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Re: The Bridges at Saltash

Postby dkightley » Wed Feb 20, 2019 3:08 pm

Now I'm over what has been a very busy time with my volunteering for the Tramway Museum, I'm now in a situation where I can start looking to get started again on this project.

Firstly an apology to Siegfried and Matt for not responding to their posts last month. I still have quite a bit of work yet to do on the pointwork before I'm able to show the thing actually working. Once I get there, I'll post some photos, etc....even a video. But I'm nowhere near yet!

Now! Where was I?? I've cleared a space on my workroom and have assembled the baseboards. Now I have the task of laying out what bits I have made so I can work out what to make a start on...…...
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Re: The Bridges at Saltash

Postby dkightley » Wed Feb 20, 2019 4:14 pm

WOW!! I hadn't realised how much I've already done!!

The Royal Albert Bridge....the east approach viaduct printed & ready for fixing the lower halves of the piers to the baseboard:
IMG_3615_red.JPG
IMG_3615_red.JPG (84.01 KiB) Viewed 1036 times

The west approach viaduct also printed and similarly ready for mounting the lower parts of the piers. The point on the approach to Saltash station needs finishing off as well:
IMG_3616_red.JPG
IMG_3616_red.JPG (112.87 KiB) Viewed 1036 times

The main spans of the bridge still need to be designed and printed:
IMG_3617_red.JPG
IMG_3617_red.JPG (127.87 KiB) Viewed 1036 times

Scenery......I have started designing and printing some of the buildings on the West side of the bay. Nothing done for the East side yet:
IMG_3618_red.JPG
IMG_3618_red.JPG (93.18 KiB) Viewed 1036 times
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Re: The Bridges at Saltash

Postby dkightley » Wed Feb 20, 2019 4:26 pm

Trackwork...….the Saltash points are still to be finished. More details will be posted later. I've cut out the track bed for the runarounds. Here is the West side feeder:
IMG_3619_red.JPG
IMG_3619_red.JPG (136.88 KiB) Viewed 1037 times

And here is my strangely named flexi-traverser. The RHS feeds the twin track to the West side of the layout, and the LHS feeds the single track to the East side of the layout...and the branch line that runs up the East side of the river:
IMG_3620_red.JPG
IMG_3620_red.JPG (112.66 KiB) Viewed 1037 times

I have designed and printed a set of quick-release supports for the track bed. Here are some of them in situ, together with the branch line track bed:
IMG_3622_red.JPG
IMG_3622_red.JPG (111.71 KiB) Viewed 1037 times

Tamar Bridge......I have all the sections of the roadway and girder work at the initial design and print stage. Further and more detailed design work needed:
IMG_3624_red.JPG
IMG_3624_red.JPG (136.45 KiB) Viewed 1037 times

Here's a partially assembled vehicle drive unit. One sits on each end of the bridge:
IMG_3623_red.JPG
IMG_3623_red.JPG (128.92 KiB) Viewed 1037 times
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Re: The Bridges at Saltash

Postby dkightley » Wed Feb 20, 2019 4:36 pm

Here's the other drive unit:
IMG_3626_red.JPG
IMG_3626_red.JPG (126.91 KiB) Viewed 1037 times

The drive units move a specially designed chain that has magets in half of the links that magnetically move the cars on a PTFE road surface. Here's a photo of some of the chain links:
IMG_3625_red.JPG
IMG_3625_red.JPG (84.89 KiB) Viewed 1037 times

Electronics and automation......I have all of the MERG pcbs assembled and tested. Most of them have already been running live on The Bridge for a year now and have proved totally reliable. I have also had limited success with scripts designed to automatically runs trains. A complete new set of scripts will be needed for this layout.....

Rolling stock......I have been working on fitting DCC decoders into power units and anticipate to have a good selection available from day 1. I'm currently looking at recreating the new Hitachi sets along with a range of DMU and freight trains.

And I think that's where I am at present. I now need to formulate a plan of attack...…..
Doug Kightley
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Re: The Bridges at Saltash

Postby gbtrains » Wed Feb 20, 2019 7:16 pm

HI Dough

Looks like your on a winner on this layout.

hope you have fun building the rest of it and seeing it running well. :D


Regards
Graham
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Re: The Bridges at Saltash

Postby dkightley » Fri Feb 22, 2019 10:35 pm

At last......some tangible proof I've got back to work on the layout.....

First job......finish the flexi-traverser:

As I'm going to be controlling trains by computer, it needs to know where to stop the trains on the traverser. And for that I've designed and printed some photo-detectors. Here's an almost complete set of parts for a triple sensor unit for the traverser lanes. There should be three resistors in the photo...but I didn't notice I'd caught them in the sleeve of my jumper and catapulted them onto the floor!:
IMG_3629_red.JPG
IMG_3629_red.JPG (142.96 KiB) Viewed 1004 times

Resistors found...and here's the top and bottom with components half installed:
IMG_3627_red.JPG
IMG_3627_red.JPG (114.13 KiB) Viewed 1004 times

The bed of the traverser needs a few holes...one in each trackbed for the light to pass through, a couple of squarish holes for wiring, and a couple of holes for the assembly screws. I even designed and printed a drilling jig for the holes...I must have been high on something to come up with that as an idea:
IMG_3632_red.JPG
IMG_3632_red.JPG (169 KiB) Viewed 1004 times

And a few burnt fingers later.....a working set of three sensors. In the background is one of the electronics boxes...a bit out of focus, but you can see a line of red LEDs, left to right, on, off, off, on & on. The last LED is on because the carriage has triggered the sensor:
IMG_3635_red.JPG
IMG_3635_red.JPG (116.62 KiB) Viewed 1004 times
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Re: The Bridges at Saltash

Postby dkightley » Mon Feb 25, 2019 12:15 am

The flexi-traverser is now functionally complete:
IMG_3641_red.JPG
IMG_3641_red.JPG (74.59 KiB) Viewed 978 times

Two track feeds onto traverser at each end, a triple LDR sensor at each end of each traverser track and each track independently powered so a TOTI (train on track indicator) can sense which tracks are occupied with a power unit.

I still have to add locating brackets at each end, finish off smoothing the wood off, easing and lubricating the moving parts, and fine tweaking the track ends so they match perfectly.

This one assembly is probably the key part of the layout. Without it working spot-on, the train automation will not be possible....

Essentially, a train will enter the traverser at a "behind the scenes cruise" speed, and the TOTI sensor will sense it entering the traverser track. The automation will then slow the train down to a "crawl" speed, and when it triggers the LDR sensor at the exit end of the traverser, the train will be halted. With three tracks on the traverser, I can have two trains parked ready to run up and two trains running at any one time; one on the main line and one on the branch line.
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Re: The Bridges at Saltash

Postby dkightley » Mon Feb 25, 2019 4:50 pm

Continuing my theme of novel designs.....here is one of my quick-release post fasteners....firstly assembled and locked in position:
IMG_3642_red.JPG
IMG_3642_red.JPG (90.16 KiB) Viewed 963 times

And now shown separated so you can see the component parts.
IMG_3645_red.JPG
IMG_3645_red.JPG (85.72 KiB) Viewed 963 times

There's a socket both top and bottom, with a loose post that has a bayonet style fitting top and bottom. Drop the post into the bottom socket....drop the traverser over the top socket...and a 45 degree twist of the post locks everything together!

I have similar quick-lock posts holding all the ply track bed sections behind the layout....which should allow flat-packing the layout for transport, and a quick assembly!
Doug Kightley
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Re: The Bridges at Saltash

Postby dkightley » Sun Mar 03, 2019 5:11 pm

I now have all the track bed laid and fitted...with the exception of a short section where Saltash station is...but that will get finished once I have the point moved on a bit.

Here's a shot of the Saltash end of the layout. The track is twinned from Saltash station round to the flexitraverser:
IMG_3652_red.JPG
IMG_3652_red.JPG (130.38 KiB) Viewed 893 times

Here's the Plymouth side. The track is single from the bridge round to the traverser. The branch line that runs under the bridges is also singl track...it runs from the flexitraverser in a south direction ….and then curves round to a dead end underneath the higher track bed:
IMG_3648_red.JPG
IMG_3648_red.JPG (124.07 KiB) Viewed 893 times

And here's a more general view showing the full track layout:
IMG_3649_red.JPG
IMG_3649_red.JPG (132.13 KiB) Viewed 893 times


One of the things I've had to take into account is assembly and disassembly for transport. Within a few minutes, the track bed off the back of the layout can be stripped off into a manageable pile of sections:
IMG_3654_red.JPG
IMG_3654_red.JPG (91.61 KiB) Viewed 893 times
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Re: The Bridges at Saltash

Postby dkightley » Tue Mar 05, 2019 2:30 am

Some serious progress! I've been track laying!!

As I nicked the new track I had for Saltash to replace damaged and warped track sections on The Bridge, I've had to resort to using recycled track for the off-piste areas of Saltash. Here, I have laid a couple of sections:
IMG_3656_red.JPG
IMG_3656_red.JPG (139.53 KiB) Viewed 865 times

Amazing to think that the length of track I've laid here has had a train pass over them well over 7000 times.....and no signs of wear! Not even from track cleaning! A few damaged sleepers, though, from inserting and removing from the Forth Bridge deck sections.

I suppose now I'll need to think about getting some power cabling wired up so I can check the track joints are good! That means borrowing back the DCC boxes from The Bridge.... I may have to think about shelling out and duplicating the control boxes - it'll give me some running spares.
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