Because the weekend has been spent almost entirely in the garden, there has been no time for any work on the railway. So I have been thinking and planning, but not actually doing.
The current thinking topic is electronics and control in the storage sidings. These tracks will go in first and I want to put in the wiring at the same time. Because the storage sidings are less accessible than the top tracks, not to mention invisible in normal operation, I want to be able to (a) switch all the lower level points remotely, and (b) know where my trains are so I can set the correct route for a given train.
(a) is relatively easy, if not necessarily cheap. I can motorise each of the points, and if I use the standard Peco PL-10 point motor I can also attach an accessory switch that is operated by the motor itself. This switch can be used to light LEDs depending on which way the point is set. So when the point is changed, the appropriate LED lights up to confirm that the motor has actually fired. Combine this with a probe-and-stud panel showing the track plan, and you get a handy control centre that shows the available routes. Doing this is probably within my electronics ability, if I think about it for long enough.
(b) is rather harder. In the real world, low-voltage track circuits are used to determine where trains are. This is not easily possible in the confined lengths of a model railway - or at least, not without electronics knowledge I don't have. MERG do all sorts of stuff in this area using comparators, but it's not for the faint-hearted.
So I might use an optoelectronic approach. Maplin sell an inexpensive infrared detector kit consisting of one IR LED and one IR phototransistor, both mounted in "side looking packages". With appropriate circuitry, a lamp can be made to light up if the beam is broken. My idea is to have a bunch of these positioned along each of the storage tracks: LEDs opposite phototransistors, acting like security beams. When a train passes along the track it cuts through the beams and causes indicator lights to illuminate on the control panel. With enough such units along each track, you get a signalman's-eye view of the sidings and can see, to whatever accuracy you like, where the trains are.
The theory is simple, but execution requires a lot of components and a lot of extra wiring. I will see how my ideas develop. But before anything else, I have to complete the trackbed construction. Next weekend includes the promise of some time to work on this.
26 May 2009
18 May 2009
Layout test #2
The purpose of the second layout test is to determine the final alignment of the track beds. No track has been fixed yet but the track is more or less in final position.
The photos below are a selection of views from the test.
Above: views of the station area from the left-hand and right-hand approaches respectively.
Above: a train waiting to depart from platform 3. The alignment of this line presently has a switchback curve (under the loco in the above photo) because the chimney breast turns out to be larger than I allowed for on plan (...doh). It means that the available length for platforms 2 and 3 is a bit shorter than I'd like. I am thinking about ways to move the entire station alignment forward, which would allow more space for the platform structure. However, doing this puts pressure on the curves on F5i which are already as tight as I want them to be. I feel some playing in XTrk coming on...
Above: the station throat on B5u. I have added the new board section at the front of the board, but not fixed it yet.
Above: a view of the entire layout as it stands now.
The photos below are a selection of views from the test.
Above: views of the station area from the left-hand and right-hand approaches respectively.
Above: a train waiting to depart from platform 3. The alignment of this line presently has a switchback curve (under the loco in the above photo) because the chimney breast turns out to be larger than I allowed for on plan (...doh). It means that the available length for platforms 2 and 3 is a bit shorter than I'd like. I am thinking about ways to move the entire station alignment forward, which would allow more space for the platform structure. However, doing this puts pressure on the curves on F5i which are already as tight as I want them to be. I feel some playing in XTrk coming on...
Above: the station throat on B5u. I have added the new board section at the front of the board, but not fixed it yet.
Above: a view of the entire layout as it stands now.
04 May 2009
Second incline revisited
A few tweaks later, and the second incline is a bit better than it was.
I moved the start of the incline back to F1, and adjusted the height of the supports all the way along the trackbed. With a longer incline I have been able to soften the gradient and (so I hope) make it easier for trains to get up the slope.
In the course of making these changes I decided to test the slope with real trains. (Only afterwards did I realise that this was the first time I had run a train in the loft!) The revised slope is fine for locos that are running well: I recently acquired an Airfix class 25 from a friend and this pulls a train up the slope quite happily. But an older Lima class 33 struggles; the lesson is that I need my locos to be running as smoothly as possible.
I moved the start of the incline back to F1, and adjusted the height of the supports all the way along the trackbed. With a longer incline I have been able to soften the gradient and (so I hope) make it easier for trains to get up the slope.
In the course of making these changes I decided to test the slope with real trains. (Only afterwards did I realise that this was the first time I had run a train in the loft!) The revised slope is fine for locos that are running well: I recently acquired an Airfix class 25 from a friend and this pulls a train up the slope quite happily. But an older Lima class 33 struggles; the lesson is that I need my locos to be running as smoothly as possible.
03 May 2009
The second incline
Change of plan again. Rather than work on the outer loop (F2o-F1o) I have instead made progress today with the inner loop from B1l round to F4i.
I decided that I really needed to finish off the lower levels, so I know where I can fix the supports to carry the upper-level baseboards. This issue was stopping me from finalising the station approaches on both B1 and B5. With the lower-level track beds all in place I can now finish off the top tracks. Fingers crossed that everything will link up without overly tight curves on F1o/B1u and F5i/B5u.
The "spur to nowhere" visible at the back of B2 will eventually be the feeder for the cassette loader mentioned in a previous post. I won't do any more work on that for the moment as it would just get in the way of more important things.
The trackbed joins at B1l-F1i and F1i-F2i are interesting because here the track is not running perpendicular to the baseboard breaks. If I had made a straight trackbed join at these points, I would have had to make a diagonal cut across the tracks, which would make the alignment less stable. My solution is as follows:
The trackbed join now runs perpendicular to the track for each line, so there is a sawtooth pattern where the boards slot together. This pattern should help the boards to marry properly when being assembled. I will have to do the same on F4i-F5i as here the track will be starting to swing round to meet up with the station approach on B5u.
The "sharp" bits of the sawteeth overhang the boards they adjoin, resting on the frame of the next board. So there's now a rigid sequence to assembly and disassembly of the layout, and all future overhangs have to be consistent with that. Board F1 will now always be the first board to come out, followed by F2...F5 and then the back boards. In assembly, this sequence is reversed.
I am pleased with all of this work except for one thing: the gradient of the inner loop is much steeper than I wanted. Whereas I had planned for the incline to start on B1l as soon as the lower trackbed emerges from under the upper tracks, it actually doesn't start until halfway across F2i. So there is less distance to gain the required height, and the resulting gradient is only marginally shallower than the "standard" 6% Hornby gradient with which my trains have struggled in the past. I will look at that on my next loft visit; it may be possible to make the incline start sooner and so soften the gradient.
I decided that I really needed to finish off the lower levels, so I know where I can fix the supports to carry the upper-level baseboards. This issue was stopping me from finalising the station approaches on both B1 and B5. With the lower-level track beds all in place I can now finish off the top tracks. Fingers crossed that everything will link up without overly tight curves on F1o/B1u and F5i/B5u.
The "spur to nowhere" visible at the back of B2 will eventually be the feeder for the cassette loader mentioned in a previous post. I won't do any more work on that for the moment as it would just get in the way of more important things.
The trackbed joins at B1l-F1i and F1i-F2i are interesting because here the track is not running perpendicular to the baseboard breaks. If I had made a straight trackbed join at these points, I would have had to make a diagonal cut across the tracks, which would make the alignment less stable. My solution is as follows:
The trackbed join now runs perpendicular to the track for each line, so there is a sawtooth pattern where the boards slot together. This pattern should help the boards to marry properly when being assembled. I will have to do the same on F4i-F5i as here the track will be starting to swing round to meet up with the station approach on B5u.The "sharp" bits of the sawteeth overhang the boards they adjoin, resting on the frame of the next board. So there's now a rigid sequence to assembly and disassembly of the layout, and all future overhangs have to be consistent with that. Board F1 will now always be the first board to come out, followed by F2...F5 and then the back boards. In assembly, this sequence is reversed.
I am pleased with all of this work except for one thing: the gradient of the inner loop is much steeper than I wanted. Whereas I had planned for the incline to start on B1l as soon as the lower trackbed emerges from under the upper tracks, it actually doesn't start until halfway across F2i. So there is less distance to gain the required height, and the resulting gradient is only marginally shallower than the "standard" 6% Hornby gradient with which my trains have struggled in the past. I will look at that on my next loft visit; it may be possible to make the incline start sooner and so soften the gradient.
17 April 2009
No longer waiting for the points
The points I ordered have arrived. The Peco double-slip (of which I now own two) is truly a thing of beauty!
I am very much looking forward to finalising the track layout next time I can get up into the loft.
I am very much looking forward to finalising the track layout next time I can get up into the loft.
15 April 2009
Waiting for the points
I'm very excited about the fact that I've ordered my first batch of streamline points for the model. I just had confirmation from the vendor (Osborns models) that they are on their way. When I have the points I will be able to do the final station layout and so decide exactly where the baseboards are best joined at F1-B1 and F5-B5. Because of the clusters of points in the station approaches I need to join the baseboards where the track sections join, not in the middle of a section... hence needing to know how the track lays out before finalising the boards.
I decided not to buy points for the branch line at the moment. I still don't have a clear idea about where the branch line will go, so it seems premature to order in the track and points.
I decided not to buy points for the branch line at the moment. I still don't have a clear idea about where the branch line will go, so it seems premature to order in the track and points.
08 April 2009
Completing the first incline
The first of the two big inclines on this model is now complete...
The picture shows the finished double-track bed for the feeder tracks, with the final running height at top board level. Most of the bed on boards F3 and F4 will be "above ground" in the final model; the tunnel portal will be somewhere at the right-hand side of F4.
At both ends of the incline I have tried to ensure that there is a smooth transition from gradient to level; the upper transition happens in the middle of F3 (looking at the photo, it seems that it may still need a bit of adjustment). I certainly want to avoid changes of gradient at the edges of the boards at all costs, as here the track will be discontinuous as well.
The feeder track beds are made from 6mm MDF (the remnants of my old table-top layout) braced underneath with battens to increase rigidity. Because the top material is 6mm grade rather than 9mm, I have added an extra 3mm of height to the supports at top board level, to ensure that the surface levels align when the 6mm MDF meets the 9mm plywood further round the loop. As I've gone round I have also been adding extra front-to-back battens to F3 and F4, to provide extra strength and make it easier to attach the track bed supports.
I am pleased with recent progress and am looking forward to completing the loop round to the station approach on B1u. Next comes F2 and a bridge over a river!
The picture shows the finished double-track bed for the feeder tracks, with the final running height at top board level. Most of the bed on boards F3 and F4 will be "above ground" in the final model; the tunnel portal will be somewhere at the right-hand side of F4.
At both ends of the incline I have tried to ensure that there is a smooth transition from gradient to level; the upper transition happens in the middle of F3 (looking at the photo, it seems that it may still need a bit of adjustment). I certainly want to avoid changes of gradient at the edges of the boards at all costs, as here the track will be discontinuous as well.
The feeder track beds are made from 6mm MDF (the remnants of my old table-top layout) braced underneath with battens to increase rigidity. Because the top material is 6mm grade rather than 9mm, I have added an extra 3mm of height to the supports at top board level, to ensure that the surface levels align when the 6mm MDF meets the 9mm plywood further round the loop. As I've gone round I have also been adding extra front-to-back battens to F3 and F4, to provide extra strength and make it easier to attach the track bed supports.
I am pleased with recent progress and am looking forward to completing the loop round to the station approach on B1u. Next comes F2 and a bridge over a river!
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