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Re: Sarum Bridge

Postby Ozrail » Thu Feb 20, 2014 11:02 pm

martink wrote:Are there any known longevity issues with the wheel bearings, given the fragility of the 3D plastic?

This one I'm still not sure of the answer, as I really haven't come to this issue yet.
Yes I do run my wagons, but not like everyday, and mine have been around a few years now. (Around 3 years+ now)

I do have a Flying Scotsman and a Thomas who runs more often (mainly Thomas) and they have the same setup as the trucks.
So yeah, you should hopefully get a fair amount of running with them.
Check out my Shapeways store for T-gauge stuff.
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http://www.shapeways.com/shops/everythingtgauge?s=0
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Re: Sarum Bridge

Postby martink » Sat Feb 22, 2014 4:03 pm

I've now painted my small collection of diseasels, 3D printed body shells from the usual suspects. All are done in BR blue to match the HST set. As usual with objects of this size, the photo is very, very cruel - they look a lot better at a normal viewing distance. I currently only have a chassis for the class 42 - the others will get their wheels during the next stage of layout construction a few months from now. I also need to see about getting some BR double arrow decals - I don't want to even think about trying to hand-paint those! Has anyone been down that road already?

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Re: Sarum Bridge

Postby jesse6669 » Sun Feb 23, 2014 12:04 am

Looking really, really good!
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Re: Sarum Bridge

Postby martink » Mon Mar 10, 2014 7:19 am

I hadn't intended to do any more work on the layout for a few months, but it was calling to me... looking at me reproachfully every time I walked past... :( So, here goes another week or two of effort.

Progress so far:
- scenery: basic substructure done with removable hilltops to allow access to the balloon loops, backscene cutouts for more access, started work on the stone facings for the viaduct, ordered a castle for the larger hill (Lilliput Lane's Conwy Castle just happens to be about 1:450, plus it looks more interesting than Old Sarum).
- rolling stock: added BR double-arrow decals to the locos (the smallest N gauge size is only a little over-scale), more chassis and 3d-printed stuff on order (enough to give me three runnable trains, even if a little short and under-powered)
- electronics: built and tested the three PWM controllers (the overload protection circuitry ended up as complex as the basic controllers!), automation computer design under way to fit on the same circuit board, basic panel design and location finalised.

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Re: Sarum Bridge

Postby hedge » Mon Mar 10, 2014 7:56 pm

The BR arrows look great as does the controller PCB. So glad you decided to progress the layout!
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Re: Sarum Bridge

Postby martink » Tue Mar 18, 2014 3:25 am

I've been making slow and steady progress on the layout. There are about half a dozen separate sub-projects underway, most of which should come to fruition in a week or so (with pictures), but just a quick update for now...

Scenery - I've pretty much figured out a rough plan for what goes where, depending on how various structures & such work out as the various bits and pieces arrive at my door.
Rolling stock - I've motorized the class 55, added a short newspaper train and have a pile of new stock ready for painting. Longer term, I will definitely be going with two permanently-coupled & wired motor units per train.
Electronics - the automation is up and running in full speed / sudden stop mode, and I am currently working through some problems with the speed control relays. Sigh. The first-attempt signals are behaving themselves and proving very useful during development, reprogrammed as needed to display the state of the track sensors, the speed relay settings, etc.

As hoped for, one of the end-hills gets a slightly-underscale castle along with the requisite tourists and car park... Some resurfacing and painting will be required to blend it in, but the Lilliput Lane product is a very, very nice model. It actually looks better in reality than in the pictures - lots of interior detail, which you can see because there is no roof!

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Re: Sarum Bridge

Postby martink » Sat Mar 22, 2014 4:33 pm

A few more sub-projects completed and closed out:
- the current round of rolling stock expansion is basically done - lots of wagons painted up ready for wheels, couplers and more motive power.
- the automation is up and running, and the signals are fully functional though still only the initial trial version (bent pieces of optic fibre) for now.

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Re: Sarum Bridge

Postby tjejojyj » Tue Mar 25, 2014 11:42 am

Hi Martlink,

I don't know about anyone else but I'm impressed. Can I ask what you are using for the automation? Some programmable chip?

I have a Pololu Baby Orangutan microprocessor board (http://www.pololu.com/product/1220/) and I'm going to have a stab at using this as the basis of my PWM controller. (I bought it last year out of curiosity to learn about them but hadn't done anything with it). It seems to me that this could also be used for automating features on basic layout.

Regards,
Tim J.
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Re: Sarum Bridge

Postby martink » Tue Mar 25, 2014 3:53 pm

I standardized on the PIC16F690 some time ago as a good general purpose device, and it is pretty much equivalent to the one on the CPU board you are using except that it only has one set of PWM outputs instead of the two available to you.

Dead easy to use - just connect 5V and ground, then do what I want with the 18 I/O pins. In this case, I have hooked up 8 LDRs as track sensors, a MAX7219 to drive 64 LEDs for signals and a future illuminated signal box diagram for the spectators, a couple of switches and LEDs on a small control panel, and a 74LS164 shift register to give me a few more outputs for driving the speed-control relays. There was enough room on a single piece of Veroboard for all that plus 8 relays plus 3 PWM controllers. The software is written using the free version of the Hitech C compiler. If you are interested, I'll be putting the circuit diagram, circuit description and code up on my website sometime in the next few days.

Basically, all of those mid-range chips are very similar, whether PIC, ARM or whatever. Unless you are doing something unusual or trying to squeeze every last cent out of a commercial design, it is generally a case of going with what are you comfortable with, what software you have available, etc.

So, what sort of automated features are you thinking about? Some are much easier to implement than others, and not always the obvious ones.
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Re: Sarum Bridge

Postby tjejojyj » Wed Mar 26, 2014 1:57 am

martink wrote: So, what sort of automated features are you thinking about? Some are much easier to implement than others, and not always the obvious ones.


I was initially thinking of having two trains running in opposite directions passing in the stations but the reported unreliability of the points means I will just aim for two trains chasing around a continuous loop stopping at each of the stations. Rather than switching blocks between fixed speed controllers as you have I was thinking of switching the blocks between two controllers that each follows each a train and automatically adjusts the speed. (It would be nice to program some inertial acceleration and braking but I'm under no illusions that t-gauge is not likely to be up to such refinements.)

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