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

[Izzy]

Yes, I was thinking about the glue bond. I have found it can be weakend by too much heat, (you can of course lift the copper completely by applying enough heat!), yet still hold things together until sufficient forces arise that break it, thermal expansion/contraction, being caught/knocked etc. Having suffered in this way in the past, and found that generally c/c track with chairplates seems to be stronger and more resistant to these effects, I thought I'd mention it, as once the copper lifts than your a bit, you know........... which then brings you back to driving pins in etc.

 

I'm currently reviewing baseboard joints in 2FS and how best to re-arrange them on an already built layout, with the thoughts that small home machined rivets fitted into the pcb (similar to ply/riveted) with cosmetic chairs might be a more easily repairable arrangement in the case of damage.  

 

Izzy

[Rabs]

A bit more fun on my lathe.  These are some parts for the first of three wagon turntables I need around the station.  The design is made more complicated by wanting to get an electromagnet within a few mm of the underside of the track, so I can't just run it on an axle. 

The ring component is turned from 1.2mm brass sheet and will be glued to the baseboard and.  This thickness matches the sleepers of the track that I'm using so i can just solder the rails to the top of this part. 

The disc is a snug fit inside this and will be connected (by a cranked arm) to a stepper motor below.

Edited October 25, 2013 by Rabs

[Portchullin Tatty]

All very interesting stuff and others have said, some of these modern techniques are going to transform our modelling - although I would imagine they are terrifying some!

 

Keep up the good work - it is inspiring and interesting.

[Rabs]

I've just been working my way through the WTT for Bath.  I can't find one for 1947, but I'm expecting the 1948 one written immediately after nationalisation to be pretty representative.  It looks like Bath saw 81 trains a day in the Down direction on most weekdays.  I've not gone through the Up timetable yet, but I assume that it will be a similar number.  I think that I might need some more stock and some James Bond style revolving number plates for my locos!

 

One interesting thing I hadn't appreciated before was that Bath was sometimes served by slip coaches off express trains running the Paddington to Bristol route.  That should be fun to model!  I'll need some on-board DCC uncouplers.

 

Does anyone know how far up the line the uncoupling would usually be done for slip services?

 

Also, the station speed limit at Bath was 30mph, so I imagine that the whole train would slow to this speed before uncoupling the slip carriages - I don't imagine that braking the leading train after detaching coaches would be a good idea!

 

EDIT: I just found this website: http://mikes.railhistory.railfan.net/r134.html, which shows an action shot of a slip off the Bristol express at Bath - what a stroke of luck!.  Judging by the livery this is c.1930 and from the buildings in the background I will be able to work out pretty accurately where the detachment has occured.  So the only question remaining is what speed was the train doing when the slip happened, given that it has to go through the station at 30mph just a mile or so further up the track.  Unless anyone can correct me I'm going to assume that it had already slowed to 30 before detaching the slip coaches.

Edited October 26, 2013 by Rabs

[Howard]

Track at the baseboard join after laying, cutting, disassembly, getting bashed around a bit to test how strong the rail ends are and finally bolted back together on an uneven floor.  Looks pretty well aligned to me.

How are you going to ballast, now you've removed the sleepers from between the rails?

[Tim V]

Interesting picture of the slip coach, but I cannot work out where it was taken. It looks like it's heading away from Bath with that background.

[jjnewitt]

Interesting picture of the slip coach, but I cannot work out where it was taken. It looks like it's heading away from Bath with that background.

The buildings in the background look like the area around the bottom of Bathwick Hill to me. I think the photo was taken somewhere between the bridge over the Avon on the eastern side of the station and the bridge over the A36.

 

Justin

[Rabs]

 

How are you going to ballast, now you've removed the sleepers from between the rails?

 

I haven't removed the sleepers completely - just the 35micron thick layer of copper from the top surface of them.

 

 

The buildings in the background look like the area around the bottom of Bathwick Hill to me. I think the photo was taken somewhere between the bridge over the Avon on the eastern side of the station and the bridge over the A36.

 

Justin

 

That was my conclusion too.  It's a down train approaching Bath on the arches to the East of the station - I've got other photos from a similar angle with the same houses in the background.  It has to be going towards Bath because that's where the slip coaches are due to stop.  Judging from the angle I believe the train is about level with the cricket ground at this point.  This suggests that the detachment occurred somewhere around the bridge over the Pulteney Road (A36).  Nicely in my modelled area

Edited October 27, 2013 by Rabs

[Howard]

I haven't removed the sleepers completely - just the 35micron thick layer of copper from the top surface of them.

Ah, I missed that.

 

It means you don't have a gap in the middle of the sleeper to fil. Also - if you've got the geometry right - the copper lifts the track above the sleepers so the sleepers will be (can be) the same height as the fiNetrax ones.

Howard.

[Rabs]

Ah, I missed that.

 

It means you don't have a gap in the middle of the sleeper to fil. Also - if you've got the geometry right - the copper lifts the track above the sleepers so the sleepers will be (can be) the same height as the fiNetrax ones.

Howard.

 

That's the plan.  It's not quite perfectly the same height, but I'm happy that it's good enough.  Once painted and weathered it should blend in nicely.

 

In the meantime tracklaying has continued at a slow but steady pace:

 

The traverser is coming together nicely.  The first step was to mill a copperclad base which spans both the join between the module and the sliding join on the traverser module.  Here it is rested in place:

 

Next, a thin coat of epoxy on the underside and weighted down:

 

I then laid the through tracks before making the two cuts.  And here it is as it stands at the moment:

[shanks522]

A very ingenious traverser indeed, this whole thread facinates me with some very clever construction techniques.

 

Graham. 

[ianwales]

I've just been working my way through the WTT for Bath.  I can't find one for 1947, but I'm expecting the 1948 one written immediately after nationalisation to be pretty representative.  It looks like Bath saw 81 trains a day in the Down direction on most weekdays.  I've not gone through the Up timetable yet, but I assume that it will be a similar number.  I think that I might need some more stock and some James Bond style revolving number plates for my locos!

 

One interesting thing I hadn't appreciated before was that Bath was sometimes served by slip coaches off express trains running the Paddington to Bristol route.  That should be fun to model!  I'll need some on-board DCC uncouplers.

 

Does anyone know how far up the line the uncoupling would usually be done for slip services?

 

Also, the station speed limit at Bath was 30mph, so I imagine that the whole train would slow to this speed before uncoupling the slip carriages - I don't imagine that braking the leading train after detaching coaches would be a good idea!

 

EDIT: I just found this website: http://mikes.railhistory.railfan.net/r134.html, which shows an action shot of a slip off the Bristol express at Bath - what a stroke of luck!.  Judging by the livery this is c.1930 and from the buildings in the background I will be able to work out pretty accurately where the detachment has occured.  So the only question remaining is what speed was the train doing when the slip happened, given that it has to go through the station at 30mph just a mile or so further up the track.  Unless anyone can correct me I'm going to assume that it had already slowed to 30 before detaching the slip coaches.

 

Hi

 

There was an article in a 1970's Model Railway Constructor written by Newport MRS on how they had a working slip coach on their Long Suffren layout, may be of some use to you,

 

Ian

[tender]

Ah, just seen the light. I've been pondering over how your Traverser worked, the last set of pictures makes it very clear now. Very ingenious. Love your workshop facilities, must be the envy of many including me.

Keep the posts coming.

[Rabs]

The postman has just deliverd my copy of Colin Maggs' "The GWR Bristol to Bath Line".  I wasn't sure how useful it would be when I ordered it but I'm glad I did.  A decent proportion of the book is based around Bath, and the majority of the photos are useful in one way or another.  A few highlights I might choose to incorporate:

 

A GWR diver in classic bell-helmet climbing out of the river after inspecting the skew bridge piers below the waterline.

 

Various experimental and one off locomotives at the station:

• Great Bear
• the trial streamlined Castle and King of the mid 30s
• La France
• the 4-4-2 Saint prototype (before conversion to 4-6-0)
• the GWR's first pannier tank (1490, a 4-4-0), which ended it's career as Bath's shunting loco
• A special excursion train from Fry's chocolate factory to London adorned with flags.

Lots of useful pictures of prototypical train formations (particularly some difficult to find freight trains)

 

A GWR livery scarab in front of the station building

 

A whole host of beautiful outside frame locomotives

 

 

All in all, I think that I'm going to have to allow myself some more flexibility on dates, I can't miss out on some of the gems that went through Bath in earlier times!

Edited October 30, 2013 by Rabs

[BG John]

If you're considering flexing the date a bit, how about going back to 1847 before it's too late! Think of all the wonderful machining you could do to produce broad gauge baulk road!!!!

[Rabs]

The thought had crossed my mind!  I'd love to do the mixed gauge period as well.  Unfortunately I just don't think that my personal interpretation of Rule 1 would allow me to run post-WWII liveries (which is most of my stock at the moment), on mixed gauge track.  I'll save that for another layout I think.

Edited October 30, 2013 by Rabs

[BG John]

I suppose you could modify your existing CAD files, and knock out a broad gauge version when you've finished this one!

[Rabs]

I finished the test cassette yesterday.  I had planned to use track on these, but decided that aluminium angle would be a better bet. This will be stronger, easier to clean and also helps to prevent rolling stock from making a bid for freedom when I'm moving these around.

 

A cassette in the storage area:

 

In transit with the doors closed:

 

Doors held open magnetically and stock ready to roll:

[Howard]

I don't see any screws between the aluminium and the wood - I presume you are relying on glue. What adhesive have you used?

Howard.

[Rabs]

I don't see any screws between the aluminium and the wood - I presume you are relying on glue. What adhesive have you used?

Howard.

 

In that photo they are just resting in place for a test fit.  I'm going to use a thin layer of epoxy to join the aluminium to the ply.

[Rabs]

With help from my wife and despite 'help' from the cats today I got the first scenic modules mapped out.  This involved setting up a digital projector with the sketchup plan projected onto the boards at the other end of the room.  We then traced the outlines for the buildings and the roads.

 

To be honest this might not have been all that useful because it took a while to set up and the transcribing probably wasn't that accurate.  Also the plan isn't all that detailed yet so what we have drawn might not even be all that accurate. It was fun but I think I'll stick to printing and gluing plans for the other boards.

[Rabs]

Yesterday I added the stepper motor drive for the traverser module:

 

This involved turning a little coupler to adapt the shaft of the stepper motor onto the leadscrew and then a delrin bush bearing for the other end:

 

In other news: I've been planning to use printed photo scenery (similar to scalescenes by from my own artwork).  However, I was concerned about the fading of inks from my inkjet printer.  To test this ,back in August, I printed some sections of wall.  One of these I sprayed with matt varnish and one I left uncoated.  I then left them both on a south facing windowsill for ~3 months.  Yesterday I also printed a fresh copy with the same settings for comparison:

 

As you can see, the one without the varnish has, as I expected, faded badly.  Particularly the red tones have been lost.  However, there is also noticeable fading of the varnished one, relative to the fresh print.  Now, this may be because I only did one coat but it has made me quite hesitant to use my printer.  I'm going to look at using the low cost photo printing offers from companies like photobox, as they use better, archival quality inks and should survive better.

Edited November 6, 2013 by Rabs

[Indomitable026]

I finished the test cassette yesterday.  I had planned to use track on these, but decided that aluminium angle would be a better bet. This will be stronger, easier to clean and also helps to prevent rolling stock from making a bid for freedom when I'm moving these around.

 

A cassette in the storage area:

2013-10-31 23.04.43.jpg

 

In transit with the doors closed:

2013-10-31 23.05.20.jpg

 

Doors held open magnetically and stock ready to roll:

2013-10-31 23.05.50.jpg

 

This is good stuff mate.

 

Are you going to coat the plywood with anything to keep moisture out?

[Rabs]

This is good stuff mate.

 

Are you going to coat the plywood with anything to keep moisture out?

 

Thanks.  I wasn't going to, no.  I spent a while reading up about people's experiences and the conclusion seemed to be that if you use decent quality ply and don't incorporate any softwood into the design then moisture shouldn't be an issue.  Do you agree?

[artizen]

My experiences with ply is that it will curl when affected by damp. Mind you we do experience a monsoon season around about now for the next four months.

 

Getting back to ink fade - the paper can have a bearing on the life of the printed image as well. Cheap photocopier paper as used by most of us in our desktop inkjet printers is doing the ink no favours due to impurities and "built to a budget" pricing. Using the HP 44 inch inkjet sitting next to me I can get a half decent result on bond paper but to be sure, I keep my layout covered (mostly for dust and bugs, but also for light fade). The bond paper image will eventually fade away but then I just run the file again....

 

I have tried matte photo paper on the best setting on my desktop inkjet printer and the results were spectacularly good but the paper is just too thick for modelling. Maybe try finding a high quality bleached white thicker office paper (primarily sold as quality paper for letterheads in the printing industry). Bleached is bad for the ecology but unbleached tends to leave just a few too many impurities behind. Failing all that, try sourcing a proper inkjet paper instead of just photocopier paper.