them but do note it’s been designed specifically for a resin (SLA) printer. I don’t have a filament printer so I’ve no idea if it would print on one of those. It needs a print bed approx 200mm x 100mm minimum to print the body at 16mm/ft scale. I have a Creality Halot Mage printer, but any resin printer with a 10” or bigger screen should be suitable.
I’ll update this thread to show the build steps on a 45mm gauge version that I am putting together now (not that there is much to it!).

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[ge_rik]

That's beautiful! Loads of intricate detail well executed.

Rik

[Peter Butler]

I agree with Rik, excellent job.

[philipy]

Superb!

[drewzero1]

Superb model, I especially like the details on the latch and brake gear!

It looks like it would probably print okay on an FDM printer, though some details may be tricky. The latch bar at least might need to be printed as a separate piece if it isn't already.

[ge_rik]

Superb model, I especially like the details on the latch and brake gear!

I agree. Looks as if it might actually function

Rik

[Durley]

Thanks for the kind comments.

The latch is all part of the body as you can see in the photo. Sorry about the colour, I’m using up my stock of flesh coloured resin!

I have already had a request for the files, so will make them available in the next few days on the 3D print area of the forum. If anyone fancies giving it a go in filament, I’d be interested to see the results.

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[StuartJ]

Very nice!

[drewzero1]

I'd love to give it a try on my FDM printer, but no rush on posting the files... It'll probably take me a bit to get around to trying it anyway.

[Durley]

I’ve gone on a slight deviation this weekend…
The Glyn Valley Tramway ran on somewhat unusual 2 foot 4 and a half inch gauge track (724mm) meaning that at 16mm/ft, 32mm gauge (scale 2 foot) is too narrow and 45mm (scale 2 foot 9 and three quarter inch) is too wide. My railway is 45mm gauge, which approximates to the GVT’s gauge at 19mm/ft or 1/16 scale (45mm x 16 = 720mm).
Apart from one odd-ball open carriage, all of the GVT’s rolling stock was under 12 foot long. 12 foot at 19mm/ft is 228mm which coincidently is the length of the print bed of my 3D printer. The two covered vans were actually longer than the other passenger carriages at 11 foot 10 and a half inch.
I could therefore design and 3D print any of the GVT rolling stock and have it running on correctly scaled rails, if I could successfully print something that large, which I had never tried before.
So I took a bravery pill, scaled up the van body by 118.75% (19/16) and set the printer off. 16 hours and 600ml of resin later, here’s the result:

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And a comparison against the 16mm/ft version:

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Wheels will be a bit of a compromise but the Slaters 7/8th scale range includes a 1'6" 6 Curly Spoke Wagon Wheel (Festiniog) wheel that works out at about the correct diameter, although is one spoke short to be prototypically accurate and has a much thicker tyre, but I can live with that.
https://slatersplastikard.com/linePage. ... id=2218FRC
I wonder if anyone else has modelled the GVT at 1/16th scale?

[drewzero1]

That works out to about 3/4 inch to the foot, I think. I have never heard of anyone specifically modelling the GVT at that scale but it does sound like it works out well between your printer volume and the track width. I'm curious to see what it looks like without compromising the gauge as we so often do!

[philipy]

Both of those vans are extremely impressive, both from the drawing and printing POV.

I think you said a while ago that you have a Creality Mage printer? The print bed is more or less the same size as my Phrozen Sonic Mighty 8k (237 x 127), so in theory I should be able to do much the same
Having said all that, it appears from your photos that you are printing the sidewall 'box' directly on the plate? If so, (a) how do you avoid the suction effects as it progresses down the box, and (b) how do you deal with the 'elephants foot' effect? Those have always been a problem for me and the only way I've found round them has been to stand the print off from the plate on supports, which then makes getting a clean bottom edge a bit of a 'mare - and adds to the print time!

[SimonWood]

That is a superb model. Beautifully drawn and detailed.

Thanks for making the files available, I will definitely give this a go in either resin or filament. Not sure which will be easier for me - I'm still finding resin a challenge, but I'm aware it's not designed for filament printing. That said, it'll be a while before I get a chance to have a go, no doubt drewzero1 will have had a go by then so I will learn from his experience...

[Lonsdaler]

Beautifully crisp detail there. As someone has said earlier, it actually looks like the door latching mechanism will work!

[Durley]

Having said all that, it appears from your photos that you are printing the sidewall 'box' directly on the plate? If so, (a) how do you avoid the suction effects as it progresses down the box, and (b) how do you deal with the 'elephants foot' effect? Those have always been a problem for me and the only way I've found round them has been to stand the print off from the plate on supports, which then makes getting a clean bottom edge a bit of a 'mare - and adds to the print time!

Hi Philip, yes I print directly from the bed of my Creality Halot Mage and have incorporated some features in the design to deal with the problems you correctly identify. Firstly there are vent channels in the headstock that allow resin to flow out as the build plate moves down into the vat and then relieves the suction as the plate moves up. 4 channels of about 3mm diameter appear to be sufficient for the 16mm/ft version. The channels are later covered over by a separate black plastic strip that represents the buffing plate, so are not visible unless you look at the underside of the model. Using black plasticard for the buffing plate has the advantage that were the paint to rub through, it would reveal black rather than the rather garish flesh coloured resin I have used!
To minimise the elephant foot effect, I have chamfered the bottom edge of the curb rail and headstock with a 0.5mm 45 degree chamfer. As I use 10 bottom layers with a layer height of 0.05mm, the elephant foot effect mostly just fills back in the chamfer, leaving very little material to sand back.
To ensure the model remains adhered to the build plate, I have added ‘ears’ to the corner of the model. These are just circular features 0.25mm high that are easily removed after curing by scoring with a scalpel and snapping. Without these ears, I do find the corners of the model can lift during printing leading to the bottom developing a slight curve. In addition there is a false floor inside, again just 0.25mm thick, that is removed after curing in the same way as the ears. This gives a huge bottom layer area (most of the build plate in fact) that is significantly greater than the area of subsequent layers, so ensures the model stays firmly stuck to the plate during printing.
I tidy up the print to remove any remaining elephants foot and remnants of the ears and false floor with a Perma-Grit tungsten carbide file. This chomps through the resin in quick time (used under a running tap to minimise dust), finishing with a finer sanding stick.
To avoid losing any detail in the clean up process, I have made some features low down on the body as separate pieces, to be glued on after the clean up. This explains the separate plates on the corners (representing the side extensions of the buffer plate) and missing bottom to the door posts, which I add back with printed parts and a strip of plasticard respectively. This makes clean up very straightforward as I am not trying the file around fine details.
You can see the vent channels in the headstock (arrowed) and ears in this screen grab from Fusion 360

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[philipy]

Thanks for the detailed reply.

Chamfering the bottom edge has worked for me for a nice rectangular shape but can be a bit problematical if there are changes in either the vertical or horizontal direction.

I hadn't thought of your drainage channels, but it makes perfect sense now you've said it! Thanks.

I understand your internal thin floor keeping things flat on the bed, but following on from that, why not simply print a 3 or 4mm floor with the drainage channels above it, rather than having to mess about with cutting and fitting perspex?

As you may have seen I've been drawing up some F & B 4-wheel coaches which also just fit on my build plate. You've now got me wondering if I dare try the body as one piece. Care to throw me some of your "bravery pills"?

[Durley]

I understand your internal thin floor keeping things flat on the bed, but following on from that, why not simply print a 3 or 4mm floor with the drainage channels above it, rather than having to mess about with cutting and fitting perspex?

As you may have seen I've been drawing up some F & B 4-wheel coaches which also just fit on my build plate. You've now got me wondering if I dare try the body as one piece. Care to throw me some of your "bravery pills"?

That would be another option Philip but the floor would need holes for the top part of the wheels to pass through. It would also need a different arrangement for the axle boxes and brake blocks.

Feel free to take a handful of my brave pills for your coaches…what is the worst that could happen?……… answering my own question, the print could drop off the build plate, smash the screen writing off the printer, puncture the bottom of the vat and leak resin everywhere, at least that what I was lying awake worrying about when I printed the 19mm/ft version

[Durley]

I have uploaded the STL files for 3D printing the model to this location for registered forum users only: viewtopic.php?t=15139

Please note licence conditions - commercial exploitation not permitted.

[drewzero1]

Thanks for sharing! I've downloaded the files and tested them out in the slicer, never tried printing a whole box at a time like that before so I think I'll need some of those bravery pills too... Time estimate for the body on my FDM printer is between 18 and 28 hours depending on options. At any rate, it doesn't look like details will be lost, but layer lines will be visible due to the orientation. I might try it over the weekend if I'll be home for long enough at any point.

[Durley]

Good luck drewzero1! Hopefully the layer lines will look ok and may actually pass off as wood grain effect on the planking.

I’m putting together a 45mm gauge one now so will post up the build steps as I progress.

Firstly, here’s all the parts printed off. The longitudinals and roof supports were printed flat on the build plate, other parts supported as shown using manual supports in the slicer software.

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