Curves

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A good tip from the late David Jenkinson is to arrange for tight curves to be viewed from the inside of the curve wherever possible.
MBQ
Reply to
manatbandq
On Tue, 16 Sep 2008 00:19:09 +0100, "Mike Smith" said in :
That's been part of my technique for making the curves and transitions smooth. Another has been the patent 6' way gauge and curve smoothing system, a block of wood with parallel shallow saw-cuts spaced as for a pair of lines at 6' way, which you can run up and down over the track as you lay it - it settles the curves nicely.
Guy
Reply to
Just zis Guy, you know?
What technique do you use for laying them out? Do you cut out semi-circular pieces of ply or do you draw the curves direct onto the baseboards and lay the track to that (just going trough the same at the moment) "Just zis Guy, you know?"
Reply to
Keith J Patrick
48" Rad or Diam? I thought that I had stacks of space but could not contemplate 48 rad!
Regards
Reply to
Sailor
On Tue, 16 Sep 2008 10:28:12 +0100, "Keith J Patrick" said in :
I use Tracksettas for the track and when I cut curves on the baseboard I use a pencil on a nylon line :-)
Guy
Reply to
Just zis Guy, you know?
I made templates out of boxboard, easement at one end and true curve at the other. Total length about 2-3ft, depending on curve radius. One for each radius is enough - just flip it for right/left hand. You don't need to be overly fussy about smooth edges - the flex track smooths out any irregularities in the template.
I like Mike's curve smoother, and intend to copy it.
HTH
Reply to
Wolf Kirchmeir
It all depends on how you build the layout. An around the wall layout allows for much larger curves than an island or peninsula. Of course the smaller spare rooms won't allow 48" R. :-(
Reply to
Wolf Kirchmeir
On Tue, 16 Sep 2008 08:30:49 -0400, Wolf Kirchmeir said in :
Mine, you mean? I'll stick a pic on my website when I get a minute. It's about 4" long, made of a bit of 4 x 1 PAR. Very simple, a hardpoint saw blade is almost exactly the same width as the rails.
Guy
Reply to
Just zis Guy, you know?
Why not do it properly? The railway civil engineers do not have 'curves' of any radius. All curved track on main lines has 'transition' curves which start at a big radius and decrease progressively to the apex of the curve and then increase again. My layout is laid out like this so my curves (it's a big roundy roundy BTW) start around 80-100 " radius and decrease to about 40". You will be amazed at how much better this looks, and how much better your rolling stock behaves. No train should leave a dead straight and go into a curve of even 60" radius . It will look wrong.
Alistair Wright '5522' Models
Reply to
Alistair Wright
Actually, the civil engineers use a "cubic spiral" as a transition between tangent (straight) track/roadway and the curve. Which is a tad tricky to do in the smaller scales, what with precision on the order of 0.01" required. ;-)
Luckily, there's an easy solution: Flex track cannot begin a curve at a point, and will naturally produce a transition curve (or easement or spiral) when curved. So offset the curve about 1/4" to 1/2" _inside_ the curve at the nominal beginning of the curve. Then lay the flex track to within 12" to 18" of the nominal beginning of curve, and bend it round to match the curve about 12" to 18" beyond that point. It will form a very nice transition curve.
You can use the same method with a thin strip of wood to draw a centre line for a template for laying down the ballast former (cork) strips.
Transition curves reduce the sideways swing of the coach/wagon ends as they enter the curve, and so reduce the odds of buffer lock.
HTH
Reply to
Wolf Kirchmeir
I think the cubic parabola (not a spiral) ( y = K*Xcubed) is a bit beyond most modellers to achieve, and in any case in 4mm at least it is not really essential. Strictly speaking the transition length required is a function of the maximum speed and cant on the final curve in question. Again I doubt 4mm models really need as much cant as you sometimes see on people's layouts. It looks good, but isn't really necessary - our vehicles are way too heavy compared with RL and have overscale flanges (except P4).
I disagree about flex track though. I have seen too many exhibition layouts using it where they did actually get it to look like race tracks. The major advantage, after appearance, is of course as you point out, less chance of bufferlocking especially when propelling. The same rules apply to turnouts BTW. The switch rails are not curved to a fixed radius, they are just like any other transition albeit a very short one.
One method of getting flex track to perform an semi-automatic transition is to remove the webs joining the sleepers progressively as you tighten the curve. ( ie every six sleepers, then every five and so on down to about every three). I do this anyway to get the track down in the right place.
Alistair Wright
Reply to
Alistair Wright
There's loads of info about this sort of thing at:
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Martin knows his onions when it comes to track! Apart from the obvious references to Templot, there's plenty of general info to be gleaned. Mind you, why not use Templot anyway - it's a bit over-kill for set-track, but if you want transition curves etc it's the mutts nuts. It's intended for those making their own track, but can be a very useful tool for ready made track too. Works in all major gauges/scales - you can even make your own up! I believe there are libraries for Peco points etc, don't know about other stuff, but creating a Hornby set of points wouldn't take too long once you've got the hang of it.
Cheers Richard
Reply to
beamendsltd
Alastair -
I'm sure you don't mean that real railways don't have any circular curves at all? What they have are circular curves (i.e. fixed radius) connected by transitions to tangent (i.e. straight) track or to other circular curves (sometimes two different transitions join two reverse curves with no straight in between). Transitions start straight (infinite radius) and end at the same radius as the adjacent circular curve.
.
Reply to
John Nuttall
On Tue, 16 Sep 2008 08:51:25 -0400, Wolf Kirchmeir said in :
More than welcome, I can't believe it's novel. Here are some pictures.
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Guy
Reply to
Just zis Guy, you know?
Well I do and I don't, if you can understand why. Most 4mm curves, even on a big layout, are so tight that you would never get to the end of a sensible transition in the space available. My own outfit, which would have ~5ft radius curves if I laid them out as fixed radii, actually transitions from about 10ft rad down to about 3ft 6in and then it's time to start opening out again to reach the end of the curve at the other side of the layout. RL of course would take the transition to a fixed radius as you note. Even pacifics will go round 3ft 6in if it is momentary and starts increasing again. It greatly improves the appearance of your track if curves start with a transition.
Alistair
Reply to
Alistair Wright

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