Tuesday, 28 July 2015

So that I can finish the track, I need to lay some scenery down

One of the features of the track layout is the sunken coal drops along the front. I have a Walthers Cornerstone National Fuel Depot kit.

As you can see, this comes with a berm leading up to some coal drops. I did plan to use this on my previous layout as I wasn't in a position to cut down into that. I was going to use it on this layout but a comment on the blog suggested that dropping the ground level would make it more interesting.

The good thing about foam board is that you can just cut away. So long as there is some adequate bracing in then everything stays nice and strong. So I cut away. This is where I got to.

I have cut away the base, built the trestle and the fuel tanks and got everything into place. I then gave all of the groundwork a covering of Sculptamold. Later this evening, I gave the fuel tanks a coat of Vallejo Aluminium, the wet and dry paper laid as a road a coat of german field grey and then used one of my airbrushes to spray a coat of brown all over the area.

Obviously, the wooden trestle and the fuel tanks won't stay like this and I haven't even started on the distribution building.I have lots of weathering pastels and washes to make it look as though it has been handling coal for years! The fuel depot will be used as a refuelling point for the SW7 as well.

Monday, 27 July 2015

Fitting Cobalt Point Motors - that was fun!

It took a lot of effort and time to get the point motors working. I completely misunderstood the way that these motors work. I got the switching working first time but getting the frog polarity sorted took a good deal of time. It all seemed very simple. I had the main power bus laid by the two stripes of copper tape laid earlier. As I had used red and black wires for the track power, I decided to use orange and blue to connect up the power to the motors.

I had made a template to help lay the points to get the  slot for the  motor fulcrum bar and for the hole to accept the wire for the frog polarity in the right places. I also made a template to fit each motor to the underside of the baseboard. Each motor was fitted using the supplied double sided pad. I did install the four mounting screws as well and they held quite well in the foam board. I was concerned that the motors may skew under whatever force was applied but, in fact, there was no pressure on the motor at all once firmly in place. The fulcrum bars were trimmed down to below rail level using a cut off disc in my Dremel. Lastly, I carefully ensured that the orange and blue wires were all installed with the same polarity.

It is very simple to configure up the motors with the correct DCC IDs. On each motor there is a small switch. Set it to the program position. Using the handset, you then send an accessory command to the chosen address. DCC Concepts recommend that you do this twice but I found that once works. Set the switch back to the run position and it is all done. I quickly set my points up using just 1 to 7 across the two boards.

I put the two baseboards together, connected the two using 9 way D Sub Connectors. It was then that I got a short across the tracks. It turned out that I had crossed the connection of one connector to its bus. How I put red to black and black to red defeats me! After sorting this out, I connected the NCE Power Cab to the bus. As I hadn't yet received my new Broadway SW7, I used my B&M RS3 as a test loco.

On connecting the NCE unit, all of the point motors carried out their self centering operation. On testing each one, they all operated as expected. I did have to adjust the slider on the fulcrum bar of a couple of the motors to ensure that the points actually closed with sufficient force to keep them in place. I then tried to run the loco and immediately got a short as it met the first frog. Two days of frustration followed. I put a posting up on RMWeb (one of the UK's big model railway forums) and got lots of ideas but nothing helped.

I built a test bed to have a clear idea what was going on but that worked correctly, so I was totally bemused. I then tried the loco through each point and found that it would go through some of them but not others. After a lot of head scratching and loss of sleep, I finally realised what was going on. When testing with a continuity tester, I found the following situation on the good points.
where the red line shows no short and the green indicates a short. This is what you expect and means that the frog is powered with the correct polarity. However, on some of the points, I found the following situation:
On these points, the frog was set to the wrong polarity. I had a bit of an epiphany when I saw that, from one perspective, all of the good points were in a facing position and all of the bad ones were trailing. Slowly, I realised that I had been thinking that the Cobalts were like the old Frog Juicers that I was using previously but they are not! The Frog Juicers start up in a random situation - so the polarity of the frog is indeterminate. This doesn't matter because, when the loco hits the point, the Juicer sorts out the polarity and puts it right if need be. The Cobalts, on the other hand, are switches that conform to the way that the logic says they should be. So, if a right hand point is set to the straight road on start up, the frog will be set the same way. This is based on the polarity of the power coming in, in the sense of which side of the bus is set to which connection. My realisation told me that a trailing point would see the polarity as opposite to a facing point and, thus, would power the frog with the opposite polarity. hence my shorts! This was quickly tested by switching the orange and blue wires on the trailing points to the opposite way to the facing and everything worked. It was pointed out, when I reported this on RMWeb, that this would also need to be done if the motor was fitted in the opposite way on a point - say because of a baseboard element being in the way. I have to say that I would have thought that this might have been indicated in the documentation but I can find no mention of the issue.

Friday, 17 July 2015

S & NE - the track is down and the wiring is done.

I have put together the two main boards. As mentioned, these are made of 5mm foam board and are extremely light. Each board weighs just 750 grams (1lb 12oz) but they are very well braced and have self levellers to get them straight and level on the worktop where I am going to run them.

There is one more track to lay. That is going out along the front towards the right end. This will be the track that goes out over the coal drops but I thought I would leave that complication until I had everything else done.

Here you can see the underneath in all of its glory. You can see the main DCC bus running along the length of the two boards. The electric feeds are carried from one board to the other by a 9 way D-Sub connecter (of old VGA fame). This has enough connectors for me to run the frog feeds from one board to the other to provide an LED display of switch settings. The little bumps on the bus are where I have cut through the copper because there is a switch at that point and I need to cut a hole for the point motor wire!

The above in an annotated close up image of a section of the board showing all the salient features.  The little blobs of hot glue that you can see are where I have fixed the track pins into place. I lay the track on double sided tape but it needs some extra help so I put track pins through and then hot glue to hold them down. Once the track as been ballasted, all of the pins with their attendant hot glue tips can be removed.

My last couple of images show how the two boards are held together. remember that these two boards weigh only 1.5kg in total so are not subject to much kinetic energy if moved so the joins can be held in place quite easily by creating two foam core locks. The first image shows it all in place and the second shows on lock in the halfway out position. (The two boards were not fully in place hence the gap under the rails.)

This might look insubstantial but it works very well.In fact, when I have built some scenery and placed some structures, I can use these self same slots to insert spacers between the two boards for storage (for more please wait until later).

I have checked all of the electrics and, as you can see in the first image, run my B&M RS3 up and down. It had some trouble with shorting frogs but I haven't got to sorting them out yet - this will be managed by the point motors. This weekend I am making my first visit to the Thamesside Modellers which is a North American Model Railroad club some 23 miles from me. I will let you know how I get on. I am expecting to start installing the Cobalt IP point motors on Sunday so more then.

Thursday, 9 July 2015

Testing my new Cobalt point motors

The Cobalt switch motors are very flexible. They can operate on DC or DCC, change the polarity of the frog, power LEDs to show the road selected and interface with switches or other devices. I only need  the basic switch operation, the frog switching and the LED management.

As I have never used them before, I thought I would put up a test rig. Here it is with the switch in place. I knocked it together from some scrap foam board so that it was installed in the same environment as the final layout.

The track is held down on double sided carpet tape and alignment is fixed by the use of a few small pins through the ties. On the real layout, everything will be firmed up when the ballast is laid.

OK, so we switch to the underneath now.

This is the Cobalt motor in place. It is held there using the same double sided tape as for the track. In the final installation, of course, I will be using the DCC Concepts supplied double sided pad which is a lot stickier.As you can see, there are two wires (red and black) going to the track. These provide the power for the motor.There is also a resistor installed in the frog polarity control. This is connected to two LED (one reversed vis-a-vis the other) and one leg of each LED is connected to the track feed.

I have set the accessory number for the switch. This is easily done. You just move the little on-board switch to the Set position and use your DCC controller to address the switch - I used Accessory 1 for this test. It gets the command and sets the address. From then, you put the switch back to Run and you are done. I now have a test switch that is operated by my NCE controller and gives me a LED indication of which road is set.

You might notice that both LEDs are white - I don't have any other colours so I have some red and green ones coming. This is going to be fun!

The baseboard is finished - ready for the next step

I have finished making the baseboards. Today, I fitted some adjustable bolts to the corners of each board. I then set the boards up on my work top in the hobby room and got everything at a matching level. Here you can see it in place.

Here is a close up shot of the levelling system. There is one of these on all eight corners.

The next step is to test out my new point motors. I have just purchased 7 of the nice DCC Concepts Cobalt IP Slow Action Digital Point Motors. These are nice units that have a decoder built in. Not only that, but they have a connection to manage the frog polarity plus two extra connections for LED outputs ti show point orientation. Very clever - and all for the price of a Tortoise. I am going to build a small test bed with a single point and two spurs to test out the wiring but also to test out the point motor fitting. As I am using foam board, I have to make good arrangements for the mounting otherwise the motor could, over time, break away. More on that tomorrow.