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Phil's Virtual Signal Workbench


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  • RMweb Gold

I had the idea to try to 3D print complete signals.

 

If it works this should have the following advantages:

  1. The software and the printer will do all the fiddly work of joining all the parts together. This will be helpful for those of us who are cack-handed but who need custom signals.
  2. It will allow an infinite variety of signal combinations to be created, just like the prototypes. Thus not relying on the limited combinations supplied by RTR manufacturers and not having to kit-bash parts together or scratch-build.

 

As you might guess these will be non-operating signals at first. If the idea works at all I will go on to try to make them operational.

 

I'm concentrating on "old pattern" GWR semaphore signals as described in the book "GWR Signalling Practice" by Smith and the Great Western Study Group.

 

The railway companies of course made standard parts and the engineers then took those parts and used them as-is or adapted them for the local situation. So if we create the same standard parts in software we should be able to build the entire multitude of prototype combinations. If your favourite station had a particularly unique signal that is characteristic of the place, then this technique might make it easier for you to have a model of that signal - if it works...

 

The first job is to create models of a small subset of the standard signal fittings from the descriptions, drawings and the very useful 1908 GWR documents reproduced in Appendix 2 of the book. Once I have enough parts I will assemble a fairly ordinary complete signal (in the modelling program) and start trying to print it! (I know next to nothing about 3D printing.)

 

I would prefer to be creating the models in Autodesk Fusion 360 but at the moment I can't even download it... :rolleyes: So I'm using Sketchup Make for now. This may be the first dead-end...

 

This will be an ongoing thread - and be warned: It might not go anywhere!!

 

Here was the kit of parts as of a few days ago:

1910098708_gwroldpattern14.png.b35839f731b18b0db55915507db2ce94.png

 

And here's the top of a 26ft Distant with a 5ft arm and some new parts added: Arm stop, Lamp bracket and Lamp (still both under construction).

754248395_gwroldpattern15.png.33b0eb069a846f68668988c5b2df656e.png

 

There are still lots of parts to make and lots of things to correct. (Since I added the arm stop I now understand why the boss plate casting is the shape that it is and why my models of them are wrong!)

 

If nothing else, this will be an amazing learning experience for me!

 

Edited by Harlequin
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  • RMweb Gold

 this will be very interesting, especially as some of the parts are so fiddly. It will be interesting to see how the printer handles this. 

My only immediate observation is that real signal arms are generally pressed out of sheet metal and i wonder how the 3d process will cope. That is why most models use etched arms.

However, for posts, brackets, treads, handrails, finials  etc etc, looks good.

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  • RMweb Gold
16 minutes ago, ikcdab said:

 this will be very interesting, especially as some of the parts are so fiddly. It will be interesting to see how the printer handles this. 

My only immediate observation is that real signal arms are generally pressed out of sheet metal and i wonder how the 3d process will cope. That is why most models use etched arms.

However, for posts, brackets, treads, handrails, finials  etc etc, looks good.

 

Thanks. The signal arms I'm modelling at the moment were wooden. 12 inches wide tapering down to 11 at the boss and half an inch thick tapering out to 1 inch thick at the boss. (Opposing tapers in the two dimensions...)

 

Half an inch in 4mm scale is 167 microns (if my maths is right) and that should be within the capability of my printer.

 

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  • RMweb Gold

Added the "Blinker" and a basic top stage in the Sketchup model.

1611730595_gwroldpattern18.png.061fa7ae1e2531a4b6fa3029ca6191bb.png

 

I have finally got Fusion 360 installed (the problem was with my Autodesk account) so I will have to move across to that but Sketchup is like an old friend...

 

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  • RMweb Gold
48 minutes ago, Junctionmad said:

whats the intended scale and what 3D printer are you going to use 

4mm, AnyCubic Photon S. (Build volume 115 by 65 by 165mm. Z resolution 10 micrometres.)

 

I realise that I will need to adjust the thickness of some parts but for now I'm creating the model using real-world dimensions as an idealised starting point.

 

Edited by Harlequin
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Phil

 

You are heading down the right track with the various parts drawn as separate components but as you have noted you will definitely have to thicken some of the parts for structural strength and print-ability.

 

I have been drawing and selling a range of HO 3D printed signals for the New South Wales Government Railways (Australia) since 2014. I have a Shapeways shop and began having the signals printed in the White Versatile Plastic with Fine Detail Plastic detail parts such as arms finials, rear lamp blinds, counterweight levers, etc. Of course the Versatile Plastic is low resolution but has the advantage of being flexible and the Fine Detail Plastic is high resolution but is fragile.

 

I later added signals in Fine Detail Plastic and finally in brass.

 

Given the Shapeways price increases and the drop in our dollar over the last couple of years I finally began a range of lost wax cast signals made locally that are much cheaper than Shapeways.

 

I am not trying to push my signal range here as UK modellers would not be interested, just wanted to let you know that it will be an interesting journey.

 

I have just tried uploading two JPG files that are less than 1MB but they failed to load so I can only point you to my Signals Branch blog for a photo or two. Annoying!

 

 

 

Bracket Signal Castings.jpg

Bracket RH 39-36 inch Arms.jpg

Edited by RayP
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  • RMweb Gold

Balance lever plate, balance lever and weight with connection to down rod:

419957280_gwroldpattern24.png.7dc498025bbba0022af96a4297e934e7.png

 

Some of these bits will need to be improved later. (And I should really fix everything together with bolts and screws...)

 

Edited by Harlequin
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  • RMweb Gold

The art of printing...

 

Here is print number 2. (I won't show you print number 1...)

IMG_20200411_172307.jpg.c4e0acad92e79b9cdfd2320134b26f1b.jpg

 

IMG_20200411_172629.jpg.73e497a1a5b76178b155dca191b08245.jpg

 

The spectacle plate and ladder were much better in print #1 but both prints are covered in unwanted gloopy gunky bits. This may be caused by the very fine parts that have become disconnected during printing.

 

Amazingly both prints have successfully reproduced the very fine upright rods (5/8th inch in real life) which support the top platform's guard rail.

 

I need to experiment further.

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  • RMweb Gold

Still very much in the learning phase but things are improving. This is print #4 straight out of the printer with supports still in place:

IMG_20200527_205005.jpg.a193d1bb198d45caa2772831ee17fc84.jpg

 

And after an hour or so of very careful chopping and trimming:

IMG_20200527_230603.jpg.da4e1e1bf09b059b1a3a5ea7e3568ac7.jpgIMG_20200527_230339.jpg.e9d3995b6a77b1eb6ddde4114e8eb0f9.jpg

 

Nothing has been deliberately thickened yet, it's all to scale and amazingly, the 5/8ths inch vertical rods supporting the guard rail have printed successfully. They are incredibly fragile and somewhat warped, though!

Notice also that the ball in the finial is hollow.

Annoyingly, the peak of the finial seems to have been truncated and the ladder is a mess and not connected to the landing.

 

This print is sharper than previous ones and that's because I moved the printer into a room with no windows and kept the door shut so that no UV light could affect the resin during the print.

 

Onwards...

 

Edited by Harlequin
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