The Bridges at Saltash

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martink
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Re: The Bridges at Saltash

Post by martink »

That will be another impressive layout. The straight-and-narrow concept looks a lot more practical than your original nearly-square design.

It really all depends on decent points becoming available. I'm in the same boat, eagerly awaiting those new ones.

zdrada69
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Re: The Bridges at Saltash

Post by zdrada69 »

martink wrote: It really all depends on decent points becoming available. I'm in the same boat, eagerly awaiting those new ones.
Do you have any experiance with new motorized points ? Are they unreliable ?
Pawel

martink
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Re: The Bridges at Saltash

Post by martink »

zdrada69 wrote:Do you have any experiance with new motorized points ? Are they unreliable ?
I have tried out the manual and one-way ones, and they look functionally the same as the new electric ones. The problems are trains derailing and poor electrical pickup on that huge dead frog, and I simply find them not reliable enough to support any sort of automated operation. The mechanism to switch the point is something else entirely, with lots of options for that - those new ones, servos, Cobalts, etc. Points are one of the reasons my plans for a new layout are on hold at the moment.

I had a long chat with Paul Blake while enjoying his model of Orbost at a local show a couple of weeks ago, and we were both lamenting the point problem and what we could do with some good ones!

And as Doug implies, reliable points are very nearly a make-or-break issue for a layout based on the Tamar bridges. A poor second choice would be to make one line a dummy (maintenance work in progress!) and run trains only in one direction. That old exhibition tradeoff between reliability (especially for a one-man show) and realism.

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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

I'm going to make ......or get made for me....a custom shallow angle point for the location at the West end of the bridge. The twin track will then disappear off the layout and run round behind the layout....and merge back on the East side of the bridge as a single line.

Behind the scenes there will be a half-traverser sort of point made from a piece of flexitrack fixed onto a pivoted piece of wood or similar....hopefully motorised, as will the viewable set of points. This way, I can have two trains running in opposite directions....
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

One of the things that has held up my decision to proceed with this project was the one big "challenge" I was likely to set myself......getting moving traffic on the Tamar Bridge.

Over the past few weeks I've been doing a bit of sketching out of designs for what I was hoping to be a successful traffic movement system that would not look out of place in the relatively shallow profile of the road deck. And I think I've proven to myself that is actually is possible to achieve. My objective was to have two separate mechanical link conveyors...one for the slow lanes and one for the fast lanes.....running under the road deck surface, with a run-around system at each end of the bridge "off layout" so that vehicles move across the bridge and disappear through a hole in the layout backboard....and the a few seconds later reappear running in the opposite direction. And I intend the fast lane to run at a slightly higher speed to the slow lane!!!

So far, I've created a prototype chain link and low profile track in which it runs. Each chain link is approx 0.9mm long and is 3D printed in one piece...and once I get the final design, I'll need a couple of hundred or so to form the two chains. I've also designed and printed a short section of an early design for the road deck.....complete with four built-in tracks. I've sourced and obtained some PTFE strip that will act as the road surface. This strip is a nice light grey colour that will be perfect!! And finally, I've purchased a bag of small magnets ....tiny little buggers as well!!..... for burying in both the chain links and the underside of the vehicles.

Well! Its early days....but I seem to have made quite a good start on what are some of the technical bits for the layout. I'm not intending to post many images of progress on the tricky bits until I get a bit further on with the design and build...but I am taking photos as I go, so will reveal all eventually!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

Patnewbie
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Re: The Bridges at Saltash

Post by Patnewbie »

Doug .....that's fascinating to see another special layout beginning to come together I really like way you have altered the view for the layout .... an area I knew well , one thing I find in responses to your posts is how many of us are having to work around the horrible points problem of t gauge , so many needing to find a way to have a working layout without the dreaded points being involved myself included ......always hopeful an alternative arrives eventually for us all ......look forwards to seeing how your work of art evolves in time ......

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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

Decided to give everyone a peek into what strange things are coming off my printer......
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These are all test components...
Doug Kightley
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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

Its been a few days since my last post......but I've been beavering away on the design and construction of parts for the Tamar Bridge.

I'm concentrating on the automation mechanism for the lanes of traffic at present. I have purchased a couple of drive motors that have built in reduction gearboxes and have fitted a 3D printed pinion to one of them. On the basis that I'll not be able to break the bridge down into pieces for transport, I'm looking at an assembly that will be almost five feet long!!!.....just within the maximum size I can get ins the back of my car!!! :o
Doug Kightley
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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

I've been making some slow but steady progress with 3D printing parts for the road bridge....but things are not yet at the point where I want to post progress shots. Perhaps in a couple of weeks time! ;)

I've got a few parts for the drive system printed....including two of the biggest parts I've printed so far..both overnight printing jobs! :o

Today, I obtained a copy of a book all about the Royal Albert bridge....which has a number of really useful detailed photos that will help designing the component parts. I'd been chatting with a fellow volunteer at the Tramway Museum and she mentioned she also helps out in the bookshop at Ecclesbourne Valley Railway and they had just got in a as-new copy of a book on the bridge....so I had to buy it!!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

As promised, I now have a photo to show.

Here's a set of 3d printed parts for the assembly at one end of the Tamar Bridge to handle the four lanes of road traffic:
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Top to bottom, left to right.....back row, a two-part chassis (which was too big to print in one piece), supports for the road surface round the run-around wheels; middle row, the end section of the bridge deck with the ramps that feed the traffic onto the run-around wheels, which are next in the picture. Finally the bottom row, the two motors with attached reduction gearboxes and 3d printed pinions, two dirt cheap speed controllers (which I may have a go at seeing how they run trains!!) and the motor mounting clamps.

I need to get some 3mm diameter rod and some nuts and bolts....and see how they all fit together! Kind of sad really....but its "Seniors' Day" every Wednesday at B&Q, so I'll try getting what I want then...and get my old git's discount! ;)
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

And here's the first dry assembly....which went together very well!:
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I've a lot more printing to do before I get any idea whether this is actually going to work or not!!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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Nutter
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Re: The Bridges at Saltash

Post by Nutter »

Looks interesting.prefer mechanical stuff, in theory easier to fault find than the embeded electronics stuff.
Good luck with the rest of the bits.
Mike
DON'T knock it at least I am trying to do something, with only one good hand.

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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

Away from mechanics of the Tamar Bridge, I'm busy looking at other aspects of the layout....and where I can introduce new things that will add to the challenge...

I've recently joined the Model Engineering Railway Group...or MERG...after I saw a demonstration of DCC at the Soar Valley MRC show that showed that you don't need to spend huge amounts of money to get amazing results.....and this has got me thinking of how I can get the extreme slow running needed...scale speeds under 15mph.... for trains over the Royal Albert Bridge. With the new DCC controller cards from CT Elecktronik....and a couple of the DCC kits from MERG, the cost of using a DCC system to accurately control trains on the layout is not looking as if I need a lottery win to fund!

My current thoughts are to use a spare smart phone I have to connect to software on a laptop via wifi that controls trains fed through a MERG DCC control system....costing approx. £70 plus £30 per DCC chip. And having a computer involved, addition of some clever things is realistically possible.
Doug Kightley
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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

One of the plusses of being fluent in the use of 3D CAD is that before you commit to starting to hack away at materials, you can visualise what you're intending to build....and then change the design before committing to starting things. This helps sort out conflicts and getting things to fit right. Here's my current view of the layout:
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And I'm even looking closely at what things look like behind the scenes:
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Obviously, the behind the scenes view is very much a "work in progress" insofar as the track positioning, etc is concerned....but as I'm intending to incorporate a "flexi-traverser", I do need to know what space I have!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

A bit more progress on the virtual design of the layout general arrangement:
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OctViewB2.JPG
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Notable additions are the lighting structure....and I've taken into account wiring routing this time (as its ended up a bit messy on The Bridge)....and a place for a laptop...which will be the main controller for the automation. I've still got the backdrop and the boxing in at either end of the front to do....which shouldn't take much head scratching. At least I can sort out the flat-pack arrangements for the whole layout before I start buying wood, etc! And I can re-use parts from The Bridge!
Doug Kightley
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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

Its nearly a month since I last updated the build.....and a fair amount of progress has happened.

I've made good progress with the DCC side. I've finalised the track sections....twelve in all, and the locations of the spot train sensors....fifteen of them! This should allow me to know exactly where all trains are....how many I have on the layout! I have bought and built an array of pcbs, six nicely named "Twin Toti" boards, four CBus input boards, one output board, one servo control board...and a handful of the LDR detector circuits. Some are function tested, some not. No decoder boards yet! So I can't really go much further on the electronics.

I now have a tube full of flexitrack sections ( thanks, Alan) so I'm ready for getting some track laying done....but no board yet! I have, however started looking at the points. behind the scenes, I'm having my specially named "flexi-traverser"...a three track double bed traverser where each end is independent of the other end. It works as a point, a mini-fiddle yard, and a link from the main track loop to the branch line. I'll be explaining more about it when I start building it. Out front, there's a single wye point between the single track bridge and Saltash station....and I've started building this beast.

I began with a 3D printed mock-up of the track layout based on the layout scale size print I have:
IMG_3282_red.JPG
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This allowed me tp make the initial plan for the point build. I next created a build jig that I could use to form the curves and start building the trackwork. Here's the current state of the point fitted into the jig:
IMG_3284_red.JPG
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To get to this point, I cut and carefully slid the sleeper moulding off most of the track. With the small section left on, I then fitted the track to form the outer rail. I then stripped the sleeper moulding off a short section of track so I had two pieces of rail to file a taper on to form the vee-section. In the rig, these two pieces have been soldered together ready for further steps in the build. The two sections of sleeper mouldings are destined to be threaded onto the two newly formed point exit rail paths...I'll need to trim bits off where they get close. Here's a second shot of the point in the jig with the sleeper mouldings:
IMG_3286_red.JPG
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The plan is for the point as you see in the jig to be mounted on a ply base, which will hold the pivot points for the moving blades and the servo and micro-switch needed to ensure correct power connections.

PS Anyone confused about the sleeper moulding being clear? Its a piece left over from when I built the Bridge, and Alan supplied me with a number of lengths of track that were from a sample batch with clear sleepers.
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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Nutter
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Re: The Bridges at Saltash

Post by Nutter »

Will be following the point build with interest.
What did you use to solder the vee?
You do also realise that you may have to make point jigs available if everything is sucessfull. :?
Mike
DON'T knock it at least I am trying to do something, with only one good hand.

mattd10
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Re: The Bridges at Saltash

Post by mattd10 »

I've been away from T for a little while and I come back to this?! :shock:

Some truly excellent work here Doug!

But as has been said, you may have to branch out into point jigs in the shop! :lol:

msimister
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Re: The Bridges at Saltash

Post by msimister »

Fabulous work Doug. Commercialising good points could be your next project...
Cheers,
Malcolm

NeilM
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Re: The Bridges at Saltash

Post by NeilM »

Good work Doug, very keen to see where this goes. I have been quiet on T gauge for a while, but seeing a good method for building points that really do work could get my layout plans back on track.
Neil

T gauge items in my Shapeways shop http://www.shapeways.com/shops/t450

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