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

[Rabs]

Slow progress at the moment but the wiring for the first module is nearly done - just a couple more connections and I should be able to get something moving!

[Claude_Dreyfus]

Following the conversations on another forum about suitable motors for Finetrax points, I followed your link to this thread.

 

At the risk of yet another 'me too' post, there is some really innovative stuff going on here, to the highest quality. The extended arm on the point motor (post 118) to compensate for the viaduct is exactly what I was looking for to fit my embryonic layout design - albeit my plan involves an overbridge and embankment.

 

Looking forward to seeing how else I can be inspired!   

Edited February 26, 2014 by Claude_Dreyfus

[bgman]

[bgman]

Hi Rabs

Don't know if you're interested, I've attached three photos of my efforts so far showing a proposed 4mm model of Bath Spa.

Having started to recently follow your post and the methods used I'm considering re-making this. Card modelling the main buildings and having the use of a laser cutter for the first time ( for the windows ) and made a casting for the many ! doors I might have to rethink my methods.

I applaude your hi-tech approach and whilst my early career was spent in an architects practice CAD didn't come along for many years later, which I suppose makes me old skool ?

I am enjoying your work very much and find it pleasurable to follow if not frustrating because I would have to learn 3D ( not sure my head would survive the pressure LOL)

 

Kind regards

Grahame

[bgman]

P.S.

I think that controlling the pointwork over the oblique/skew bridge to the west of the station is one for some head scratching as the is little or no room for standard point motors ( unless the barge men in the river duck! ).

[Rabs]

Hi bgman,

Great to have you along!  I got very confused by your first post - I was thinking to myself "but..but, I haven't built that bit yet - where is that model from?".

I'm very interested, please feel free to add as many photos of your work or anything interesting that you've learnt in your research as you like to this thread.

I can't quite work out on your first photo - is that the station building roof folded back or are you modelling the original Brunel over-all roof over the tracks?

I don't see why you would need to remake anything - it looks like a great start. It's a pretty tricky shape to do and I think that you have captured it very nicely.

 

Funny you should mention the skew bridge.  I've not had time to do much modelling since Christmas but as it happens I'm just preparing to assemble that module (see post 1 - it's the left most of the scenic modules):

 

In the second picture you can see the four cutouts for the point servo motors.  These will use the 'rotating wire in tube' method I tested in post 118.  That way there won't be anything visible under the skew bridge except for some 2mm tubes.  There are quire a few pipes slung under the bridge so I'm hoping that these tubes will blend in nicely.

 

Once I've got this module varnished and glued I'll pose the 3d printed bridge sections, that I made right back at the beginning of the project, in place.

 

You can expect more regular updates for the next few weeks at least.

Edited March 11, 2014 by Rabs

[bgman]

Hi bgman,

Great to have you along!  I got very confused by your first post - I was thinking to myself "but..but, I haven't built that bit yet - where is that model from?".

I'm very interested, please feel free to add as many photos of your work or anything interesting that you've learnt in your research as you like to this thread.

I can't quite work out on your first photo - is that the station building roof folded back or are you modelling the original Brunel over-all roof over the tracks?

I don't see why you would need to remake anything - it looks like a great start. It's a pretty tricky shape to do and I think that you have captured it very nicely.

 

Funny you should mention the skew bridge.  I've not had time to do much modelling since Christmas but as it happens I'm just preparing to assemble that module (see post 1 - it's the left most of the scenic modules):

2014-03-10 21.20.54.jpg

2014-03-10 21.20.12.jpg

2014-03-10 21.18.34.jpg

 

In the second picture you can see the four cutouts for the point servo motors.  These will use the 'rotating wire in tube' method I tested in post 118.  That way there won't be anything visible under the skew bridge except for some 2mm tubes.  There are quire a few pipes slung under the bridge so I'm hoping that these tubes will blend in nicely.

 

Once I've got this module varnished and glued I'll pose the 3d printed bridge sections, that I made right back at the beginning of the project, in place.

 

You can expect more regular updates for the next few weeks at least.

Pleased to be along thank you, and thanks for you interest.

Well, I considered it to be a convertible ( roof ) much like a fold back roof ........Joking!.

It is in fact based upon the original Brunelian overall roof as per J.C.Bourne's lithograph and having surveyed the remaining element several years ago I felt it was about time I started the monster.

The realisation of placing various elements ie turnout motors sank in whilst construction was under way ( pre planning eh!) however, I remain undetered and will carry on at my leisure until it is completed.

My source of laser cutting locally has sadly taken a back step and I am contemplating the purchase of a small one for home use.

The software was "given" to me ah hem! and I used 2D something or other to produce my files for the laser cutting, to which end I'm attaching some further photographs.

Kind regards

Grahame

p.s. I reiterate May earlier comment......... Excellent work, take your time and you will have something to be proud of.

[Rabs]

 I know that the original skew bridge that you are modelling was replaced in the late c.19th (1887?) - at about the same time as the mixed gauge track was removed.  Are you modelling the mixed or broad-only period?  It should be a lovely model when you're done.

Are your laser cut structures card, plastic or wood (or a mix)?

[bgman]

I know that the original skew bridge that you are modelling was replaced in the late c.19th (1887?) - at about the same time as the mixed gauge track was removed.  Are you modelling the mixed or broad-only period?  It should be a lovely model when you're done.

Are your laser cut structures card, plastic or wood (or a mix)?

Mixed or broad ? That's a loaded question !

I have made some trial "test track" for mixed gauge in P4 with varying success, and to do mixed would then turn into a labour of love.

 

As a member of the Broad Gauge Society I do have access to quite a few records for trackwork, and with the Barlow rail available it makes for a more authentic track.

 

I have mused long and hard over this question and feel that it will most likely be broad gauge ultimately.

That said I am about to embark upon a finescale 00 model ( slightly reduced in length) of Box station in the Edwardian period, just so I can "play trains" because in my view it's what I have built my stock up for.

 

The structures are card and doors cast from my own moulds with the main body of the building hand cut using the good old swann- Morton blades.

 

Whilst the bridge structure and components were cut on the laser using card as an exercise I'm tempted to now use something more robust so watch this space.

 

Rember, a layout is for life, not just Christmas !

[Howard]

...I used 2D something or other to produce my files for the laser cutting,

 

That is probably Techsoft's 2DDesign, which I use for my laser cutting projects. I have found it an excellent product and very intuitive to use - far better than the majority of software I've used over the years.

 

If you do buy your own laser cutting machine, make sure it can handle 2DDesign files - not all of them can.

 

Howard.

[bgman]

That is probably Techsoft's 2DDesign, which I use for my laser cutting projects. I have found it an excellent product and very intuitive to use - far better than the majority of software I've used over the years.

 

If you do buy your own laser cutting machine, make sure it can handle 2DDesign files - not all of them can.

 

Howard.

Thank you Howard,

I've had a look at this software and it seems to be the right one for the job, and I would seriously consider it for use with a laser ( assuming I bite the bullet and buy one!! )

Other options being a Silhouette cutter or having followed Paul Brambrick's blog on the Bristol Train Shed diorama 3D is always an option, so many choices, so little time.

 

Grahame 

[RFT]

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.

 

On working slip coaches - My Grandfather had a working slip coach mechanism on the large 3mm layout in his loft that he built during the 70s, and that I loved playing with growing up during the 80s.

 

the mechanism, as I remember it, was as follows.

 

with the line clear, and the right isolated sections set, you had to press a push button to activate the system, then set the express off with the controller on the right speed setting.

 

There was a magnet in chassis of the slip coach, which activated a reed switch under the track. this reed switch released a weight to roll down a sloped channel, towards another switch. (this was just a timer - these days you'd use a 555 chip circuit or similar).

 

this switch fired a solenoid that raised (and then lowered) an uncoupling ramp, that uncoupled the slip coach - I think the standard tri-ang couplers were just filed to remove the locking hook.

 

The coach then just rolled into the station.

 

My Brother's still got the wiring diagram for the whole layout.

 

The problem would be, from a model point of view, that the model rolling stock would need to freewheel into the station (instead of being braked), and therefore the uncoupling point would need to be defined by that. though I suppose one could try and increase friction on the slipcoach's axles if it were overshooting.

[Black Napkin]

 

I would have to learn 3D ( not sure my head would survive the pressure LOL

 

Kind regards

Grahame

Fortunately for you you would only need to learn how to 3D model structure (texturing and lighting are unnecessary for 3d printing)

My best suggestion to you here is check out what tutorials are free online there are a multitude of modeling tutorials on YouTube, needless to say they will relate to a certain 3D software package eg: Cinema 4D (this is the one I use simply because it has a reputation for being very 'user friendly)

See the attachment.. this is a custom built layout that I made to suit my workflow

Do a YouTube search for Shepperd O'neil ...he has an awesome channel with many well presented and easy to follow tutorials,

 

if you are completely new to digital 3D there are many 'basic' tutorials out there to get you going and forums where you'll find people only too willing to help.

 

 

good luck with what you do

Cheers Rich.

...the first step of a thousand is the hardest

Edited March 15, 2014 by Black Napkin

[bgman]

Fortunately for you you would only need to learn how to 3D model structure (texturing and lighting are unnecessary for 3d printing)

My best suggestion to you here is check out what tutorials are free online there are a multitude of modeling tutorials on YouTube, needless to say they will relate to a certain 3D software package eg: Cinema 4D (this is the one I use simply because it has a reputation for being very 'user friendly)

See the attachment.. this is a custom built layout that I made to suit my workflow

Do a YouTube search for Shepperd O'neil ...he has an awesome channel with many well presented and easy to follow tutorials,

if you are completely new to digital 3D there are many 'basic' tutorials out there to get you going and forums where you'll find people only too willing to help.

good luck with what you do

Cheers Rich.

...the first step of a thousand is the hardest

Hi Rich

 

Thank you for your input on the subject, I'm very much obliged to you.

I'm extremely impressed with the work carried out on the Bristol Temple Meads diorama , which only serves to push me further with learning the software which is now at our disposal, with a view to producing items / scenes etc for my proposals.

My background is in architecture / building, having recently take early retirement from Building Control ( I was the nice one ! Apparently ?). I suppose you could put me in the " old skool" Rotrings/ pencils etc. but if there is an easier way to achieve the goal I'm happy to embrace it.

I spent part of last week in Bath taking photographs of the Sydney Gardens area and some more measurements of Bath Spa station, which seems to have changed somewhat since the last time I was there surveying the buildings.

 

Once again, thank you for your help on this subject which may be put on the back burner for a short while whilst I get further info and learn new techniques.

In the meantime I've just finished erecting some baseboards for a proposed GWR themed layout ( oh! no not another one) around the Edwardian era, and it'll give a chance to " play trains" after many years.

 

Kind regards

 

Grahame

[Rabs]

Almost finished gluing up the three new modules now.  Here is the skew bridge module with the 3d printed bridge tacked in place.  The pier doesn't quite fit below the bridge at the moment, so that will need adjusting.

 

Next step with this module is to add the point motors and the wagon shunting apparatus (see post 108) and check all of that before laying track.

[bgman]

Almost finished gluing up the three new modules now.  Here is the skew bridge module with the 3d printed bridge tacked in place.  The pier doesn't quite fit below the bridge at the moment, so that will need adjusting.

2014-03-16 22.40.00.jpg

 

Next step with this module is to add the point motors and the wagon shunting apparatus (see post 108) and check all of that before laying track.

Hi Rich,

Don't worry about adjusting the central pier, it'll all get sorted out when the river rises !!!!

Joking apart it's looking the business as they say, I trust you are pleased with it so far.........the answer by the way should be YES !

because it is impressive.

Good luck with the turnout motors !

Grahame

[Rods_of_Revolution]

The bridge is looking great! I spent my college years in Bath and still go there often, to photograph the trains as well as enjoy the pubs and The Little Theatre Cinema. I know the city well and I think this layout will really do the city justice, I'm enjoying seeing your progress!

 

Cheers,

 

Jack

[Rabs]

I'm not dead but sadly I have had almost no time to work on Bath since March.  This afternoon, however, I had a chance to have a little play with something that I've been thinking about for a while.  A few months ago I came across this:

And I thought that the same idea could be applied for moving road vehicles in scales too small for on-board motors.  It would also be significantly cheaper than things like the Faller car system.

On doing some digging I came across this:

http://spritesmods.com/?art=magnmicrobots (the next button is fairly inconspicuous at the bottom, but it gets interesting about 3 pages in)

So how hard can it be?

 

I tried a similar basic test, but with a diamagnetic carbon layer over the PCB.  Simple 1D motion with a 2mm vehicle works quite well:

I'm going to design a PCB made which can do 2D motion and drive the vehicle around corners.  Also, with electronic control of switching between traces I will be able to make the motion nice and smooth by using something similar to stepper motor microstepping.

Edited September 5, 2014 by Rabs

[Rabs]

Yesterday I tested the first electrical and track connections between boards.

 

 

Electrically everything works well and there is no wobble as the loco crosses the join.  One bit in the middle of the right hand board that needs smoothing out but that's not an issue for now.

 

Now that's all checked it's time to get on with tracklaying on all the other modules!

Edited September 6, 2014 by Rabs

[artizen]

The little truck is COOOOOOOOOOOOOOOOOOL!!!!!

[raymw]

Hi Rabs

 

 

I tried a similar basic test, but with a diamagnetic carbon layer over the PCB.

Where did you acquire that, as a sheet material?

If you can sort out the microstepping, then the track spacing can be coarser, saving on the cost of mosfets, etc.  I've a feeling you will need to make the front wheels steerable, with the magnet attached to them, else there will be a tendency to drag the vehicle sideways at corners. I was thinking that further savings could be made if the coils were connected //, but in separate batches, so to speak. That would prevent individual control of each vehicle, but that may not matter.

Best wishes,

Ray

[Rabs]

I've been experimenting with a variety of different materials. Bismuth (highly diamagnetic) is available in pellet form on ebay quite cheap but I've not been able to form into a flat sheet because I can't find a flux that will work with it.  Plain graphite sheet is cheap and available from RS but only very weakly diamagnetic (that's what this video shows). I suspect that most of the benefit is from reduced friction rather than any significant diamagnetic levitation. Finally Panasonic do a pyrolytic carbon sheet branded as PGS sheet, available from most electronics distributors like RS and Farnell.  I've ordered some to try with but it's not arrived yet.  It's quite expensive (£15 for a 10cmx10cm sheet) but it should be strongly diamagnetic and roads in N are only small.

In fact I don't think that the diamagnetic layer is really necessary, but it does help to reduce the current needed.

 

I think that the ideal spacing for the traces will be approximately the same as the diameter of the magnets used.

 

You're absolutely right about connecting the coils in banks so that each line doesn't need to be independently switched - I plan to do something along these lines.

 

I was planning to do turning by having two magnets of opposite polarity at either end of the vehicle, so that they can be separately controlled. The wheels on that lorry don't rotate, in fact they aren't even touching the surface but are riding a fraction of a mm above.

[raymw]

Hi Rabs,

 

Bismuth is used in shot gun cartridges and fishing weights (due to restrictions on lead). It has a pretty low melting point. I expect the ebay pellets are alloyed (often tin) but it may not effect the diamagnetic effect. It may be possible to cast the metal in a thin sheet. If the diamagnetic property is so important, then I think bismuth would be the way to go. I'm thinking it could be electro plated onto a carrier. Not sure how thick it would need to be, and if the carrier was a brass sheet, if that would hinder the effect. If Bismuth resisted chemicals that etched brass, then easy to remove the brass. Looking at this table http://hyperphysics.phy-astr.gsu.edu/hbase/tables/magprop.html#c1 I'd guess the brass backing sheet would not be a problem. Since water is diamagnetic, than maybe a canal instead of a road? 

 

Best wishes,

 

Ray

[Rabs]

Bismuth is used in shot gun cartridges and fishing weights (due to restrictions on lead). It has a pretty low melting point. 

Thanks for sharing this. I actually spent some time experimenting with diamagnetic materials at the nanoscience centre in Cambridge a few years ago so I'm familiar with it.

 

 

 If the diamagnetic property is so important, then I think bismuth would be the way to go

 

I'm afraid that I have to disagree on this one.  Bismuth has a lower diamagnetic coefficient than pyrolytic carbon, it's harder to form into a sheet and it has significantly more friction on most plastics and metals.  The ideal thickness is ~0.8mm, which is too thin to cast in a mould because the surface tension of molten bismuth means that a minimum wetting thickness is about 3mm.  Rolling a sheet would be possible but I don't have the tools to do this at home. Alternatively, if I can find a suitable flux then I could cause it to wet onto a sheet of another metal.  I may come back to look at this if it proves necessary but for now I'm going to see how far I can get with carbon.

Thanks for the help!

Edited September 7, 2014 by Rabs

[Rabs]

It's finally coming together:

 

All but two boards assembled and ready.

 

I like this shot - I can finally start to get an idea of what the view down the line is going to be like.

 

The last couple of boards are cut and ready to glue together.  Then I'll have to find somewhere with enough space to set it all up because it won't fit in the workshop!

Edited September 9, 2014 by Rabs