Bath Spa - High tech modelling: Bringing 1947 into the 21st century. 3d printed scenery, cnc milled track, laser cut baseboards and computer control

[Siberian Snooper]

Hand built track using Templot templates gets my vote every time.

 

SS

[Rabs]

Ok, a question on the shunting.  Horse shunting in 2mm isn't going to be possible but I think the layout would be missing some of its character if the wagon sidings were purely decorative.  How unrealistic would it be for me, for the sake of my model, pretend that Bath used powered capstan shunting instead?  

 

I know that Moor Street used powered capstans for shunting: http://warwickshirerailways.com/gwr/gwrms1696.htm (the capstans were even made in Bath!)

 

I have a cunning plan for having wagon shunting with capstans and think that it could add a lot to making the station seem 'real', but I am concerned that it might be too much of a departure from what really happened.

Edited June 15, 2013 by Rabs

[Southernboy]

Shunting with N gauge capstans is a very interesting proposition and an aspect of your layout I'd be particularly interested to see developed.

 

Whether to do it or not is a personal judgement call of course - but if it were me I'd have no problem, seeing it as one of those 'necessary compromises' many modellers make on their layouts.

 

Out of interest have you decided on what you will use to represent rope? It's the one detail people will focus on seeing as it would be such an unusual and interesting feature.

 

Either way, just to say I've been enjoying following progress since you started this thread and wish you good luck - I think you have a great plan and look forward to seeing Bath Spa unfold

[Rabs]

Human hair!

 

To be honest, if I go down this route I wasn't planning to include the rope - it would be an absolute pain in the neck to operate and practically invisible from any sensible viewing distance.  My idea is to have a set of moving magnets under the trackbed to shuffle the wagons about (steel axles or another magnet on their underside).  I'd then have dummy, but motorised, capstans rotating in sync with the movement.  I'm going to try it on a test board and see if it is a convincing effect or if it looks too 'ghostly' without a visible rope.

[Vanders]

I'm a bit late to the party, but I went for hand laid turnouts and fiNetrax on my layout, and I can't recommend it highly enough. The only issues I had was that there doesn't seem to be any decent roller gauges for 9mm gauge code 40, which is a bit of a pain, but not an insurmountable problem.

Edited June 15, 2013 by Vanders

[clecklewyke]

Rabs said: I'm not sure where you mean by the bottom left corner.

 

I meant this - taken from a very early drawing.

 

But you seem to have moved on from then. I do hope you soften the edges as you described. Super stuff!

 

Ian

[Rabs]

Ah, I see where you mean now.  That is just an embankment, so it's ok to split it, I think.  There is a retaining wall around the edge of the track and then the land slopes down away from the viewer and into the central hole.  I'll know for sure when I get there!

[Joseph_Pestell]

I'm a bit late to the party, but I went for hand laid turnouts and fiNetrax on my layout, and I can't recommend it highly enough. The only issues I had was that there doesn't seem to be any decent roller gauges for 9mm gauge code 40, which is a bit of a pain, but not an insurmountable problem.

I'm sure you should be able to get gauges for Code 40/9mm in the US. Micro-Engineering???

[Rabs]

Luckily I have my lathe, so turning some roller gauges is no problem.

[Tim V]

I just remembered your query regarding contours in urban areas, have you looked at OSM data?

http://www.openstreetmap.org/

[Rabs]

Yes, thank you.  That, plus the OS benchmark register has given me enough information to get the landscape good enough for my purposes.

 

I'm making some progress with modelling skew bridge for 3d printing and my wagon shunting mechanism.  I'll post some pictures of the former this evening.  I'm currently waiting on a mini electromagnet for the latter.  If this proves strong enough to drag a wagon about from below the baseboard then I'll design the mechanism to move it about.

 

Whatever happens I will need 3 wagon turntables and none of my references show what they look like.  For now I'm going to assume that they were the typical 15ft steel plate type.  If anyone knows better, or has any pictures, I'd be grateful.  The only picture I can find of this area is taken from the up platform, so is at a low angle across the loading area on the south side.

[Rabs]

Here is one of the many interesting structures around Bath station.  Skew bridge, just to the west of the station, crosses the river at a very oblique angle.  Two very good photos of the structure are here:

http://www.flickr.com/photos/25876334@N00/3049138640/in/photostream/

http://www.flickr.com/photos/25876334@N00/3048298083/in/photostream/

 

And you can just see the end of it on the photo in my opening post in this thread.

 

It's a complex steel lattice, and as I'm not Ron Heggs I don't have the skill to build it piece by piece.  Luckily I have a 3d printer and a CNC mill, either of which can probably have a good stab at it.  Here is the bridge drawn up in Sketchup.  I really should be using Solidworks for this but I'm just so much more familiar with Sketchup.

 

 

 

I did this by finding photos of the bridge, correcting the perspective using GIMP2 to recreate a square-on view, and then drawing up the parts in Sketchup.  Here is one of the lattices part way thorugh that process before I added the rivets:

 

Once I was happy with the structure I then fattened up a few of the struts and exported it as an .stl for printing.  Imported into my B9Creator's layout software is one half of the structure:

 

I'm going to try printing it at the weekend (15 hours to print!), and we'll see how we do.

Edited June 28, 2013 by Rabs

[Tim V]

Isn't that the replacement bridge from 1960? Somewhere is a picture of the original bridge, but I can't remember where!

 

Have you got "Steam Around Bath" Mike Arlett & Ivo Peters ISBN 0948975075. Picture of the turntable on the down side in there.

[RailWest]

I'm glad you found that picture Tim, 'cos I couldn't !

 

Certainly IIRC the skew bridge was renewed in BR days.

[Rabs]

It was reinforcedin the 60s, but the current design dates back to 1878, when Brunel's original timber arch bridge was replaced.  See near the bottom of this page:

http://www.bathheritagewatchdog.org/brunel.htm

and a planning report here:

http://idox.bathnes.gov.uk/WAM/doc/Report-393962.pdf?extension=.pdf&id=393962&location=VOLUME2&contentType=application/pdf&pageCount=1

 

Also photos of it in the 20s and 30s here:

http://www.britainfromabove.org.uk/image/epw001161?search=bath&ref=1

http://www.britainfromabove.org.uk/image/epw001169?search=bath&ref=0

http://www.britainfromabove.org.uk/image/epw001953?search=bath%20station&ref=3

http://www.britainfromabove.org.uk/image/epw033153?search=bath&ref=47

 

 

 I'm sure that some of the detail will be wrong such as the L and U shaped braces which I imagine were part of the 60s upgrade because they are simply bolted onto the front while most of the braces are flat steel.  Unfortunately I don't have any contemporary photos which are good enough to work from but I thought  it would be better to accurately model a slight anachronism rather than wing it and make it up.  Fundamentally it is the right bridge though (although you did have me worried for a moment!)

[Tim V]

Fair enough - so long as you're happy!

 

If you are modelling the viaduct by the Old Bridge, there was an arch there used by the Home Guard in the Second war, how do I know - my Grandfather was in the home guard!

[Rabs]

First bits off the printer.  These are the various pillars and struts of the central bridge pier.  The square section one has come out nicely, with good detail around the L-angle diagonal struts (0.4mm wall, 1.5mm web ) and the trinagular gusset plates:

 

The round pillars themselves have come out nicely, but the steel truss of L-angle between them proved to be slightly too thin (0.2mm thickness, 0.5mm web)

 

I'm trying these parts again.  Once these are done I'll try the main truss.

Edited June 29, 2013 by Rabs

[Rabs]

Isn't that the replacement bridge from 1960? Somewhere is a picture of the original bridge, but I can't remember where!

 

Have you got "Steam Around Bath" Mike Arlett & Ivo Peters ISBN 0948975075. Picture of the turntable on the down side in there.

 

I do, thanks.  That photo is very helpful but it's at such a low angle it is hard to work out what the turntable itself looks like.   What do you think of this:

 

 

 

The first picture is fairly close to the angle of Peters' photo 1 from Steam around Bath.  The rails are just roughly positioned at the moment, I'm trying to get the plate correct.

 

As I will be running a limited set of wagons on these and wagon back to backs are easy to adjust (unlike some locos) I will try to reduce the flange way on the turntable because it looks a bit odd at the moment.  Although, on the computer with virtual lighting these things always look odd - I suspect that in the flesh and when painted and weathered it will look much better.  It's easy to forget that the whole thing is only 26mm across!

Edited June 30, 2013 by Rabs

[Tim V]

Looks pretty good.

 

Somewhere are pictures of the turntable at Swindon, with broad gauge still on it, and pictures of the turntables at Charfield and Yate. OK they are ex Midland, but might be worth a look.

[Rabs]

Oh, good point about broad gauge.  I wonder if the turntables would have been modified, or replaced?  My design isn't very plausible for a conversion job.

[HillsideDepot]

The Middleton Press book Swindon to Bristol via Bath in their Western Mainlines series has a shot (plate 69) of a turntable on the down side which might help, if you haven't already seen it.

 

The turntable is similar to the one you have drawn, but doesn't have the plate work at right angles to the rails, rather the strips carry on across the whole table, but have the appearance of being wooden battens just fastened on, rather haphazardly (dare I say that of the Great Western?). The photo is dated July 1949. It's not a great shot, but I guess any little helps.

 

Edit:

Just turned back a page to plate 67 which has a photo of part of the "engine shed" for the shunting horse on the up side.

Edited June 30, 2013 by HillsideDepot

[Siberian Snooper]

The Wagon turntables within Devonport Dockyard had track at right angles to each other on the turntable.

 

SS

[Rabs]

The Middleton Press book Swindon to Bristol via Bath in their Western Mainlines series has a shot (plate 69) of a turntable on the down side which might help, if you haven't already seen it.

 

The turntable is similar to the one you have drawn, but doesn't have the plate work at right angles to the rails, rather the strips carry on across the whole table, but have the appearance of being wooden battens just fastened on, rather haphazardly (dare I say that of the Great Western?). The photo is dated July 1949. It's not a great shot, but I guess any little helps.

 

Edit:

Just turned back a page to plate 67 which has a photo of part of the "engine shed" for the shunting horse on the up side.

 

Thanks, I've been working from a photo of the turntable on the down side, by Ivo Peters from "Steam around Bath" but it is at a very shallow angle (similar to my first CAD image above) so I've had to speculate what it looks like in detail.  Is the photo in your book from a better angle?  If yes I'll look into getting a copy.  Does that book have other useful photos of the station?

 

The Wagon turntables within Devonport Dockyard had track at right angles to each other on the turntable.

 

SS

 

Yes, both single and double (perpendicular) track wagon turntables seem to have been quite common.  I'm fairly sure that this particular one is a single set of rails though.  Cheers

 

[richbrummitt]

I have pictures of the TT that is at Didcot. It's a wooden type with perpendicular rails but I think it used to broad gauge. They're easy to dig out if they'd be of use?

[Rabs]

They certainly can't hurt, thank you.  I would also be interesting to see features like the retaining ring around the edge, so I'm sure your photos would be very useful even if I model a different turntable surface.