The Bridges at Saltash

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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
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 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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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
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 »

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:
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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:
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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:
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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.

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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

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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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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

No pressure, then! ;)

Unfortunately, as you may have picked up following my build threads, I do tend to jump from one thread of a build to another.....so results on my point may not be that quick. But seeing as there is a bit of an interest, I'll try to put a little more effort in on the point build in the next few weeks....
Doug Kightley
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dkightley
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Re: The Bridges at Saltash

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Pushing on with yet another different aspect...the flexi-traverser....which I've partly made whilst the idea is still reasonably fresh....

The flexi-traverser is basically an oversized point that consists of three parallel tracks attached to rotational slides at each end that move a single track width in a similar way to a point....here's a couple of photos: First...the full traverser
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You can see inside the basic box are two strips of wood that pivot half way across at the extreme end of the box. At the other end, there is an arc shaped slot in the top of the box....into which fits a sliding panel that is mounted on the wood strip. Here's a close-up of one end:
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The lowere strip inside the box is pivoted at the other end and the panel will be screwed onto it's edge. A servo will then move the panel side to side to move the three parallel tracks so that two of the tracks line up with two tracks at the end. The servos are driven from the CBus control system......at least that's the plan!
Doug Kightley
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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

I've not posted anything directly on this thread as I've been concentrating on the DCC side of things which I've been documenting in another thread
( http://www.talkingtgauge.net/viewtopic.php?f=10&t=525 )....so I thought it was time to bring things up to date here as a sort of pre-Christmas progress report.

DCC & automation.....as per the above thread, I've got the electronics of the layout as far as I can go for the time being. The next step is to finish the installation of the LDR sensors and general connection wiring, which can't be done until I get the layout itself moved on considerably.

Tamar Bridge......I've started moving on with the design and printing of the bridge components and bits for the vehicle drive system. The motor drives and controllers/power supply have been obtained and just need fitting when appropriate.

Royal Albert Bridge....nothing started yet, although I may start looking at some of the basic structural pieces after Christmas.

Layout board....I've purchased timber to make the layout board sections, and have started making up the three main sections. This will be followed up by the side and rear extensions. Once all are done, I can start looking at the track bed for the public and behind-the-scenes sections. PVC sheeting similar to that I used to simulate water on The Bridge is on order and hopefully may be fitted over Christmas. Bit of a contrast in the cost of things....15 lengths of 2x1 £13.50.....3 sheets of PVC sheeting £60.00. :shock:

Scenery.....obviously, nothing started as there's a small issue of there being no layout boards.

Trackwork.....I have the basic form of the flexi-traverser assembled and working. I still need to add the short track ends and finish off the guides for the moving sections. I also have the starting work done for the single shallow wye-point that sits at the west end of the rail bridge...I think I've documented this in a separate thread.

Buildings.....I've started by creating a design and print log for the houses and other buildings on the layout....but as of yet, I've not started any CAD work on any.

As with The Bridge, you can see I have several thing in progress at the same time......something I call "Organised Chaos!". I love it! ;)

I'll try to print some progress photos over the next few days.....
Doug Kightley
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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

A few photos as promised...

Layout board partly made...here's the three main sections with the rear behind-the-scenes section in place, with the flexitraverser in its approx. position:
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A closer view of the flexitraverser:
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And a selection of parts of the Tamar Bridge:
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Doug Kightley
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Nutter
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Re: The Bridges at Saltash

Post by Nutter »

looks horribly clean and tidy to me :roll:
At least you now know how much room you have and can do the test stretch across the boards to make sure you can reach everything safely.
Mike
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dkightley
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Re: The Bridges at Saltash

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Decided to get to a significant point for another of the manufacturing threads before the New Year....the production of 3D printed buildings.

Here's the first of many:
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And its the most notable of the buildings...the Union Inn:
Union_Inn.JPG
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I'll need to finish this building with a transfer to get the required image resolution.....

One down......many more to go!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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Re: The Bridges at Saltash

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Now I've got the basic baseboards in their 99% finished form....all surfaced and break down-able for transport/storage, I thought I'd start the new year with a dry assembly of the parts I've so far produced:
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Not bad for less than six months work.

The greatest progress is on the DCC and control system. The six boxes are in approx. their final positions....there's just a wiring harness and individual wires to each track section and sensor, etc to do. The next chunk of work has been on the Tamar Bridge and the vehicle drive system. This is totally untested and unproven.....so I've got a lot to do. The other parts are the flexi-traverser and a half-built wye point.

I'm going to have to take all this to bits and pack everything away soon........I have The Bridge to sort out for it's next show in less than two weeks!!
Doug Kightley
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dkightley
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Re: The Bridges at Saltash

Post by dkightley »

At last.....a bit of Brunel's bridge:
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Its not in its final form yet, but this is one of 17 sections of the approach viaducts. It seems Brunel hadn't heard of standard sized assemblies; two of the sections are 93 ft long, two are 88ft 6in, two are 78ft, two are 72ft 6in, and the remaining 9 are 63ft 6in long...and one of those is wider at one end to allow for the pointwork! And the differing sizes aren't even steps of equal amounts!!!
Doug Kightley
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Re: The Bridges at Saltash

Post by dkightley »

Back in April 2014, I posted a shot of a couple of viaduct sections for the Forth Bridge sitting on top of a stone pillar (post here: http://www.talkingtgauge.net/viewtopic. ... 3&start=12 )

Here we are, almost four years later and I'm posting an equivalent shot for Brunel's bridge at Saltash.........
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Re: The Bridges at Saltash

Post by dkightley »

I've been able to make some good progress over the past few days......

I now have all of the deck sections and under deck sections for the Tamar bridge all printed ready for the next stage....clean up and assembly of the full deck. The whole bridge will need to be one giant sub-assembly, so this will be the first time I get to see how "giant" it will be!!!!

I've moved on the CAD design of the approach viaducts for the RAB (Royal Albert Bridge). I've put together the individual deck sections....which vary in length...to form two deck sections for each end. The Plymouth side decks are ready to print, as is one of the Cornwall side sections. The other section....the one that joins up to Saltash station....is complicated by the fact that there's a point that sits on the last two sections. More on that below....but here's a picture of an early print of the section, held up with three of the stone supports:
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So I can assemble the bridge onto the layout, I've had to make all bar one of the stone pillars in two slot-together pieces, and I've got all the CAD work done for these. Included in this set is a support for the very end of the Plymouth viaduct....which also will have the plywood track bed fitted onto it. So....a bucket full of pieces to print here!

I mentioned the point. Back in November, I posted an early state of the point on a printed jig. Now I know what the constraints of the volume into which I can build the point and its control linkage & power supply wires, I've re-done the jig so I make sure it'll fit once I get the point working. Here's the revised jig:
IMG_3343_red.JPG
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The two sections of viaduct shown represent the two sections that the channel shape replace. Fortunately, there's a deeper girder section for these two sections...and they taper. This makes it possible to actually get the point working!!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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