In our discussions on Monday 20 March, we briefly considered whether a corner section would be worth considering to enable modules to be linked without going on forever in a straight line.
The obvious way to do it would be a square board the same front to back dimension as the module boards. The SMS BB021 boards are 555mm wide and 225mm front to back, with 4mm of that taken up by the thickness of the backscene. https://www.scalemodelscenery.co.uk/bb021-micro-layout-baseboard-in-a-box---centre-extension-for-bb017--bb020-9123-p.asp (https://www.scalemodelscenery.co.uk/bb021-micro-layout-baseboard-in-a-box---centre-extension-for-bb017--bb020-9123-p.asp) A 225x225mm board would fill in a 90 degree turn between two boards, but would imply a very tight radius on the track. I've done the sums in the next para.
Brian Elder suggested 45mm from the front of the baseboard to the foot of the frontmost rail. The foot of Peco code 80 rail is 1.39mm wide and the head 0.63mm, so doing the sums, the centreline of the track ends up 50.51mm from the front edge of the board. The board is 225mm front to back (including thickness of backscene) so the track centreline is 174.49mm from the back edge of the board.
174.49mm would be the radius of the track to make the 90 degree turn and doesn't include any allowance for a straight bit at the board joins. That's 6.86 inches. If we allow 20mm straight sections at the board joins, the radius goes down to 154.49mm or 6.08 inches!
For larger radii, we would need either to construct our own corner board or have one custom laser cut to fit. In the attached image, I've dimensioned out a corner board to give 225mm radius (1st radius or nominal 9 inch) with 25mm straight sections at each board join. Larger radius versions would look much the same but have a larger footprint.
This is definitely not something to be considered unless the ScOONs modular project takes off to the point that we have length issues!
Ian
I've just realised that I'm probably over-thinking this corner thing. A perfectly reasonable solution would be to glue two of the ordinary module boards together at 90 degrees and to cut away the unwanted section of backscene to produce an L-shaped board. It's still small enough not to be too unwieldy.
The attached picture shows such an arrangement with a 12 inch radius curve on it (same radius as Peco medium radius points).
Ian
That seems like a useful solution. It keeps the materials consistent and turns the situation into one of someone producing a bespoke pair of modules that do not have to follow the requirement for track entry and exit points to be at the usual place and angle at the internal join.
Making boards in pairs may appeal to some and at a later stage as it means they can be transported 'top to tail', held together by end cheeks that will also protect the rail aligners.
What is the maximum sort of radius that will fit the configuration?
Another thought - a double module is a good opportunity for a passing loop of decent length. A rail join on a curve is trickier than one square to the edge and two doubly so, but it might be achievable.
If we get enough modules to extend round a corner then being able to send trains from opposite ends simultaneously might be good.
Hi Guys
Looks like an ideal area for a turntable
Thanks
Alan
Graeme
I am not one involved with the proposed layout(s) but nevertheless would like to stick my head above the parapet and suggest metal paternmakers dowels for board alignment. Many years of experience in exhibiting and learning the hard way are behind that suggestion.
Malcolm
Quote from: Malcolm on March 29, 2023, 10:49
Graeme
I am not one involved with the proposed layout(s) but nevertheless would like to stick my head above the parapet and suggest metal paternmakers dowels for board alignment. Many years of experience in exhibiting and learning the hard way are behind that suggestion.
Malcolm
Thanks Malcolm. Yes, that's what I've used in the past too. A convenient way to achieve alignment is to join boards, lay the track across the join and cut it in situ.
The issue we have and are trying to resolve is that of keeping the track aligned as well as the baseboards when modules are built by different people at different locations and the first time they come together may be at an exhibition. Some sort of jig or 'standard' that can be shared appears to be essential and that's what we are looking at at the moment.
Also a modules are very small and there may come a point where a significant part of the module is taken up by any floating or adjustable sections of track at the joins, so the solution should not be too obtrusive.
We are still looking for ideas!